diff --git a/ext/mbedtls/include/mbedtls/asn1.h b/ext/mbedtls/include/mbedtls/asn1.h
index 082832c..96c1c9a 100644
--- a/ext/mbedtls/include/mbedtls/asn1.h
+++ b/ext/mbedtls/include/mbedtls/asn1.h
@@ -2,7 +2,8 @@
  * \file asn1.h
  *
  * \brief Generic ASN.1 parsing
- *
+ */
+/*
  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
  *  SPDX-License-Identifier: Apache-2.0
  *
@@ -59,7 +60,7 @@
 
 /**
  * \name DER constants
- * These constants comply with DER encoded the ANS1 type tags.
+ * These constants comply with the DER encoded ASN.1 type tags.
  * DER encoding uses hexadecimal representation.
  * An example DER sequence is:\n
  * - 0x02 -- tag indicating INTEGER
@@ -87,6 +88,21 @@
 #define MBEDTLS_ASN1_PRIMITIVE               0x00
 #define MBEDTLS_ASN1_CONSTRUCTED             0x20
 #define MBEDTLS_ASN1_CONTEXT_SPECIFIC        0x80
+
+/*
+ * Bit masks for each of the components of an ASN.1 tag as specified in
+ * ITU X.690 (08/2015), section 8.1 "General rules for encoding",
+ * paragraph 8.1.2.2:
+ *
+ * Bit  8     7   6   5          1
+ *     +-------+-----+------------+
+ *     | Class | P/C | Tag number |
+ *     +-------+-----+------------+
+ */
+#define MBEDTLS_ASN1_TAG_CLASS_MASK          0xC0
+#define MBEDTLS_ASN1_TAG_PC_MASK             0x20
+#define MBEDTLS_ASN1_TAG_VALUE_MASK          0x1F
+
 /* \} name */
 /* \} addtogroup asn1_module */
 
diff --git a/ext/mbedtls/include/mbedtls/bignum.h b/ext/mbedtls/include/mbedtls/bignum.h
index 456a804..40cfab4 100644
--- a/ext/mbedtls/include/mbedtls/bignum.h
+++ b/ext/mbedtls/include/mbedtls/bignum.h
@@ -1,8 +1,9 @@
 /**
  * \file bignum.h
  *
- * \brief  Multi-precision integer library
- *
+ * \brief Multi-precision integer library
+ */
+/*
  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
  *  SPDX-License-Identifier: Apache-2.0
  *
@@ -70,7 +71,7 @@
  * Maximum size of MPIs allowed in bits and bytes for user-MPIs.
  * ( Default: 512 bytes => 4096 bits, Maximum tested: 2048 bytes => 16384 bits )
  *
- * Note: Calculations can results temporarily in larger MPIs. So the number
+ * Note: Calculations can temporarily result in larger MPIs. So the number
  * of limbs required (MBEDTLS_MPI_MAX_LIMBS) is higher.
  */
 #define MBEDTLS_MPI_MAX_SIZE                              1024     /**< Maximum number of bytes for usable MPIs. */
@@ -176,7 +177,7 @@
 /**
  * \brief          MPI structure
  */
-typedef struct
+typedef struct mbedtls_mpi
 {
     int s;              /*!<  integer sign      */
     size_t n;           /*!<  total # of limbs  */
@@ -203,6 +204,8 @@
 /**
  * \brief          Enlarge to the specified number of limbs
  *
+ *                 This function does nothing if the MPI is already large enough.
+ *
  * \param X        MPI to grow
  * \param nblimbs  The target number of limbs
  *
@@ -214,19 +217,23 @@
 /**
  * \brief          Resize down, keeping at least the specified number of limbs
  *
+ *                 If \c X is smaller than \c nblimbs, it is resized up
+ *                 instead.
+ *
  * \param X        MPI to shrink
  * \param nblimbs  The minimum number of limbs to keep
  *
  * \return         0 if successful,
  *                 MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed
+ *                 (this can only happen when resizing up).
  */
 int mbedtls_mpi_shrink( mbedtls_mpi *X, size_t nblimbs );
 
 /**
  * \brief          Copy the contents of Y into X
  *
- * \param X        Destination MPI
- * \param Y        Source MPI
+ * \param X        Destination MPI. It is enlarged if necessary.
+ * \param Y        Source MPI.
  *
  * \return         0 if successful,
  *                 MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed
@@ -683,6 +690,10 @@
  *
  * \return         0 if successful,
  *                 MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed
+ *
+ * \note           The bytes obtained from the PRNG are interpreted
+ *                 as a big-endian representation of an MPI; this can
+ *                 be relevant in applications like deterministic ECDSA.
  */
 int mbedtls_mpi_fill_random( mbedtls_mpi *X, size_t size,
                      int (*f_rng)(void *, unsigned char *, size_t),
@@ -714,8 +725,18 @@
  */
 int mbedtls_mpi_inv_mod( mbedtls_mpi *X, const mbedtls_mpi *A, const mbedtls_mpi *N );
 
+#if !defined(MBEDTLS_DEPRECATED_REMOVED)
+#if defined(MBEDTLS_DEPRECATED_WARNING)
+#define MBEDTLS_DEPRECATED      __attribute__((deprecated))
+#else
+#define MBEDTLS_DEPRECATED
+#endif
 /**
- * \brief          Miller-Rabin primality test
+ * \brief          Miller-Rabin primality test with error probability of
+ *                 2<sup>-80</sup>
+ *
+ * \deprecated     Superseded by mbedtls_mpi_is_prime_ext() which allows
+ *                 specifying the number of Miller-Rabin rounds.
  *
  * \param X        MPI to check
  * \param f_rng    RNG function
@@ -725,9 +746,48 @@
  *                 MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed,
  *                 MBEDTLS_ERR_MPI_NOT_ACCEPTABLE if X is not prime
  */
-int mbedtls_mpi_is_prime( const mbedtls_mpi *X,
-                  int (*f_rng)(void *, unsigned char *, size_t),
-                  void *p_rng );
+MBEDTLS_DEPRECATED int mbedtls_mpi_is_prime( const mbedtls_mpi *X,
+                          int (*f_rng)(void *, unsigned char *, size_t),
+                          void *p_rng );
+#undef MBEDTLS_DEPRECATED
+#endif /* !MBEDTLS_DEPRECATED_REMOVED */
+
+/**
+ * \brief          Miller-Rabin primality test.
+ *
+ * \warning        If \p X is potentially generated by an adversary, for example
+ *                 when validating cryptographic parameters that you didn't
+ *                 generate yourself and that are supposed to be prime, then
+ *                 \p rounds should be at least the half of the security
+ *                 strength of the cryptographic algorithm. On the other hand,
+ *                 if \p X is chosen uniformly or non-adversially (as is the
+ *                 case when mbedtls_mpi_gen_prime calls this function), then
+ *                 \p rounds can be much lower.
+ *
+ * \param X        MPI to check
+ * \param rounds   Number of bases to perform Miller-Rabin primality test for.
+ *                 The probability of returning 0 on a composite is at most
+ *                 2<sup>-2*\p rounds</sup>.
+ * \param f_rng    RNG function
+ * \param p_rng    RNG parameter
+ *
+ * \return         0 if successful (probably prime),
+ *                 MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed,
+ *                 MBEDTLS_ERR_MPI_NOT_ACCEPTABLE if X is not prime
+ */
+int mbedtls_mpi_is_prime_ext( const mbedtls_mpi *X, int rounds,
+                              int (*f_rng)(void *, unsigned char *, size_t),
+                              void *p_rng );
+/**
+ * \brief Flags for mbedtls_mpi_gen_prime()
+ *
+ * Each of these flags is a constraint on the result X returned by
+ * mbedtls_mpi_gen_prime().
+ */
+typedef enum {
+    MBEDTLS_MPI_GEN_PRIME_FLAG_DH =      0x0001, /**< (X-1)/2 is prime too */
+    MBEDTLS_MPI_GEN_PRIME_FLAG_LOW_ERR = 0x0002, /**< lower error rate from 2<sup>-80</sup> to 2<sup>-128</sup> */
+} mbedtls_mpi_gen_prime_flag_t;
 
 /**
  * \brief          Prime number generation
@@ -735,7 +795,7 @@
  * \param X        Destination MPI
  * \param nbits    Required size of X in bits
  *                 ( 3 <= nbits <= MBEDTLS_MPI_MAX_BITS )
- * \param dh_flag  If 1, then (X-1)/2 will be prime too
+ * \param flags    Mask of flags of type #mbedtls_mpi_gen_prime_flag_t
  * \param f_rng    RNG function
  * \param p_rng    RNG parameter
  *
@@ -743,7 +803,7 @@
  *                 MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed,
  *                 MBEDTLS_ERR_MPI_BAD_INPUT_DATA if nbits is < 3
  */
-int mbedtls_mpi_gen_prime( mbedtls_mpi *X, size_t nbits, int dh_flag,
+int mbedtls_mpi_gen_prime( mbedtls_mpi *X, size_t nbits, int flags,
                    int (*f_rng)(void *, unsigned char *, size_t),
                    void *p_rng );
 
diff --git a/ext/mbedtls/include/mbedtls/check_config.h b/ext/mbedtls/include/mbedtls/check_config.h
index fa72454..425e3ea 100644
--- a/ext/mbedtls/include/mbedtls/check_config.h
+++ b/ext/mbedtls/include/mbedtls/check_config.h
@@ -2,8 +2,9 @@
  * \file check_config.h
  *
  * \brief Consistency checks for configuration options
- *
- *  Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
+ */
+/*
+ *  Copyright (C) 2006-2018, ARM Limited, All Rights Reserved
  *  SPDX-License-Identifier: Apache-2.0
  *
  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
@@ -77,11 +78,20 @@
 #error "MBEDTLS_DHM_C defined, but not all prerequisites"
 #endif
 
+#if defined(MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT) && !defined(MBEDTLS_SSL_TRUNCATED_HMAC)
+#error "MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT defined, but not all prerequisites"
+#endif
+
 #if defined(MBEDTLS_CMAC_C) && \
     !defined(MBEDTLS_AES_C) && !defined(MBEDTLS_DES_C)
 #error "MBEDTLS_CMAC_C defined, but not all prerequisites"
 #endif
 
+#if defined(MBEDTLS_NIST_KW_C) && \
+    ( !defined(MBEDTLS_AES_C) || !defined(MBEDTLS_CIPHER_C) )
+#error "MBEDTLS_NIST_KW_C defined, but not all prerequisites"
+#endif
+
 #if defined(MBEDTLS_ECDH_C) && !defined(MBEDTLS_ECP_C)
 #error "MBEDTLS_ECDH_C defined, but not all prerequisites"
 #endif
@@ -98,6 +108,16 @@
 #error "MBEDTLS_ECJPAKE_C defined, but not all prerequisites"
 #endif
 
+#if defined(MBEDTLS_ECP_RESTARTABLE)           && \
+    ( defined(MBEDTLS_ECDH_COMPUTE_SHARED_ALT) || \
+      defined(MBEDTLS_ECDH_GEN_PUBLIC_ALT)     || \
+      defined(MBEDTLS_ECDSA_SIGN_ALT)          || \
+      defined(MBEDTLS_ECDSA_VERIFY_ALT)        || \
+      defined(MBEDTLS_ECDSA_GENKEY_ALT)        || \
+      defined(MBEDTLS_ECP_ALT) )
+#error "MBEDTLS_ECP_RESTARTABLE defined, but it cannot coexist with an alternative ECP implementation"
+#endif
+
 #if defined(MBEDTLS_ECDSA_DETERMINISTIC) && !defined(MBEDTLS_HMAC_DRBG_C)
 #error "MBEDTLS_ECDSA_DETERMINISTIC defined, but not all prerequisites"
 #endif
@@ -186,6 +206,10 @@
 #error "MBEDTLS_HAVEGE_C defined, but not all prerequisites"
 #endif
 
+#if defined(MBEDTLS_HKDF_C) && !defined(MBEDTLS_MD_C)
+#error "MBEDTLS_HKDF_C defined, but not all prerequisites"
+#endif
+
 #if defined(MBEDTLS_HMAC_DRBG_C) && !defined(MBEDTLS_MD_C)
 #error "MBEDTLS_HMAC_DRBG_C defined, but not all prerequisites"
 #endif
diff --git a/ext/mbedtls/include/mbedtls/ecdsa.h b/ext/mbedtls/include/mbedtls/ecdsa.h
index a277715..4057828 100644
--- a/ext/mbedtls/include/mbedtls/ecdsa.h
+++ b/ext/mbedtls/include/mbedtls/ecdsa.h
@@ -1,9 +1,17 @@
 /**
  * \file ecdsa.h
  *
- * \brief Elliptic curve DSA
+ * \brief This file contains ECDSA definitions and functions.
  *
- *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ * The Elliptic Curve Digital Signature Algorithm (ECDSA) is defined in
+ * <em>Standards for Efficient Cryptography Group (SECG):
+ * SEC1 Elliptic Curve Cryptography</em>.
+ * The use of ECDSA for TLS is defined in <em>RFC-4492: Elliptic Curve
+ * Cryptography (ECC) Cipher Suites for Transport Layer Security (TLS)</em>.
+ *
+ */
+/*
+ *  Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved
  *  SPDX-License-Identifier: Apache-2.0
  *
  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
@@ -18,8 +26,9 @@
  *  See the License for the specific language governing permissions and
  *  limitations under the License.
  *
- *  This file is part of mbed TLS (https://tls.mbed.org)
+ *  This file is part of Mbed TLS (https://tls.mbed.org)
  */
+
 #ifndef MBEDTLS_ECDSA_H
 #define MBEDTLS_ECDSA_H
 
@@ -27,7 +36,7 @@
 #include "md.h"
 
 /*
- * RFC 4492 page 20:
+ * RFC-4492 page 20:
  *
  *     Ecdsa-Sig-Value ::= SEQUENCE {
  *         r       INTEGER,
@@ -43,38 +52,94 @@
 #if MBEDTLS_ECP_MAX_BYTES > 124
 #error "MBEDTLS_ECP_MAX_BYTES bigger than expected, please fix MBEDTLS_ECDSA_MAX_LEN"
 #endif
-/** Maximum size of an ECDSA signature in bytes */
+/** The maximal size of an ECDSA signature in Bytes. */
 #define MBEDTLS_ECDSA_MAX_LEN  ( 3 + 2 * ( 3 + MBEDTLS_ECP_MAX_BYTES ) )
 
-/**
- * \brief           ECDSA context structure
- */
-typedef mbedtls_ecp_keypair mbedtls_ecdsa_context;
-
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 /**
- * \brief           Compute ECDSA signature of a previously hashed message
+ * \brief           The ECDSA context structure.
  *
- * \note            The deterministic version is usually prefered.
+ * \warning         Performing multiple operations concurrently on the same
+ *                  ECDSA context is not supported; objects of this type
+ *                  should not be shared between multiple threads.
+ */
+typedef mbedtls_ecp_keypair mbedtls_ecdsa_context;
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+
+/**
+ * \brief           Internal restart context for ecdsa_verify()
  *
- * \param grp       ECP group
- * \param r         First output integer
- * \param s         Second output integer
- * \param d         Private signing key
- * \param buf       Message hash
- * \param blen      Length of buf
- * \param f_rng     RNG function
- * \param p_rng     RNG parameter
+ * \note            Opaque struct, defined in ecdsa.c
+ */
+typedef struct mbedtls_ecdsa_restart_ver mbedtls_ecdsa_restart_ver_ctx;
+
+/**
+ * \brief           Internal restart context for ecdsa_sign()
+ *
+ * \note            Opaque struct, defined in ecdsa.c
+ */
+typedef struct mbedtls_ecdsa_restart_sig mbedtls_ecdsa_restart_sig_ctx;
+
+#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
+/**
+ * \brief           Internal restart context for ecdsa_sign_det()
+ *
+ * \note            Opaque struct, defined in ecdsa.c
+ */
+typedef struct mbedtls_ecdsa_restart_det mbedtls_ecdsa_restart_det_ctx;
+#endif
+
+/**
+ * \brief           General context for resuming ECDSA operations
+ */
+typedef struct
+{
+    mbedtls_ecp_restart_ctx ecp;        /*!<  base context for ECP restart and
+                                              shared administrative info    */
+    mbedtls_ecdsa_restart_ver_ctx *ver; /*!<  ecdsa_verify() sub-context    */
+    mbedtls_ecdsa_restart_sig_ctx *sig; /*!<  ecdsa_sign() sub-context      */
+#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
+    mbedtls_ecdsa_restart_det_ctx *det; /*!<  ecdsa_sign_det() sub-context  */
+#endif
+} mbedtls_ecdsa_restart_ctx;
+
+#else /* MBEDTLS_ECP_RESTARTABLE */
+
+/* Now we can declare functions that take a pointer to that */
+typedef void mbedtls_ecdsa_restart_ctx;
+
+#endif /* MBEDTLS_ECP_RESTARTABLE */
+
+/**
+ * \brief           This function computes the ECDSA signature of a
+ *                  previously-hashed message.
+ *
+ * \note            The deterministic version is usually preferred.
  *
  * \note            If the bitlength of the message hash is larger than the
- *                  bitlength of the group order, then the hash is truncated as
- *                  prescribed by SEC1 4.1.3 step 5.
+ *                  bitlength of the group order, then the hash is truncated
+ *                  as defined in <em>Standards for Efficient Cryptography Group
+ *                  (SECG): SEC1 Elliptic Curve Cryptography</em>, section
+ *                  4.1.3, step 5.
  *
- * \return          0 if successful,
- *                  or a MBEDTLS_ERR_ECP_XXX or MBEDTLS_MPI_XXX error code
+ * \see             ecp.h
+ *
+ * \param grp       The ECP group.
+ * \param r         The first output integer.
+ * \param s         The second output integer.
+ * \param d         The private signing key.
+ * \param buf       The message hash.
+ * \param blen      The length of \p buf.
+ * \param f_rng     The RNG function.
+ * \param p_rng     The RNG context.
+ *
+ * \return          \c 0 on success.
+ * \return          An \c MBEDTLS_ERR_ECP_XXX
+ *                  or \c MBEDTLS_MPI_XXX error code on failure.
  */
 int mbedtls_ecdsa_sign( mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s,
                 const mbedtls_mpi *d, const unsigned char *buf, size_t blen,
@@ -82,23 +147,32 @@
 
 #if defined(MBEDTLS_ECDSA_DETERMINISTIC)
 /**
- * \brief           Compute ECDSA signature of a previously hashed message,
- *                  deterministic version (RFC 6979).
+ * \brief           This function computes the ECDSA signature of a
+ *                  previously-hashed message, deterministic version.
  *
- * \param grp       ECP group
- * \param r         First output integer
- * \param s         Second output integer
- * \param d         Private signing key
- * \param buf       Message hash
- * \param blen      Length of buf
- * \param md_alg    MD algorithm used to hash the message
+ *                  For more information, see <em>RFC-6979: Deterministic
+ *                  Usage of the Digital Signature Algorithm (DSA) and Elliptic
+ *                  Curve Digital Signature Algorithm (ECDSA)</em>.
  *
  * \note            If the bitlength of the message hash is larger than the
  *                  bitlength of the group order, then the hash is truncated as
- *                  prescribed by SEC1 4.1.3 step 5.
+ *                  defined in <em>Standards for Efficient Cryptography Group
+ *                  (SECG): SEC1 Elliptic Curve Cryptography</em>, section
+ *                  4.1.3, step 5.
  *
- * \return          0 if successful,
- *                  or a MBEDTLS_ERR_ECP_XXX or MBEDTLS_MPI_XXX error code
+ * \see             ecp.h
+ *
+ * \param grp       The ECP group.
+ * \param r         The first output integer.
+ * \param s         The second output integer.
+ * \param d         The private signing key.
+ * \param buf       The message hash.
+ * \param blen      The length of \p buf.
+ * \param md_alg    The MD algorithm used to hash the message.
+ *
+ * \return          \c 0 on success.
+ * \return          An \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_MPI_XXX
+ *                  error code on failure.
  */
 int mbedtls_ecdsa_sign_det( mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s,
                     const mbedtls_mpi *d, const unsigned char *buf, size_t blen,
@@ -106,55 +180,74 @@
 #endif /* MBEDTLS_ECDSA_DETERMINISTIC */
 
 /**
- * \brief           Verify ECDSA signature of a previously hashed message
- *
- * \param grp       ECP group
- * \param buf       Message hash
- * \param blen      Length of buf
- * \param Q         Public key to use for verification
- * \param r         First integer of the signature
- * \param s         Second integer of the signature
+ * \brief           This function verifies the ECDSA signature of a
+ *                  previously-hashed message.
  *
  * \note            If the bitlength of the message hash is larger than the
  *                  bitlength of the group order, then the hash is truncated as
- *                  prescribed by SEC1 4.1.4 step 3.
+ *                  defined in <em>Standards for Efficient Cryptography Group
+ *                  (SECG): SEC1 Elliptic Curve Cryptography</em>, section
+ *                  4.1.4, step 3.
  *
- * \return          0 if successful,
- *                  MBEDTLS_ERR_ECP_BAD_INPUT_DATA if signature is invalid
- *                  or a MBEDTLS_ERR_ECP_XXX or MBEDTLS_MPI_XXX error code
+ * \see             ecp.h
+ *
+ * \param grp       The ECP group.
+ * \param buf       The message hash.
+ * \param blen      The length of \p buf.
+ * \param Q         The public key to use for verification.
+ * \param r         The first integer of the signature.
+ * \param s         The second integer of the signature.
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if the signature
+ *                  is invalid.
+ * \return          An \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_MPI_XXX
+ *                  error code on failure for any other reason.
  */
 int mbedtls_ecdsa_verify( mbedtls_ecp_group *grp,
                   const unsigned char *buf, size_t blen,
                   const mbedtls_ecp_point *Q, const mbedtls_mpi *r, const mbedtls_mpi *s);
 
 /**
- * \brief           Compute ECDSA signature and write it to buffer,
- *                  serialized as defined in RFC 4492 page 20.
- *                  (Not thread-safe to use same context in multiple threads)
+ * \brief           This function computes the ECDSA signature and writes it
+ *                  to a buffer, serialized as defined in <em>RFC-4492:
+ *                  Elliptic Curve Cryptography (ECC) Cipher Suites for
+ *                  Transport Layer Security (TLS)</em>.
  *
- * \note            The deterministic version (RFC 6979) is used if
- *                  MBEDTLS_ECDSA_DETERMINISTIC is defined.
+ * \warning         It is not thread-safe to use the same context in
+ *                  multiple threads.
  *
- * \param ctx       ECDSA context
- * \param md_alg    Algorithm that was used to hash the message
- * \param hash      Message hash
- * \param hlen      Length of hash
- * \param sig       Buffer that will hold the signature
- * \param slen      Length of the signature written
- * \param f_rng     RNG function
- * \param p_rng     RNG parameter
+ * \note            The deterministic version is used if
+ *                  #MBEDTLS_ECDSA_DETERMINISTIC is defined. For more
+ *                  information, see <em>RFC-6979: Deterministic Usage
+ *                  of the Digital Signature Algorithm (DSA) and Elliptic
+ *                  Curve Digital Signature Algorithm (ECDSA)</em>.
  *
- * \note            The "sig" buffer must be at least as large as twice the
- *                  size of the curve used, plus 9 (eg. 73 bytes if a 256-bit
- *                  curve is used). MBEDTLS_ECDSA_MAX_LEN is always safe.
+ * \note            The \p sig buffer must be at least twice as large as the
+ *                  size of the curve used, plus 9. For example, 73 Bytes if
+ *                  a 256-bit curve is used. A buffer length of
+ *                  #MBEDTLS_ECDSA_MAX_LEN is always safe.
  *
  * \note            If the bitlength of the message hash is larger than the
  *                  bitlength of the group order, then the hash is truncated as
- *                  prescribed by SEC1 4.1.3 step 5.
+ *                  defined in <em>Standards for Efficient Cryptography Group
+ *                  (SECG): SEC1 Elliptic Curve Cryptography</em>, section
+ *                  4.1.3, step 5.
  *
- * \return          0 if successful,
- *                  or a MBEDTLS_ERR_ECP_XXX, MBEDTLS_ERR_MPI_XXX or
- *                  MBEDTLS_ERR_ASN1_XXX error code
+ * \see             ecp.h
+ *
+ * \param ctx       The ECDSA context.
+ * \param md_alg    The message digest that was used to hash the message.
+ * \param hash      The message hash.
+ * \param hlen      The length of the hash.
+ * \param sig       The buffer that holds the signature.
+ * \param slen      The length of the signature written.
+ * \param f_rng     The RNG function.
+ * \param p_rng     The RNG context.
+ *
+ * \return          \c 0 on success.
+ * \return          An \c MBEDTLS_ERR_ECP_XXX, \c MBEDTLS_ERR_MPI_XXX or
+ *                  \c MBEDTLS_ERR_ASN1_XXX error code on failure.
  */
 int mbedtls_ecdsa_write_signature( mbedtls_ecdsa_context *ctx, mbedtls_md_type_t md_alg,
                            const unsigned char *hash, size_t hlen,
@@ -162,6 +255,40 @@
                            int (*f_rng)(void *, unsigned char *, size_t),
                            void *p_rng );
 
+/**
+ * \brief           This function computes the ECDSA signature and writes it
+ *                  to a buffer, in a restartable way.
+ *
+ * \see             \c mbedtls_ecdsa_write_signature()
+ *
+ * \note            This function is like \c mbedtls_ecdsa_write_signature()
+ *                  but it can return early and restart according to the limit
+ *                  set with \c mbedtls_ecp_set_max_ops() to reduce blocking.
+ *
+ * \param ctx       The ECDSA context.
+ * \param md_alg    The message digest that was used to hash the message.
+ * \param hash      The message hash.
+ * \param hlen      The length of the hash.
+ * \param sig       The buffer that holds the signature.
+ * \param slen      The length of the signature written.
+ * \param f_rng     The RNG function.
+ * \param p_rng     The RNG context.
+ * \param rs_ctx    The restart context (NULL disables restart).
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
+ *                  operations was reached: see \c mbedtls_ecp_set_max_ops().
+ * \return          Another \c MBEDTLS_ERR_ECP_XXX, \c MBEDTLS_ERR_MPI_XXX or
+ *                  \c MBEDTLS_ERR_ASN1_XXX error code on failure.
+ */
+int mbedtls_ecdsa_write_signature_restartable( mbedtls_ecdsa_context *ctx,
+                           mbedtls_md_type_t md_alg,
+                           const unsigned char *hash, size_t hlen,
+                           unsigned char *sig, size_t *slen,
+                           int (*f_rng)(void *, unsigned char *, size_t),
+                           void *p_rng,
+                           mbedtls_ecdsa_restart_ctx *rs_ctx );
+
 #if defined(MBEDTLS_ECDSA_DETERMINISTIC)
 #if ! defined(MBEDTLS_DEPRECATED_REMOVED)
 #if defined(MBEDTLS_DEPRECATED_WARNING)
@@ -170,31 +297,44 @@
 #define MBEDTLS_DEPRECATED
 #endif
 /**
- * \brief           Compute ECDSA signature and write it to buffer,
- *                  serialized as defined in RFC 4492 page 20.
- *                  Deterministic version, RFC 6979.
- *                  (Not thread-safe to use same context in multiple threads)
+ * \brief           This function computes an ECDSA signature and writes
+ *                  it to a buffer, serialized as defined in <em>RFC-4492:
+ *                  Elliptic Curve Cryptography (ECC) Cipher Suites for
+ *                  Transport Layer Security (TLS)</em>.
  *
- * \deprecated      Superseded by mbedtls_ecdsa_write_signature() in 2.0.0
+ *                  The deterministic version is defined in <em>RFC-6979:
+ *                  Deterministic Usage of the Digital Signature Algorithm (DSA)
+ *                  and Elliptic Curve Digital Signature Algorithm (ECDSA)</em>.
  *
- * \param ctx       ECDSA context
- * \param hash      Message hash
- * \param hlen      Length of hash
- * \param sig       Buffer that will hold the signature
- * \param slen      Length of the signature written
- * \param md_alg    MD algorithm used to hash the message
+ * \warning         It is not thread-safe to use the same context in
+ *                  multiple threads.
  *
- * \note            The "sig" buffer must be at least as large as twice the
- *                  size of the curve used, plus 9 (eg. 73 bytes if a 256-bit
- *                  curve is used). MBEDTLS_ECDSA_MAX_LEN is always safe.
+ * \note            The \p sig buffer must be at least twice as large as the
+ *                  size of the curve used, plus 9. For example, 73 Bytes if a
+ *                  256-bit curve is used. A buffer length of
+ *                  #MBEDTLS_ECDSA_MAX_LEN is always safe.
  *
  * \note            If the bitlength of the message hash is larger than the
  *                  bitlength of the group order, then the hash is truncated as
- *                  prescribed by SEC1 4.1.3 step 5.
+ *                  defined in <em>Standards for Efficient Cryptography Group
+ *                  (SECG): SEC1 Elliptic Curve Cryptography</em>, section
+ *                  4.1.3, step 5.
  *
- * \return          0 if successful,
- *                  or a MBEDTLS_ERR_ECP_XXX, MBEDTLS_ERR_MPI_XXX or
- *                  MBEDTLS_ERR_ASN1_XXX error code
+ * \see             ecp.h
+ *
+ * \deprecated      Superseded by mbedtls_ecdsa_write_signature() in
+ *                  Mbed TLS version 2.0 and later.
+ *
+ * \param ctx       The ECDSA context.
+ * \param hash      The message hash.
+ * \param hlen      The length of the hash.
+ * \param sig       The buffer that holds the signature.
+ * \param slen      The length of the signature written.
+ * \param md_alg    The MD algorithm used to hash the message.
+ *
+ * \return          \c 0 on success.
+ * \return          An \c MBEDTLS_ERR_ECP_XXX, \c MBEDTLS_ERR_MPI_XXX or
+ *                  \c MBEDTLS_ERR_ASN1_XXX error code on failure.
  */
 int mbedtls_ecdsa_write_signature_det( mbedtls_ecdsa_context *ctx,
                                const unsigned char *hash, size_t hlen,
@@ -205,66 +345,120 @@
 #endif /* MBEDTLS_ECDSA_DETERMINISTIC */
 
 /**
- * \brief           Read and verify an ECDSA signature
- *
- * \param ctx       ECDSA context
- * \param hash      Message hash
- * \param hlen      Size of hash
- * \param sig       Signature to read and verify
- * \param slen      Size of sig
+ * \brief           This function reads and verifies an ECDSA signature.
  *
  * \note            If the bitlength of the message hash is larger than the
  *                  bitlength of the group order, then the hash is truncated as
- *                  prescribed by SEC1 4.1.4 step 3.
+ *                  defined in <em>Standards for Efficient Cryptography Group
+ *                  (SECG): SEC1 Elliptic Curve Cryptography</em>, section
+ *                  4.1.4, step 3.
  *
- * \return          0 if successful,
- *                  MBEDTLS_ERR_ECP_BAD_INPUT_DATA if signature is invalid,
- *                  MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH if the signature is
- *                  valid but its actual length is less than siglen,
- *                  or a MBEDTLS_ERR_ECP_XXX or MBEDTLS_ERR_MPI_XXX error code
+ * \see             ecp.h
+ *
+ * \param ctx       The ECDSA context.
+ * \param hash      The message hash.
+ * \param hlen      The size of the hash.
+ * \param sig       The signature to read and verify.
+ * \param slen      The size of \p sig.
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if signature is invalid.
+ * \return          #MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH if there is a valid
+ *                  signature in \p sig, but its length is less than \p siglen.
+ * \return          An \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_ERR_MPI_XXX
+ *                  error code on failure for any other reason.
  */
 int mbedtls_ecdsa_read_signature( mbedtls_ecdsa_context *ctx,
                           const unsigned char *hash, size_t hlen,
                           const unsigned char *sig, size_t slen );
 
 /**
- * \brief           Generate an ECDSA keypair on the given curve
+ * \brief           This function reads and verifies an ECDSA signature,
+ *                  in a restartable way.
  *
- * \param ctx       ECDSA context in which the keypair should be stored
- * \param gid       Group (elliptic curve) to use. One of the various
- *                  MBEDTLS_ECP_DP_XXX macros depending on configuration.
- * \param f_rng     RNG function
- * \param p_rng     RNG parameter
+ * \see             \c mbedtls_ecdsa_read_signature()
  *
- * \return          0 on success, or a MBEDTLS_ERR_ECP_XXX code.
+ * \note            This function is like \c mbedtls_ecdsa_read_signature()
+ *                  but it can return early and restart according to the limit
+ *                  set with \c mbedtls_ecp_set_max_ops() to reduce blocking.
+ *
+ * \param ctx       The ECDSA context.
+ * \param hash      The message hash.
+ * \param hlen      The size of the hash.
+ * \param sig       The signature to read and verify.
+ * \param slen      The size of \p sig.
+ * \param rs_ctx    The restart context (NULL disables restart).
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if signature is invalid.
+ * \return          #MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH if there is a valid
+ *                  signature in \p sig, but its length is less than \p siglen.
+ * \return          #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
+ *                  operations was reached: see \c mbedtls_ecp_set_max_ops().
+ * \return          Another \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_ERR_MPI_XXX
+ *                  error code on failure for any other reason.
+ */
+int mbedtls_ecdsa_read_signature_restartable( mbedtls_ecdsa_context *ctx,
+                          const unsigned char *hash, size_t hlen,
+                          const unsigned char *sig, size_t slen,
+                          mbedtls_ecdsa_restart_ctx *rs_ctx );
+
+/**
+ * \brief          This function generates an ECDSA keypair on the given curve.
+ *
+ * \see            ecp.h
+ *
+ * \param ctx      The ECDSA context to store the keypair in.
+ * \param gid      The elliptic curve to use. One of the various
+ *                 \c MBEDTLS_ECP_DP_XXX macros depending on configuration.
+ * \param f_rng    The RNG function.
+ * \param p_rng    The RNG context.
+ *
+ * \return         \c 0 on success.
+ * \return         An \c MBEDTLS_ERR_ECP_XXX code on failure.
  */
 int mbedtls_ecdsa_genkey( mbedtls_ecdsa_context *ctx, mbedtls_ecp_group_id gid,
                   int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
 
 /**
- * \brief           Set an ECDSA context from an EC key pair
+ * \brief           This function sets an ECDSA context from an EC key pair.
  *
- * \param ctx       ECDSA context to set
- * \param key       EC key to use
+ * \see             ecp.h
  *
- * \return          0 on success, or a MBEDTLS_ERR_ECP_XXX code.
+ * \param ctx       The ECDSA context to set.
+ * \param key       The EC key to use.
+ *
+ * \return          \c 0 on success.
+ * \return          An \c MBEDTLS_ERR_ECP_XXX code on failure.
  */
 int mbedtls_ecdsa_from_keypair( mbedtls_ecdsa_context *ctx, const mbedtls_ecp_keypair *key );
 
 /**
- * \brief           Initialize context
+ * \brief           This function initializes an ECDSA context.
  *
- * \param ctx       Context to initialize
+ * \param ctx       The ECDSA context to initialize.
  */
 void mbedtls_ecdsa_init( mbedtls_ecdsa_context *ctx );
 
 /**
- * \brief           Free context
+ * \brief           This function frees an ECDSA context.
  *
- * \param ctx       Context to free
+ * \param ctx       The ECDSA context to free.
  */
 void mbedtls_ecdsa_free( mbedtls_ecdsa_context *ctx );
 
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+/**
+ * \brief           Initialize a restart context
+ */
+void mbedtls_ecdsa_restart_init( mbedtls_ecdsa_restart_ctx *ctx );
+
+/**
+ * \brief           Free the components of a restart context
+ */
+void mbedtls_ecdsa_restart_free( mbedtls_ecdsa_restart_ctx *ctx );
+#endif /* MBEDTLS_ECP_RESTARTABLE */
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/ext/mbedtls/include/mbedtls/ecp.h b/ext/mbedtls/include/mbedtls/ecp.h
index dad9aef..2fb1af4 100644
--- a/ext/mbedtls/include/mbedtls/ecp.h
+++ b/ext/mbedtls/include/mbedtls/ecp.h
@@ -1,9 +1,21 @@
 /**
  * \file ecp.h
  *
- * \brief Elliptic curves over GF(p)
+ * \brief This file provides an API for Elliptic Curves over GF(P) (ECP).
  *
- *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ * The use of ECP in cryptography and TLS is defined in
+ * <em>Standards for Efficient Cryptography Group (SECG): SEC1
+ * Elliptic Curve Cryptography</em> and
+ * <em>RFC-4492: Elliptic Curve Cryptography (ECC) Cipher Suites
+ * for Transport Layer Security (TLS)</em>.
+ *
+ * <em>RFC-2409: The Internet Key Exchange (IKE)</em> defines ECP
+ * group types.
+ *
+ */
+
+/*
+ *  Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved
  *  SPDX-License-Identifier: Apache-2.0
  *
  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
@@ -18,8 +30,9 @@
  *  See the License for the specific language governing permissions and
  *  limitations under the License.
  *
- *  This file is part of mbed TLS (https://tls.mbed.org)
+ *  This file is part of Mbed TLS (https://tls.mbed.org)
  */
+
 #ifndef MBEDTLS_ECP_H
 #define MBEDTLS_ECP_H
 
@@ -30,12 +43,85 @@
  */
 #define MBEDTLS_ERR_ECP_BAD_INPUT_DATA                    -0x4F80  /**< Bad input parameters to function. */
 #define MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL                  -0x4F00  /**< The buffer is too small to write to. */
-#define MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE               -0x4E80  /**< Requested curve not available. */
+#define MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE               -0x4E80  /**< The requested feature is not available, for example, the requested curve is not supported. */
 #define MBEDTLS_ERR_ECP_VERIFY_FAILED                     -0x4E00  /**< The signature is not valid. */
 #define MBEDTLS_ERR_ECP_ALLOC_FAILED                      -0x4D80  /**< Memory allocation failed. */
-#define MBEDTLS_ERR_ECP_RANDOM_FAILED                     -0x4D00  /**< Generation of random value, such as (ephemeral) key, failed. */
+#define MBEDTLS_ERR_ECP_RANDOM_FAILED                     -0x4D00  /**< Generation of random value, such as ephemeral key, failed. */
 #define MBEDTLS_ERR_ECP_INVALID_KEY                       -0x4C80  /**< Invalid private or public key. */
-#define MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH                  -0x4C00  /**< Signature is valid but shorter than the user-supplied length. */
+#define MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH                  -0x4C00  /**< The buffer contains a valid signature followed by more data. */
+
+/* MBEDTLS_ERR_ECP_HW_ACCEL_FAILED is deprecated and should not be used. */
+#define MBEDTLS_ERR_ECP_HW_ACCEL_FAILED                   -0x4B80  /**< The ECP hardware accelerator failed. */
+
+#define MBEDTLS_ERR_ECP_IN_PROGRESS                       -0x4B00  /**< Operation in progress, call again with the same parameters to continue. */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Domain-parameter identifiers: curve, subgroup, and generator.
+ *
+ * \note Only curves over prime fields are supported.
+ *
+ * \warning This library does not support validation of arbitrary domain
+ * parameters. Therefore, only standardized domain parameters from trusted
+ * sources should be used. See mbedtls_ecp_group_load().
+ */
+typedef enum
+{
+    MBEDTLS_ECP_DP_NONE = 0,       /*!< Curve not defined. */
+    MBEDTLS_ECP_DP_SECP192R1,      /*!< Domain parameters for the 192-bit curve defined by FIPS 186-4 and SEC1. */
+    MBEDTLS_ECP_DP_SECP224R1,      /*!< Domain parameters for the 224-bit curve defined by FIPS 186-4 and SEC1. */
+    MBEDTLS_ECP_DP_SECP256R1,      /*!< Domain parameters for the 256-bit curve defined by FIPS 186-4 and SEC1. */
+    MBEDTLS_ECP_DP_SECP384R1,      /*!< Domain parameters for the 384-bit curve defined by FIPS 186-4 and SEC1. */
+    MBEDTLS_ECP_DP_SECP521R1,      /*!< Domain parameters for the 521-bit curve defined by FIPS 186-4 and SEC1. */
+    MBEDTLS_ECP_DP_BP256R1,        /*!< Domain parameters for 256-bit Brainpool curve. */
+    MBEDTLS_ECP_DP_BP384R1,        /*!< Domain parameters for 384-bit Brainpool curve. */
+    MBEDTLS_ECP_DP_BP512R1,        /*!< Domain parameters for 512-bit Brainpool curve. */
+    MBEDTLS_ECP_DP_CURVE25519,     /*!< Domain parameters for Curve25519. */
+    MBEDTLS_ECP_DP_SECP192K1,      /*!< Domain parameters for 192-bit "Koblitz" curve. */
+    MBEDTLS_ECP_DP_SECP224K1,      /*!< Domain parameters for 224-bit "Koblitz" curve. */
+    MBEDTLS_ECP_DP_SECP256K1,      /*!< Domain parameters for 256-bit "Koblitz" curve. */
+    MBEDTLS_ECP_DP_CURVE448,       /*!< Domain parameters for Curve448. */
+} mbedtls_ecp_group_id;
+
+/**
+ * The number of supported curves, plus one for #MBEDTLS_ECP_DP_NONE.
+ *
+ * \note Montgomery curves are currently excluded.
+ */
+#define MBEDTLS_ECP_DP_MAX     12
+
+/**
+ * Curve information, for use by other modules.
+ */
+typedef struct mbedtls_ecp_curve_info
+{
+    mbedtls_ecp_group_id grp_id;    /*!< An internal identifier. */
+    uint16_t tls_id;                /*!< The TLS NamedCurve identifier. */
+    uint16_t bit_size;              /*!< The curve size in bits. */
+    const char *name;               /*!< A human-friendly name. */
+} mbedtls_ecp_curve_info;
+
+/**
+ * \brief           The ECP point structure, in Jacobian coordinates.
+ *
+ * \note            All functions expect and return points satisfying
+ *                  the following condition: <code>Z == 0</code> or
+ *                  <code>Z == 1</code>. Other values of \p Z are
+ *                  used only by internal functions.
+ *                  The point is zero, or "at infinity", if <code>Z == 0</code>.
+ *                  Otherwise, \p X and \p Y are its standard (affine)
+ *                  coordinates.
+ */
+typedef struct mbedtls_ecp_point
+{
+    mbedtls_mpi X;          /*!< The X coordinate of the ECP point. */
+    mbedtls_mpi Y;          /*!< The Y coordinate of the ECP point. */
+    mbedtls_mpi Z;          /*!< The Z coordinate of the ECP point. */
+}
+mbedtls_ecp_point;
 
 #if !defined(MBEDTLS_ECP_ALT)
 /*
@@ -46,143 +132,136 @@
  * one.)
  */
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 /**
- * Domain parameters (curve, subgroup and generator) identifiers.
+ * \brief           The ECP group structure.
  *
- * Only curves over prime fields are supported.
+ * We consider two types of curve equations:
+ * <ul><li>Short Weierstrass: <code>y^2 = x^3 + A x + B mod P</code>
+ * (SEC1 + RFC-4492)</li>
+ * <li>Montgomery: <code>y^2 = x^3 + A x^2 + x mod P</code> (Curve25519,
+ * Curve448)</li></ul>
+ * In both cases, the generator (\p G) for a prime-order subgroup is fixed.
  *
- * \warning This library does not support validation of arbitrary domain
- * parameters. Therefore, only well-known domain parameters from trusted
- * sources should be used. See mbedtls_ecp_group_load().
+ * For Short Weierstrass, this subgroup is the whole curve, and its
+ * cardinality is denoted by \p N. Our code requires that \p N is an
+ * odd prime as mbedtls_ecp_mul() requires an odd number, and
+ * mbedtls_ecdsa_sign() requires that it is prime for blinding purposes.
+ *
+ * For Montgomery curves, we do not store \p A, but <code>(A + 2) / 4</code>,
+ * which is the quantity used in the formulas. Additionally, \p nbits is
+ * not the size of \p N but the required size for private keys.
+ *
+ * If \p modp is NULL, reduction modulo \p P is done using a generic algorithm.
+ * Otherwise, \p modp must point to a function that takes an \p mbedtls_mpi in the
+ * range of <code>0..2^(2*pbits)-1</code>, and transforms it in-place to an integer
+ * which is congruent mod \p P to the given MPI, and is close enough to \p pbits
+ * in size, so that it may be efficiently brought in the 0..P-1 range by a few
+ * additions or subtractions. Therefore, it is only an approximative modular
+ * reduction. It must return 0 on success and non-zero on failure.
+ *
  */
-typedef enum
+typedef struct mbedtls_ecp_group
 {
-    MBEDTLS_ECP_DP_NONE = 0,
-    MBEDTLS_ECP_DP_SECP192R1,      /*!< 192-bits NIST curve  */
-    MBEDTLS_ECP_DP_SECP224R1,      /*!< 224-bits NIST curve  */
-    MBEDTLS_ECP_DP_SECP256R1,      /*!< 256-bits NIST curve  */
-    MBEDTLS_ECP_DP_SECP384R1,      /*!< 384-bits NIST curve  */
-    MBEDTLS_ECP_DP_SECP521R1,      /*!< 521-bits NIST curve  */
-    MBEDTLS_ECP_DP_BP256R1,        /*!< 256-bits Brainpool curve */
-    MBEDTLS_ECP_DP_BP384R1,        /*!< 384-bits Brainpool curve */
-    MBEDTLS_ECP_DP_BP512R1,        /*!< 512-bits Brainpool curve */
-    MBEDTLS_ECP_DP_CURVE25519,           /*!< Curve25519               */
-    MBEDTLS_ECP_DP_SECP192K1,      /*!< 192-bits "Koblitz" curve */
-    MBEDTLS_ECP_DP_SECP224K1,      /*!< 224-bits "Koblitz" curve */
-    MBEDTLS_ECP_DP_SECP256K1,      /*!< 256-bits "Koblitz" curve */
-} mbedtls_ecp_group_id;
-
-/**
- * Number of supported curves (plus one for NONE).
- *
- * (Montgomery curves excluded for now.)
- */
-#define MBEDTLS_ECP_DP_MAX     12
-
-/**
- * Curve information for use by other modules
- */
-typedef struct
-{
-    mbedtls_ecp_group_id grp_id;    /*!< Internal identifier        */
-    uint16_t tls_id;                /*!< TLS NamedCurve identifier  */
-    uint16_t bit_size;              /*!< Curve size in bits         */
-    const char *name;               /*!< Human-friendly name        */
-} mbedtls_ecp_curve_info;
-
-/**
- * \brief           ECP point structure (jacobian coordinates)
- *
- * \note            All functions expect and return points satisfying
- *                  the following condition: Z == 0 or Z == 1. (Other
- *                  values of Z are used by internal functions only.)
- *                  The point is zero, or "at infinity", if Z == 0.
- *                  Otherwise, X and Y are its standard (affine) coordinates.
- */
-typedef struct
-{
-    mbedtls_mpi X;          /*!<  the point's X coordinate  */
-    mbedtls_mpi Y;          /*!<  the point's Y coordinate  */
-    mbedtls_mpi Z;          /*!<  the point's Z coordinate  */
-}
-mbedtls_ecp_point;
-
-/**
- * \brief           ECP group structure
- *
- * We consider two types of curves equations:
- * 1. Short Weierstrass y^2 = x^3 + A x + B     mod P   (SEC1 + RFC 4492)
- * 2. Montgomery,       y^2 = x^3 + A x^2 + x   mod P   (Curve25519 + draft)
- * In both cases, a generator G for a prime-order subgroup is fixed. In the
- * short weierstrass, this subgroup is actually the whole curve, and its
- * cardinal is denoted by N.
- *
- * In the case of Short Weierstrass curves, our code requires that N is an odd
- * prime. (Use odd in mbedtls_ecp_mul() and prime in mbedtls_ecdsa_sign() for blinding.)
- *
- * In the case of Montgomery curves, we don't store A but (A + 2) / 4 which is
- * the quantity actually used in the formulas. Also, nbits is not the size of N
- * but the required size for private keys.
- *
- * If modp is NULL, reduction modulo P is done using a generic algorithm.
- * Otherwise, it must point to a function that takes an mbedtls_mpi in the range
- * 0..2^(2*pbits)-1 and transforms it in-place in an integer of little more
- * than pbits, so that the integer may be efficiently brought in the 0..P-1
- * range by a few additions or substractions. It must return 0 on success and
- * non-zero on failure.
- */
-typedef struct
-{
-    mbedtls_ecp_group_id id;    /*!<  internal group identifier                     */
-    mbedtls_mpi P;              /*!<  prime modulus of the base field               */
-    mbedtls_mpi A;              /*!<  1. A in the equation, or 2. (A + 2) / 4       */
-    mbedtls_mpi B;              /*!<  1. B in the equation, or 2. unused            */
-    mbedtls_ecp_point G;        /*!<  generator of the (sub)group used              */
-    mbedtls_mpi N;              /*!<  1. the order of G, or 2. unused               */
-    size_t pbits;       /*!<  number of bits in P                           */
-    size_t nbits;       /*!<  number of bits in 1. P, or 2. private keys    */
-    unsigned int h;     /*!<  internal: 1 if the constants are static       */
-    int (*modp)(mbedtls_mpi *); /*!<  function for fast reduction mod P             */
-    int (*t_pre)(mbedtls_ecp_point *, void *);  /*!< unused                         */
-    int (*t_post)(mbedtls_ecp_point *, void *); /*!< unused                         */
-    void *t_data;                       /*!< unused                         */
-    mbedtls_ecp_point *T;       /*!<  pre-computed points for ecp_mul_comb()        */
-    size_t T_size;      /*!<  number for pre-computed points                */
+    mbedtls_ecp_group_id id;    /*!< An internal group identifier. */
+    mbedtls_mpi P;              /*!< The prime modulus of the base field. */
+    mbedtls_mpi A;              /*!< For Short Weierstrass: \p A in the equation. For
+                                     Montgomery curves: <code>(A + 2) / 4</code>. */
+    mbedtls_mpi B;              /*!< For Short Weierstrass: \p B in the equation.
+                                     For Montgomery curves: unused. */
+    mbedtls_ecp_point G;        /*!< The generator of the subgroup used. */
+    mbedtls_mpi N;              /*!< The order of \p G. */
+    size_t pbits;               /*!< The number of bits in \p P.*/
+    size_t nbits;               /*!< For Short Weierstrass: The number of bits in \p P.
+                                     For Montgomery curves: the number of bits in the
+                                     private keys. */
+    unsigned int h;             /*!< \internal 1 if the constants are static. */
+    int (*modp)(mbedtls_mpi *); /*!< The function for fast pseudo-reduction
+                                     mod \p P (see above).*/
+    int (*t_pre)(mbedtls_ecp_point *, void *);  /*!< Unused. */
+    int (*t_post)(mbedtls_ecp_point *, void *); /*!< Unused. */
+    void *t_data;               /*!< Unused. */
+    mbedtls_ecp_point *T;       /*!< Pre-computed points for ecp_mul_comb(). */
+    size_t T_size;              /*!< The number of pre-computed points. */
 }
 mbedtls_ecp_group;
 
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+
 /**
- * \brief           ECP key pair structure
+ * \brief           Internal restart context for multiplication
  *
- * A generic key pair that could be used for ECDSA, fixed ECDH, etc.
+ * \note            Opaque struct
+ */
+typedef struct mbedtls_ecp_restart_mul mbedtls_ecp_restart_mul_ctx;
+
+/**
+ * \brief           Internal restart context for ecp_muladd()
  *
- * \note Members purposefully in the same order as struc mbedtls_ecdsa_context.
+ * \note            Opaque struct
+ */
+typedef struct mbedtls_ecp_restart_muladd mbedtls_ecp_restart_muladd_ctx;
+
+/**
+ * \brief           General context for resuming ECC operations
  */
 typedef struct
 {
-    mbedtls_ecp_group grp;      /*!<  Elliptic curve and base point     */
-    mbedtls_mpi d;              /*!<  our secret value                  */
-    mbedtls_ecp_point Q;        /*!<  our public value                  */
-}
-mbedtls_ecp_keypair;
+    unsigned ops_done;                  /*!<  current ops count             */
+    unsigned depth;                     /*!<  call depth (0 = top-level)    */
+    mbedtls_ecp_restart_mul_ctx *rsm;   /*!<  ecp_mul_comb() sub-context    */
+    mbedtls_ecp_restart_muladd_ctx *ma; /*!<  ecp_muladd() sub-context      */
+} mbedtls_ecp_restart_ctx;
+
+/*
+ * Operation counts for restartable functions
+ */
+#define MBEDTLS_ECP_OPS_CHK   3 /*!< basic ops count for ecp_check_pubkey()  */
+#define MBEDTLS_ECP_OPS_DBL   8 /*!< basic ops count for ecp_double_jac()    */
+#define MBEDTLS_ECP_OPS_ADD  11 /*!< basic ops count for see ecp_add_mixed() */
+#define MBEDTLS_ECP_OPS_INV 120 /*!< empirical equivalent for mpi_mod_inv()  */
+
+/**
+ * \brief           Internal; for restartable functions in other modules.
+ *                  Check and update basic ops budget.
+ *
+ * \param grp       Group structure
+ * \param rs_ctx    Restart context
+ * \param ops       Number of basic ops to do
+ *
+ * \return          \c 0 if doing \p ops basic ops is still allowed,
+ * \return          #MBEDTLS_ERR_ECP_IN_PROGRESS otherwise.
+ */
+int mbedtls_ecp_check_budget( const mbedtls_ecp_group *grp,
+                              mbedtls_ecp_restart_ctx *rs_ctx,
+                              unsigned ops );
+
+/* Utility macro for checking and updating ops budget */
+#define MBEDTLS_ECP_BUDGET( ops )   \
+    MBEDTLS_MPI_CHK( mbedtls_ecp_check_budget( grp, rs_ctx, \
+                                               (unsigned) (ops) ) );
+
+#else /* MBEDTLS_ECP_RESTARTABLE */
+
+#define MBEDTLS_ECP_BUDGET( ops )   /* no-op; for compatibility */
+
+/* We want to declare restartable versions of existing functions anyway */
+typedef void mbedtls_ecp_restart_ctx;
+
+#endif /* MBEDTLS_ECP_RESTARTABLE */
 
 /**
  * \name SECTION: Module settings
  *
  * The configuration options you can set for this module are in this section.
- * Either change them in config.h or define them on the compiler command line.
+ * Either change them in config.h, or define them using the compiler command line.
  * \{
  */
 
 #if !defined(MBEDTLS_ECP_MAX_BITS)
 /**
- * Maximum size of the groups (that is, of N and P)
+ * The maximum size of the groups, that is, of \c N and \c P.
  */
-#define MBEDTLS_ECP_MAX_BITS     521   /**< Maximum bit size of groups */
+#define MBEDTLS_ECP_MAX_BITS     521   /**< The maximum size of groups, in bits. */
 #endif
 
 #define MBEDTLS_ECP_MAX_BYTES    ( ( MBEDTLS_ECP_MAX_BITS + 7 ) / 8 )
@@ -205,11 +284,10 @@
  *      521       145     141     135     120      97
  *      384       214     209     198     177     146
  *      256       320     320     303     262     226
-
  *      224       475     475     453     398     342
  *      192       640     640     633     587     476
  */
-#define MBEDTLS_ECP_WINDOW_SIZE    6   /**< Maximum window size used */
+#define MBEDTLS_ECP_WINDOW_SIZE    6   /**< The maximum window size used. */
 #endif /* MBEDTLS_ECP_WINDOW_SIZE */
 
 #if !defined(MBEDTLS_ECP_FIXED_POINT_OPTIM)
@@ -224,33 +302,124 @@
  *
  * Change this value to 0 to reduce peak memory usage.
  */
-#define MBEDTLS_ECP_FIXED_POINT_OPTIM  1   /**< Enable fixed-point speed-up */
+#define MBEDTLS_ECP_FIXED_POINT_OPTIM  1   /**< Enable fixed-point speed-up. */
 #endif /* MBEDTLS_ECP_FIXED_POINT_OPTIM */
 
 /* \} name SECTION: Module settings */
 
+#else  /* MBEDTLS_ECP_ALT */
+#include "ecp_alt.h"
+#endif /* MBEDTLS_ECP_ALT */
+
+/**
+ * \brief    The ECP key-pair structure.
+ *
+ * A generic key-pair that may be used for ECDSA and fixed ECDH, for example.
+ *
+ * \note    Members are deliberately in the same order as in the
+ *          ::mbedtls_ecdsa_context structure.
+ */
+typedef struct mbedtls_ecp_keypair
+{
+    mbedtls_ecp_group grp;      /*!<  Elliptic curve and base point     */
+    mbedtls_mpi d;              /*!<  our secret value                  */
+    mbedtls_ecp_point Q;        /*!<  our public value                  */
+}
+mbedtls_ecp_keypair;
+
 /*
  * Point formats, from RFC 4492's enum ECPointFormat
  */
-#define MBEDTLS_ECP_PF_UNCOMPRESSED    0   /**< Uncompressed point format */
-#define MBEDTLS_ECP_PF_COMPRESSED      1   /**< Compressed point format */
+#define MBEDTLS_ECP_PF_UNCOMPRESSED    0   /**< Uncompressed point format. */
+#define MBEDTLS_ECP_PF_COMPRESSED      1   /**< Compressed point format. */
 
 /*
  * Some other constants from RFC 4492
  */
-#define MBEDTLS_ECP_TLS_NAMED_CURVE    3   /**< ECCurveType's named_curve */
+#define MBEDTLS_ECP_TLS_NAMED_CURVE    3   /**< The named_curve of ECCurveType. */
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+/**
+ * \brief           Set the maximum number of basic operations done in a row.
+ *
+ *                  If more operations are needed to complete a computation,
+ *                  #MBEDTLS_ERR_ECP_IN_PROGRESS will be returned by the
+ *                  function performing the computation. It is then the
+ *                  caller's responsibility to either call again with the same
+ *                  parameters until it returns 0 or an error code; or to free
+ *                  the restart context if the operation is to be aborted.
+ *
+ *                  It is strictly required that all input parameters and the
+ *                  restart context be the same on successive calls for the
+ *                  same operation, but output parameters need not be the
+ *                  same; they must not be used until the function finally
+ *                  returns 0.
+ *
+ *                  This only applies to functions whose documentation
+ *                  mentions they may return #MBEDTLS_ERR_ECP_IN_PROGRESS (or
+ *                  #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS for functions in the
+ *                  SSL module). For functions that accept a "restart context"
+ *                  argument, passing NULL disables restart and makes the
+ *                  function equivalent to the function with the same name
+ *                  with \c _restartable removed. For functions in the ECDH
+ *                  module, restart is disabled unless the function accepts
+ *                  an "ECDH context" argument and
+ *                  mbedtls_ecdh_enable_restart() was previously called on
+ *                  that context. For function in the SSL module, restart is
+ *                  only enabled for specific sides and key exchanges
+ *                  (currently only for clients and ECDHE-ECDSA).
+ *
+ * \param max_ops   Maximum number of basic operations done in a row.
+ *                  Default: 0 (unlimited).
+ *                  Lower (non-zero) values mean ECC functions will block for
+ *                  a lesser maximum amount of time.
+ *
+ * \note            A "basic operation" is defined as a rough equivalent of a
+ *                  multiplication in GF(p) for the NIST P-256 curve.
+ *                  As an indication, with default settings, a scalar
+ *                  multiplication (full run of \c mbedtls_ecp_mul()) is:
+ *                  - about 3300 basic operations for P-256
+ *                  - about 9400 basic operations for P-384
+ *
+ * \note            Very low values are not always respected: sometimes
+ *                  functions need to block for a minimum number of
+ *                  operations, and will do so even if max_ops is set to a
+ *                  lower value.  That minimum depends on the curve size, and
+ *                  can be made lower by decreasing the value of
+ *                  \c MBEDTLS_ECP_WINDOW_SIZE.  As an indication, here is the
+ *                  lowest effective value for various curves and values of
+ *                  that parameter (w for short):
+ *                          w=6     w=5     w=4     w=3     w=2
+ *                  P-256   208     208     160     136     124
+ *                  P-384   682     416     320     272     248
+ *                  P-521  1364     832     640     544     496
+ *
+ * \note            This setting is currently ignored by Curve25519.
+ */
+void mbedtls_ecp_set_max_ops( unsigned max_ops );
 
 /**
- * \brief           Get the list of supported curves in order of preferrence
- *                  (full information)
+ * \brief           Check if restart is enabled (max_ops != 0)
  *
- * \return          A statically allocated array, the last entry is 0.
+ * \return          \c 0 if \c max_ops == 0 (restart disabled)
+ * \return          \c 1 otherwise (restart enabled)
+ */
+int mbedtls_ecp_restart_is_enabled( void );
+#endif /* MBEDTLS_ECP_RESTARTABLE */
+
+/**
+ * \brief           This function retrieves the information defined in
+ *                  mbedtls_ecp_curve_info() for all supported curves in order
+ *                  of preference.
+ *
+ * \return          A statically allocated array. The last entry is 0.
  */
 const mbedtls_ecp_curve_info *mbedtls_ecp_curve_list( void );
 
 /**
- * \brief           Get the list of supported curves in order of preferrence
- *                  (grp_id only)
+ * \brief           This function retrieves the list of internal group
+ *                  identifiers of all supported curves in the order of
+ *                  preference.
  *
  * \return          A statically allocated array,
  *                  terminated with MBEDTLS_ECP_DP_NONE.
@@ -258,357 +427,492 @@
 const mbedtls_ecp_group_id *mbedtls_ecp_grp_id_list( void );
 
 /**
- * \brief           Get curve information from an internal group identifier
+ * \brief           This function retrieves curve information from an internal
+ *                  group identifier.
  *
- * \param grp_id    A MBEDTLS_ECP_DP_XXX value
+ * \param grp_id    An \c MBEDTLS_ECP_DP_XXX value.
  *
- * \return          The associated curve information or NULL
+ * \return          The associated curve information on success.
+ * \return          NULL on failure.
  */
 const mbedtls_ecp_curve_info *mbedtls_ecp_curve_info_from_grp_id( mbedtls_ecp_group_id grp_id );
 
 /**
- * \brief           Get curve information from a TLS NamedCurve value
+ * \brief           This function retrieves curve information from a TLS
+ *                  NamedCurve value.
  *
- * \param tls_id    A MBEDTLS_ECP_DP_XXX value
+ * \param tls_id    An \c MBEDTLS_ECP_DP_XXX value.
  *
- * \return          The associated curve information or NULL
+ * \return          The associated curve information on success.
+ * \return          NULL on failure.
  */
 const mbedtls_ecp_curve_info *mbedtls_ecp_curve_info_from_tls_id( uint16_t tls_id );
 
 /**
- * \brief           Get curve information from a human-readable name
+ * \brief           This function retrieves curve information from a
+ *                  human-readable name.
  *
- * \param name      The name
+ * \param name      The human-readable name.
  *
- * \return          The associated curve information or NULL
+ * \return          The associated curve information on success.
+ * \return          NULL on failure.
  */
 const mbedtls_ecp_curve_info *mbedtls_ecp_curve_info_from_name( const char *name );
 
 /**
- * \brief           Initialize a point (as zero)
+ * \brief           This function initializes a point as zero.
+ *
+ * \param pt        The point to initialize.
  */
 void mbedtls_ecp_point_init( mbedtls_ecp_point *pt );
 
 /**
- * \brief           Initialize a group (to something meaningless)
+ * \brief           This function initializes an ECP group context
+ *                  without loading any domain parameters.
+ *
+ * \note            After this function is called, domain parameters
+ *                  for various ECP groups can be loaded through the
+ *                  mbedtls_ecp_load() or mbedtls_ecp_tls_read_group()
+ *                  functions.
  */
 void mbedtls_ecp_group_init( mbedtls_ecp_group *grp );
 
 /**
- * \brief           Initialize a key pair (as an invalid one)
+ * \brief           This function initializes a key pair as an invalid one.
+ *
+ * \param key       The key pair to initialize.
  */
 void mbedtls_ecp_keypair_init( mbedtls_ecp_keypair *key );
 
 /**
- * \brief           Free the components of a point
+ * \brief           This function frees the components of a point.
+ *
+ * \param pt        The point to free.
  */
 void mbedtls_ecp_point_free( mbedtls_ecp_point *pt );
 
 /**
- * \brief           Free the components of an ECP group
+ * \brief           This function frees the components of an ECP group.
+ * \param grp       The group to free.
  */
 void mbedtls_ecp_group_free( mbedtls_ecp_group *grp );
 
 /**
- * \brief           Free the components of a key pair
+ * \brief           This function frees the components of a key pair.
+ * \param key       The key pair to free.
  */
 void mbedtls_ecp_keypair_free( mbedtls_ecp_keypair *key );
 
+#if defined(MBEDTLS_ECP_RESTARTABLE)
 /**
- * \brief           Copy the contents of point Q into P
+ * \brief           Initialize a restart context
+ */
+void mbedtls_ecp_restart_init( mbedtls_ecp_restart_ctx *ctx );
+
+/**
+ * \brief           Free the components of a restart context
+ */
+void mbedtls_ecp_restart_free( mbedtls_ecp_restart_ctx *ctx );
+#endif /* MBEDTLS_ECP_RESTARTABLE */
+
+/**
+ * \brief           This function copies the contents of point \p Q into
+ *                  point \p P.
  *
- * \param P         Destination point
- * \param Q         Source point
+ * \param P         The destination point.
+ * \param Q         The source point.
  *
- * \return          0 if successful,
- *                  MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
  */
 int mbedtls_ecp_copy( mbedtls_ecp_point *P, const mbedtls_ecp_point *Q );
 
 /**
- * \brief           Copy the contents of a group object
+ * \brief           This function copies the contents of group \p src into
+ *                  group \p dst.
  *
- * \param dst       Destination group
- * \param src       Source group
+ * \param dst       The destination group.
+ * \param src       The source group.
  *
- * \return          0 if successful,
- *                  MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
  */
 int mbedtls_ecp_group_copy( mbedtls_ecp_group *dst, const mbedtls_ecp_group *src );
 
 /**
- * \brief           Set a point to zero
+ * \brief           This function sets a point to zero.
  *
- * \param pt        Destination point
+ * \param pt        The point to set.
  *
- * \return          0 if successful,
- *                  MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
  */
 int mbedtls_ecp_set_zero( mbedtls_ecp_point *pt );
 
 /**
- * \brief           Tell if a point is zero
+ * \brief           This function checks if a point is zero.
  *
- * \param pt        Point to test
+ * \param pt        The point to test.
  *
- * \return          1 if point is zero, 0 otherwise
+ * \return          \c 1 if the point is zero.
+ * \return          \c 0 if the point is non-zero.
  */
 int mbedtls_ecp_is_zero( mbedtls_ecp_point *pt );
 
 /**
- * \brief           Compare two points
+ * \brief           This function compares two points.
  *
- * \note            This assumes the points are normalized. Otherwise,
+ * \note            This assumes that the points are normalized. Otherwise,
  *                  they may compare as "not equal" even if they are.
  *
- * \param P         First point to compare
- * \param Q         Second point to compare
+ * \param P         The first point to compare.
+ * \param Q         The second point to compare.
  *
- * \return          0 if the points are equal,
- *                  MBEDTLS_ERR_ECP_BAD_INPUT_DATA otherwise
+ * \return          \c 0 if the points are equal.
+ * \return          #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if the points are not equal.
  */
 int mbedtls_ecp_point_cmp( const mbedtls_ecp_point *P,
                            const mbedtls_ecp_point *Q );
 
 /**
- * \brief           Import a non-zero point from two ASCII strings
+ * \brief           This function imports a non-zero point from two ASCII
+ *                  strings.
  *
- * \param P         Destination point
- * \param radix     Input numeric base
- * \param x         First affine coordinate as a null-terminated string
- * \param y         Second affine coordinate as a null-terminated string
+ * \param P         The destination point.
+ * \param radix     The numeric base of the input.
+ * \param x         The first affine coordinate, as a null-terminated string.
+ * \param y         The second affine coordinate, as a null-terminated string.
  *
- * \return          0 if successful, or a MBEDTLS_ERR_MPI_XXX error code
+ * \return          \c 0 on success.
+ * \return          An \c MBEDTLS_ERR_MPI_XXX error code on failure.
  */
 int mbedtls_ecp_point_read_string( mbedtls_ecp_point *P, int radix,
                            const char *x, const char *y );
 
 /**
- * \brief           Export a point into unsigned binary data
+ * \brief           This function exports a point into unsigned binary data.
  *
- * \param grp       Group to which the point should belong
- * \param P         Point to export
- * \param format    Point format, should be a MBEDTLS_ECP_PF_XXX macro
- * \param olen      Length of the actual output
- * \param buf       Output buffer
- * \param buflen    Length of the output buffer
+ * \param grp       The group to which the point should belong.
+ * \param P         The point to export.
+ * \param format    The point format. Should be an \c MBEDTLS_ECP_PF_XXX macro.
+ * \param olen      The length of the output.
+ * \param buf       The output buffer.
+ * \param buflen    The length of the output buffer.
  *
- * \return          0 if successful,
- *                  or MBEDTLS_ERR_ECP_BAD_INPUT_DATA
- *                  or MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_ECP_BAD_INPUT_DATA
+ *                  or #MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL on failure.
  */
 int mbedtls_ecp_point_write_binary( const mbedtls_ecp_group *grp, const mbedtls_ecp_point *P,
                             int format, size_t *olen,
                             unsigned char *buf, size_t buflen );
 
 /**
- * \brief           Import a point from unsigned binary data
+ * \brief           This function imports a point from unsigned binary data.
  *
- * \param grp       Group to which the point should belong
- * \param P         Point to import
- * \param buf       Input buffer
- * \param ilen      Actual length of input
+ * \note            This function does not check that the point actually
+ *                  belongs to the given group, see mbedtls_ecp_check_pubkey()
+ *                  for that.
  *
- * \return          0 if successful,
- *                  MBEDTLS_ERR_ECP_BAD_INPUT_DATA if input is invalid,
- *                  MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed,
- *                  MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE if the point format
+ * \param grp       The group to which the point should belong.
+ * \param P         The point to import.
+ * \param buf       The input buffer.
+ * \param ilen      The length of the input.
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if input is invalid.
+ * \return          #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
+ * \return          #MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE if the point format
  *                  is not implemented.
  *
- * \note            This function does NOT check that the point actually
- *                  belongs to the given group, see mbedtls_ecp_check_pubkey() for
- *                  that.
  */
 int mbedtls_ecp_point_read_binary( const mbedtls_ecp_group *grp, mbedtls_ecp_point *P,
                            const unsigned char *buf, size_t ilen );
 
 /**
- * \brief           Import a point from a TLS ECPoint record
+ * \brief           This function imports a point from a TLS ECPoint record.
  *
- * \param grp       ECP group used
- * \param pt        Destination point
- * \param buf       $(Start of input buffer)
- * \param len       Buffer length
+ * \note            On function return, \p buf is updated to point to immediately
+ *                  after the ECPoint record.
  *
- * \note            buf is updated to point right after the ECPoint on exit
+ * \param grp       The ECP group used.
+ * \param pt        The destination point.
+ * \param buf       The address of the pointer to the start of the input buffer.
+ * \param len       The length of the buffer.
  *
- * \return          0 if successful,
- *                  MBEDTLS_ERR_MPI_XXX if initialization failed
- *                  MBEDTLS_ERR_ECP_BAD_INPUT_DATA if input is invalid
+ * \return          \c 0 on success.
+ * \return          An \c MBEDTLS_ERR_MPI_XXX error code on initialization failure.
+ * \return          #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if input is invalid.
  */
 int mbedtls_ecp_tls_read_point( const mbedtls_ecp_group *grp, mbedtls_ecp_point *pt,
                         const unsigned char **buf, size_t len );
 
 /**
- * \brief           Export a point as a TLS ECPoint record
+ * \brief           This function exports a point as a TLS ECPoint record.
  *
- * \param grp       ECP group used
- * \param pt        Point to export
- * \param format    Export format
- * \param olen      length of data written
- * \param buf       Buffer to write to
- * \param blen      Buffer length
+ * \param grp       The ECP group used.
+ * \param pt        The point format to export to. The point format is an
+ *                  \c MBEDTLS_ECP_PF_XXX constant.
+ * \param format    The export format.
+ * \param olen      The length of the data written.
+ * \param buf       The buffer to write to.
+ * \param blen      The length of the buffer.
  *
- * \return          0 if successful,
- *                  or MBEDTLS_ERR_ECP_BAD_INPUT_DATA
- *                  or MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_ECP_BAD_INPUT_DATA or
+ *                  #MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL on failure.
  */
 int mbedtls_ecp_tls_write_point( const mbedtls_ecp_group *grp, const mbedtls_ecp_point *pt,
                          int format, size_t *olen,
                          unsigned char *buf, size_t blen );
 
 /**
- * \brief           Set a group using well-known domain parameters
+ * \brief           This function sets a group using standardized domain parameters.
  *
- * \param grp       Destination group
- * \param id        Index in the list of well-known domain parameters
+ * \note            The index should be a value of the NamedCurve enum,
+ *                  as defined in <em>RFC-4492: Elliptic Curve Cryptography
+ *                  (ECC) Cipher Suites for Transport Layer Security (TLS)</em>,
+ *                  usually in the form of an \c MBEDTLS_ECP_DP_XXX macro.
  *
- * \return          0 if successful,
- *                  MBEDTLS_ERR_MPI_XXX if initialization failed
- *                  MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE for unkownn groups
+ * \param grp       The destination group.
+ * \param id        The identifier of the domain parameter set to load.
  *
- * \note            Index should be a value of RFC 4492's enum NamedCurve,
- *                  usually in the form of a MBEDTLS_ECP_DP_XXX macro.
+ * \return          \c 0 on success,
+ * \return          An \c MBEDTLS_ERR_MPI_XXX error code on initialization failure.
+ * \return          #MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE for unkownn groups.
+
  */
 int mbedtls_ecp_group_load( mbedtls_ecp_group *grp, mbedtls_ecp_group_id id );
 
 /**
- * \brief           Set a group from a TLS ECParameters record
+ * \brief           This function sets a group from a TLS ECParameters record.
  *
- * \param grp       Destination group
- * \param buf       &(Start of input buffer)
- * \param len       Buffer length
+ * \note            \p buf is updated to point right after the ECParameters record
+ *                  on exit.
  *
- * \note            buf is updated to point right after ECParameters on exit
+ * \param grp       The destination group.
+ * \param buf       The address of the pointer to the start of the input buffer.
+ * \param len       The length of the buffer.
  *
- * \return          0 if successful,
- *                  MBEDTLS_ERR_MPI_XXX if initialization failed
- *                  MBEDTLS_ERR_ECP_BAD_INPUT_DATA if input is invalid
+ * \return          \c 0 on success.
+ * \return          An \c MBEDTLS_ERR_MPI_XXX error code on initialization failure.
+ * \return          #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if input is invalid.
  */
 int mbedtls_ecp_tls_read_group( mbedtls_ecp_group *grp, const unsigned char **buf, size_t len );
 
 /**
- * \brief           Write the TLS ECParameters record for a group
+ * \brief           This function writes the TLS ECParameters record for a group.
  *
- * \param grp       ECP group used
- * \param olen      Number of bytes actually written
- * \param buf       Buffer to write to
- * \param blen      Buffer length
+ * \param grp       The ECP group used.
+ * \param olen      The number of Bytes written.
+ * \param buf       The buffer to write to.
+ * \param blen      The length of the buffer.
  *
- * \return          0 if successful,
- *                  or MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL on failure.
  */
 int mbedtls_ecp_tls_write_group( const mbedtls_ecp_group *grp, size_t *olen,
                          unsigned char *buf, size_t blen );
 
 /**
- * \brief           Multiplication by an integer: R = m * P
- *                  (Not thread-safe to use same group in multiple threads)
+ * \brief           This function performs multiplication of a point by
+ *                  an integer: \p R = \p m * \p P.
  *
- * \note            In order to prevent timing attacks, this function
- *                  executes the exact same sequence of (base field)
- *                  operations for any valid m. It avoids any if-branch or
- *                  array index depending on the value of m.
+ *                  It is not thread-safe to use same group in multiple threads.
  *
- * \note            If f_rng is not NULL, it is used to randomize intermediate
- *                  results in order to prevent potential timing attacks
- *                  targeting these results. It is recommended to always
- *                  provide a non-NULL f_rng (the overhead is negligible).
+ * \note            To prevent timing attacks, this function
+ *                  executes the exact same sequence of base-field
+ *                  operations for any valid \p m. It avoids any if-branch or
+ *                  array index depending on the value of \p m.
  *
- * \param grp       ECP group
- * \param R         Destination point
- * \param m         Integer by which to multiply
- * \param P         Point to multiply
- * \param f_rng     RNG function (see notes)
- * \param p_rng     RNG parameter
+ * \note            If \p f_rng is not NULL, it is used to randomize
+ *                  intermediate results to prevent potential timing attacks
+ *                  targeting these results. We recommend always providing
+ *                  a non-NULL \p f_rng. The overhead is negligible.
  *
- * \return          0 if successful,
- *                  MBEDTLS_ERR_ECP_INVALID_KEY if m is not a valid privkey
- *                  or P is not a valid pubkey,
- *                  MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed
+ * \param grp       The ECP group.
+ * \param R         The destination point.
+ * \param m         The integer by which to multiply.
+ * \param P         The point to multiply.
+ * \param f_rng     The RNG function.
+ * \param p_rng     The RNG context.
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_ECP_INVALID_KEY if \p m is not a valid private
+ *                  key, or \p P is not a valid public key.
+ * \return          #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
  */
 int mbedtls_ecp_mul( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
              const mbedtls_mpi *m, const mbedtls_ecp_point *P,
              int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
 
 /**
- * \brief           Multiplication and addition of two points by integers:
- *                  R = m * P + n * Q
- *                  (Not thread-safe to use same group in multiple threads)
+ * \brief           This function performs multiplication of a point by
+ *                  an integer: \p R = \p m * \p P in a restartable way.
  *
- * \note            In contrast to mbedtls_ecp_mul(), this function does not guarantee
- *                  a constant execution flow and timing.
+ * \see             mbedtls_ecp_mul()
  *
- * \param grp       ECP group
- * \param R         Destination point
- * \param m         Integer by which to multiply P
- * \param P         Point to multiply by m
- * \param n         Integer by which to multiply Q
- * \param Q         Point to be multiplied by n
+ * \note            This function does the same as \c mbedtls_ecp_mul(), but
+ *                  it can return early and restart according to the limit set
+ *                  with \c mbedtls_ecp_set_max_ops() to reduce blocking.
  *
- * \return          0 if successful,
- *                  MBEDTLS_ERR_ECP_INVALID_KEY if m or n is not a valid privkey
- *                  or P or Q is not a valid pubkey,
- *                  MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed
+ * \param grp       The ECP group.
+ * \param R         The destination point.
+ * \param m         The integer by which to multiply.
+ * \param P         The point to multiply.
+ * \param f_rng     The RNG function.
+ * \param p_rng     The RNG context.
+ * \param rs_ctx    The restart context (NULL disables restart).
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_ECP_INVALID_KEY if \p m is not a valid private
+ *                  key, or \p P is not a valid public key.
+ * \return          #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
+ * \return          #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
+ *                  operations was reached: see \c mbedtls_ecp_set_max_ops().
+ */
+int mbedtls_ecp_mul_restartable( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
+             const mbedtls_mpi *m, const mbedtls_ecp_point *P,
+             int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
+             mbedtls_ecp_restart_ctx *rs_ctx );
+
+/**
+ * \brief           This function performs multiplication and addition of two
+ *                  points by integers: \p R = \p m * \p P + \p n * \p Q
+ *
+ *                  It is not thread-safe to use same group in multiple threads.
+ *
+ * \note            In contrast to mbedtls_ecp_mul(), this function does not
+ *                  guarantee a constant execution flow and timing.
+ *
+ * \param grp       The ECP group.
+ * \param R         The destination point.
+ * \param m         The integer by which to multiply \p P.
+ * \param P         The point to multiply by \p m.
+ * \param n         The integer by which to multiply \p Q.
+ * \param Q         The point to be multiplied by \p n.
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_ECP_INVALID_KEY if \p m or \p n are not
+ *                  valid private keys, or \p P or \p Q are not valid public
+ *                  keys.
+ * \return          #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
  */
 int mbedtls_ecp_muladd( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
              const mbedtls_mpi *m, const mbedtls_ecp_point *P,
              const mbedtls_mpi *n, const mbedtls_ecp_point *Q );
 
 /**
- * \brief           Check that a point is a valid public key on this curve
+ * \brief           This function performs multiplication and addition of two
+ *                  points by integers: \p R = \p m * \p P + \p n * \p Q in a
+ *                  restartable way.
  *
- * \param grp       Curve/group the point should belong to
- * \param pt        Point to check
+ * \see             \c mbedtls_ecp_muladd()
  *
- * \return          0 if point is a valid public key,
- *                  MBEDTLS_ERR_ECP_INVALID_KEY otherwise.
+ * \note            This function works the same as \c mbedtls_ecp_muladd(),
+ *                  but it can return early and restart according to the limit
+ *                  set with \c mbedtls_ecp_set_max_ops() to reduce blocking.
  *
- * \note            This function only checks the point is non-zero, has valid
- *                  coordinates and lies on the curve, but not that it is
- *                  indeed a multiple of G. This is additional check is more
- *                  expensive, isn't required by standards, and shouldn't be
- *                  necessary if the group used has a small cofactor. In
- *                  particular, it is useless for the NIST groups which all
- *                  have a cofactor of 1.
+ * \param grp       The ECP group.
+ * \param R         The destination point.
+ * \param m         The integer by which to multiply \p P.
+ * \param P         The point to multiply by \p m.
+ * \param n         The integer by which to multiply \p Q.
+ * \param Q         The point to be multiplied by \p n.
+ * \param rs_ctx    The restart context (NULL disables restart).
  *
- * \note            Uses bare components rather than an mbedtls_ecp_keypair structure
- *                  in order to ease use with other structures such as
- *                  mbedtls_ecdh_context of mbedtls_ecdsa_context.
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_ECP_INVALID_KEY if \p m or \p n are not
+ *                  valid private keys, or \p P or \p Q are not valid public
+ *                  keys.
+ * \return          #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
+ * \return          #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
+ *                  operations was reached: see \c mbedtls_ecp_set_max_ops().
+ */
+int mbedtls_ecp_muladd_restartable(
+             mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
+             const mbedtls_mpi *m, const mbedtls_ecp_point *P,
+             const mbedtls_mpi *n, const mbedtls_ecp_point *Q,
+             mbedtls_ecp_restart_ctx *rs_ctx );
+
+/**
+ * \brief           This function checks that a point is a valid public key
+ *                  on this curve.
+ *
+ *                  It only checks that the point is non-zero, has
+ *                  valid coordinates and lies on the curve. It does not verify
+ *                  that it is indeed a multiple of \p G. This additional
+ *                  check is computationally more expensive, is not required
+ *                  by standards, and should not be necessary if the group
+ *                  used has a small cofactor. In particular, it is useless for
+ *                  the NIST groups which all have a cofactor of 1.
+ *
+ * \note            This function uses bare components rather than an
+ *                  ::mbedtls_ecp_keypair structure, to ease use with other
+ *                  structures, such as ::mbedtls_ecdh_context or
+ *                  ::mbedtls_ecdsa_context.
+ *
+ * \param grp       The curve the point should lie on.
+ * \param pt        The point to check.
+ *
+ * \return          \c 0 if the point is a valid public key.
+ * \return          #MBEDTLS_ERR_ECP_INVALID_KEY on failure.
  */
 int mbedtls_ecp_check_pubkey( const mbedtls_ecp_group *grp, const mbedtls_ecp_point *pt );
 
 /**
- * \brief           Check that an mbedtls_mpi is a valid private key for this curve
+ * \brief           This function checks that an \p mbedtls_mpi is a valid private
+ *                  key for this curve.
  *
- * \param grp       Group used
- * \param d         Integer to check
+ * \note            This function uses bare components rather than an
+ *                  ::mbedtls_ecp_keypair structure to ease use with other
+ *                  structures, such as ::mbedtls_ecdh_context or
+ *                  ::mbedtls_ecdsa_context.
  *
- * \return          0 if point is a valid private key,
- *                  MBEDTLS_ERR_ECP_INVALID_KEY otherwise.
+ * \param grp       The group used.
+ * \param d         The integer to check.
  *
- * \note            Uses bare components rather than an mbedtls_ecp_keypair structure
- *                  in order to ease use with other structures such as
- *                  mbedtls_ecdh_context of mbedtls_ecdsa_context.
+ * \return          \c 0 if the point is a valid private key.
+ * \return          #MBEDTLS_ERR_ECP_INVALID_KEY on failure.
  */
 int mbedtls_ecp_check_privkey( const mbedtls_ecp_group *grp, const mbedtls_mpi *d );
 
 /**
- * \brief           Generate a keypair with configurable base point
+ * \brief           This function generates a private key.
  *
- * \param grp       ECP group
- * \param G         Chosen base point
- * \param d         Destination MPI (secret part)
- * \param Q         Destination point (public part)
- * \param f_rng     RNG function
- * \param p_rng     RNG parameter
+ * \param grp       The ECP group.
+ * \param d         The destination MPI (secret part).
+ * \param f_rng     The RNG function.
+ * \param p_rng     The RNG parameter.
  *
- * \return          0 if successful,
- *                  or a MBEDTLS_ERR_ECP_XXX or MBEDTLS_MPI_XXX error code
+ * \return          \c 0 on success.
+ * \return          An \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_MPI_XXX error code
+ *                  on failure.
+ */
+int mbedtls_ecp_gen_privkey( const mbedtls_ecp_group *grp,
+                     mbedtls_mpi *d,
+                     int (*f_rng)(void *, unsigned char *, size_t),
+                     void *p_rng );
+
+/**
+ * \brief           This function generates a keypair with a configurable base
+ *                  point.
  *
- * \note            Uses bare components rather than an mbedtls_ecp_keypair structure
- *                  in order to ease use with other structures such as
- *                  mbedtls_ecdh_context of mbedtls_ecdsa_context.
+ * \note            This function uses bare components rather than an
+ *                  ::mbedtls_ecp_keypair structure to ease use with other
+ *                  structures, such as ::mbedtls_ecdh_context or
+ *                  ::mbedtls_ecdsa_context.
+ *
+ * \param grp       The ECP group.
+ * \param G         The chosen base point.
+ * \param d         The destination MPI (secret part).
+ * \param Q         The destination point (public part).
+ * \param f_rng     The RNG function.
+ * \param p_rng     The RNG context.
+ *
+ * \return          \c 0 on success.
+ * \return          An \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_MPI_XXX error code
+ *                  on failure.
  */
 int mbedtls_ecp_gen_keypair_base( mbedtls_ecp_group *grp,
                      const mbedtls_ecp_point *G,
@@ -617,57 +921,66 @@
                      void *p_rng );
 
 /**
- * \brief           Generate a keypair
+ * \brief           This function generates an ECP keypair.
  *
- * \param grp       ECP group
- * \param d         Destination MPI (secret part)
- * \param Q         Destination point (public part)
- * \param f_rng     RNG function
- * \param p_rng     RNG parameter
+ * \note            This function uses bare components rather than an
+ *                  ::mbedtls_ecp_keypair structure to ease use with other
+ *                  structures, such as ::mbedtls_ecdh_context or
+ *                  ::mbedtls_ecdsa_context.
  *
- * \return          0 if successful,
- *                  or a MBEDTLS_ERR_ECP_XXX or MBEDTLS_MPI_XXX error code
+ * \param grp       The ECP group.
+ * \param d         The destination MPI (secret part).
+ * \param Q         The destination point (public part).
+ * \param f_rng     The RNG function.
+ * \param p_rng     The RNG context.
  *
- * \note            Uses bare components rather than an mbedtls_ecp_keypair structure
- *                  in order to ease use with other structures such as
- *                  mbedtls_ecdh_context of mbedtls_ecdsa_context.
+ * \return          \c 0 on success.
+ * \return          An \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_MPI_XXX error code
+ *                  on failure.
  */
 int mbedtls_ecp_gen_keypair( mbedtls_ecp_group *grp, mbedtls_mpi *d, mbedtls_ecp_point *Q,
                      int (*f_rng)(void *, unsigned char *, size_t),
                      void *p_rng );
 
 /**
- * \brief           Generate a keypair
+ * \brief           This function generates an ECP key.
  *
- * \param grp_id    ECP group identifier
- * \param key       Destination keypair
- * \param f_rng     RNG function
- * \param p_rng     RNG parameter
+ * \param grp_id    The ECP group identifier.
+ * \param key       The destination key.
+ * \param f_rng     The RNG function.
+ * \param p_rng     The RNG context.
  *
- * \return          0 if successful,
- *                  or a MBEDTLS_ERR_ECP_XXX or MBEDTLS_MPI_XXX error code
+ * \return          \c 0 on success.
+ * \return          An \c MBEDTLS_ERR_ECP_XXX or \c MBEDTLS_MPI_XXX error code
+ *                  on failure.
  */
 int mbedtls_ecp_gen_key( mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
                 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
 
 /**
- * \brief           Check a public-private key pair
+ * \brief           This function checks that the keypair objects
+ *                  \p pub and \p prv have the same group and the
+ *                  same public point, and that the private key in
+ *                  \p prv is consistent with the public key.
  *
- * \param pub       Keypair structure holding a public key
- * \param prv       Keypair structure holding a private (plus public) key
+ * \param pub       The keypair structure holding the public key.
+ *                  If it contains a private key, that part is ignored.
+ * \param prv       The keypair structure holding the full keypair.
  *
- * \return          0 if successful (keys are valid and match), or
- *                  MBEDTLS_ERR_ECP_BAD_INPUT_DATA, or
- *                  a MBEDTLS_ERR_ECP_XXX or MBEDTLS_ERR_MPI_XXX code.
+ * \return          \c 0 on success, meaning that the keys are valid and match.
+ * \return          #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if the keys are invalid or do not match.
+ * \return          An \c MBEDTLS_ERR_ECP_XXX or an \c MBEDTLS_ERR_MPI_XXX
+ *                  error code on calculation failure.
  */
 int mbedtls_ecp_check_pub_priv( const mbedtls_ecp_keypair *pub, const mbedtls_ecp_keypair *prv );
 
 #if defined(MBEDTLS_SELF_TEST)
 
 /**
- * \brief          Checkup routine
+ * \brief          The ECP checkup routine.
  *
- * \return         0 if successful, or 1 if a test failed
+ * \return         \c 0 on success.
+ * \return         \c 1 on failure.
  */
 int mbedtls_ecp_self_test( int verbose );
 
@@ -677,8 +990,4 @@
 }
 #endif
 
-#else  /* MBEDTLS_ECP_ALT */
-#include "ecp_alt.h"
-#endif /* MBEDTLS_ECP_ALT */
-
 #endif /* ecp.h */
diff --git a/ext/mbedtls/include/mbedtls/md.h b/ext/mbedtls/include/mbedtls/md.h
index 9b996a9..8bcf766 100644
--- a/ext/mbedtls/include/mbedtls/md.h
+++ b/ext/mbedtls/include/mbedtls/md.h
@@ -1,11 +1,12 @@
-/**
+ /**
  * \file md.h
  *
- * \brief Generic message digest wrapper
+ * \brief This file contains the generic message-digest wrapper.
  *
  * \author Adriaan de Jong <dejong@fox-it.com>
- *
- *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ */
+/*
+ *  Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved
  *  SPDX-License-Identifier: Apache-2.0
  *
  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
@@ -20,33 +21,51 @@
  *  See the License for the specific language governing permissions and
  *  limitations under the License.
  *
- *  This file is part of mbed TLS (https://tls.mbed.org)
+ *  This file is part of Mbed TLS (https://tls.mbed.org)
  */
+
 #ifndef MBEDTLS_MD_H
 #define MBEDTLS_MD_H
 
 #include <stddef.h>
 
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
 #define MBEDTLS_ERR_MD_FEATURE_UNAVAILABLE                -0x5080  /**< The selected feature is not available. */
 #define MBEDTLS_ERR_MD_BAD_INPUT_DATA                     -0x5100  /**< Bad input parameters to function. */
 #define MBEDTLS_ERR_MD_ALLOC_FAILED                       -0x5180  /**< Failed to allocate memory. */
 #define MBEDTLS_ERR_MD_FILE_IO_ERROR                      -0x5200  /**< Opening or reading of file failed. */
 
+/* MBEDTLS_ERR_MD_HW_ACCEL_FAILED is deprecated and should not be used. */
+#define MBEDTLS_ERR_MD_HW_ACCEL_FAILED                    -0x5280  /**< MD hardware accelerator failed. */
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+/**
+ * \brief     Supported message digests.
+ *
+ * \warning   MD2, MD4, MD5 and SHA-1 are considered weak message digests and
+ *            their use constitutes a security risk. We recommend considering
+ *            stronger message digests instead.
+ *
+ */
 typedef enum {
-    MBEDTLS_MD_NONE=0,
-    MBEDTLS_MD_MD2,
-    MBEDTLS_MD_MD4,
-    MBEDTLS_MD_MD5,
-    MBEDTLS_MD_SHA1,
-    MBEDTLS_MD_SHA224,
-    MBEDTLS_MD_SHA256,
-    MBEDTLS_MD_SHA384,
-    MBEDTLS_MD_SHA512,
-    MBEDTLS_MD_RIPEMD160,
+    MBEDTLS_MD_NONE=0,    /**< None. */
+    MBEDTLS_MD_MD2,       /**< The MD2 message digest. */
+    MBEDTLS_MD_MD4,       /**< The MD4 message digest. */
+    MBEDTLS_MD_MD5,       /**< The MD5 message digest. */
+    MBEDTLS_MD_SHA1,      /**< The SHA-1 message digest. */
+    MBEDTLS_MD_SHA224,    /**< The SHA-224 message digest. */
+    MBEDTLS_MD_SHA256,    /**< The SHA-256 message digest. */
+    MBEDTLS_MD_SHA384,    /**< The SHA-384 message digest. */
+    MBEDTLS_MD_SHA512,    /**< The SHA-512 message digest. */
+    MBEDTLS_MD_RIPEMD160, /**< The RIPEMD-160 message digest. */
 } mbedtls_md_type_t;
 
 #if defined(MBEDTLS_SHA512_C)
@@ -56,65 +75,80 @@
 #endif
 
 /**
- * Opaque struct defined in md_internal.h
+ * Opaque struct defined in md_internal.h.
  */
 typedef struct mbedtls_md_info_t mbedtls_md_info_t;
 
 /**
- * Generic message digest context.
+ * The generic message-digest context.
  */
-typedef struct {
-    /** Information about the associated message digest */
+typedef struct mbedtls_md_context_t
+{
+    /** Information about the associated message digest. */
     const mbedtls_md_info_t *md_info;
 
-    /** Digest-specific context */
+    /** The digest-specific context. */
     void *md_ctx;
 
-    /** HMAC part of the context */
+    /** The HMAC part of the context. */
     void *hmac_ctx;
 } mbedtls_md_context_t;
 
 /**
- * \brief Returns the list of digests supported by the generic digest module.
+ * \brief           This function returns the list of digests supported by the
+ *                  generic digest module.
  *
- * \return          a statically allocated array of digests, the last entry
- *                  is 0.
+ * \return          A statically allocated array of digests. Each element
+ *                  in the returned list is an integer belonging to the
+ *                  message-digest enumeration #mbedtls_md_type_t.
+ *                  The last entry is 0.
  */
 const int *mbedtls_md_list( void );
 
 /**
- * \brief           Returns the message digest information associated with the
- *                  given digest name.
+ * \brief           This function returns the message-digest information
+ *                  associated with the given digest name.
  *
- * \param md_name   Name of the digest to search for.
+ * \param md_name   The name of the digest to search for.
  *
- * \return          The message digest information associated with md_name or
- *                  NULL if not found.
+ * \return          The message-digest information associated with \p md_name.
+ * \return          NULL if the associated message-digest information is not found.
  */
 const mbedtls_md_info_t *mbedtls_md_info_from_string( const char *md_name );
 
 /**
- * \brief           Returns the message digest information associated with the
- *                  given digest type.
+ * \brief           This function returns the message-digest information
+ *                  associated with the given digest type.
  *
- * \param md_type   type of digest to search for.
+ * \param md_type   The type of digest to search for.
  *
- * \return          The message digest information associated with md_type or
- *                  NULL if not found.
+ * \return          The message-digest information associated with \p md_type.
+ * \return          NULL if the associated message-digest information is not found.
  */
 const mbedtls_md_info_t *mbedtls_md_info_from_type( mbedtls_md_type_t md_type );
 
 /**
- * \brief           Initialize a md_context (as NONE)
- *                  This should always be called first.
- *                  Prepares the context for mbedtls_md_setup() or mbedtls_md_free().
+ * \brief           This function initializes a message-digest context without
+ *                  binding it to a particular message-digest algorithm.
+ *
+ *                  This function should always be called first. It prepares the
+ *                  context for mbedtls_md_setup() for binding it to a
+ *                  message-digest algorithm.
  */
 void mbedtls_md_init( mbedtls_md_context_t *ctx );
 
 /**
- * \brief           Free and clear the internal structures of ctx.
- *                  Can be called at any time after mbedtls_md_init().
- *                  Mandatory once mbedtls_md_setup() has been called.
+ * \brief           This function clears the internal structure of \p ctx and
+ *                  frees any embedded internal structure, but does not free
+ *                  \p ctx itself.
+ *
+ *                  If you have called mbedtls_md_setup() on \p ctx, you must
+ *                  call mbedtls_md_free() when you are no longer using the
+ *                  context.
+ *                  Calling this function if you have previously
+ *                  called mbedtls_md_init() and nothing else is optional.
+ *                  You must not call this function if you have not called
+ *                  mbedtls_md_init().
  */
 void mbedtls_md_free( mbedtls_md_context_t *ctx );
 
@@ -125,220 +159,300 @@
 #define MBEDTLS_DEPRECATED
 #endif
 /**
- * \brief           Select MD to use and allocate internal structures.
- *                  Should be called after mbedtls_md_init() or mbedtls_md_free().
+ * \brief           This function selects the message digest algorithm to use,
+ *                  and allocates internal structures.
+ *
+ *                  It should be called after mbedtls_md_init() or mbedtls_md_free().
  *                  Makes it necessary to call mbedtls_md_free() later.
  *
  * \deprecated      Superseded by mbedtls_md_setup() in 2.0.0
  *
- * \param ctx       Context to set up.
- * \param md_info   Message digest to use.
+ * \param ctx       The context to set up.
+ * \param md_info   The information structure of the message-digest algorithm
+ *                  to use.
  *
- * \returns         \c 0 on success,
- *                  \c MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter failure,
- *                  \c MBEDTLS_ERR_MD_ALLOC_FAILED memory allocation failure.
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
+ *                  failure.
+ * \return          #MBEDTLS_ERR_MD_ALLOC_FAILED on memory-allocation failure.
  */
 int mbedtls_md_init_ctx( mbedtls_md_context_t *ctx, const mbedtls_md_info_t *md_info ) MBEDTLS_DEPRECATED;
 #undef MBEDTLS_DEPRECATED
 #endif /* MBEDTLS_DEPRECATED_REMOVED */
 
 /**
- * \brief           Select MD to use and allocate internal structures.
- *                  Should be called after mbedtls_md_init() or mbedtls_md_free().
- *                  Makes it necessary to call mbedtls_md_free() later.
+ * \brief           This function selects the message digest algorithm to use,
+ *                  and allocates internal structures.
  *
- * \param ctx       Context to set up.
- * \param md_info   Message digest to use.
- * \param hmac      0 to save some memory if HMAC will not be used,
- *                  non-zero is HMAC is going to be used with this context.
+ *                  It should be called after mbedtls_md_init() or
+ *                  mbedtls_md_free(). Makes it necessary to call
+ *                  mbedtls_md_free() later.
  *
- * \returns         \c 0 on success,
- *                  \c MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter failure,
- *                  \c MBEDTLS_ERR_MD_ALLOC_FAILED memory allocation failure.
+ * \param ctx       The context to set up.
+ * \param md_info   The information structure of the message-digest algorithm
+ *                  to use.
+ * \param hmac      Defines if HMAC is used. 0: HMAC is not used (saves some memory),
+ *                  or non-zero: HMAC is used with this context.
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
+ *                  failure.
+ * \return          #MBEDTLS_ERR_MD_ALLOC_FAILED on memory-allocation failure.
  */
 int mbedtls_md_setup( mbedtls_md_context_t *ctx, const mbedtls_md_info_t *md_info, int hmac );
 
 /**
- * \brief           Clone the state of an MD context
+ * \brief           This function clones the state of an message-digest
+ *                  context.
  *
- * \note            The two contexts must have been setup to the same type
- *                  (cloning from SHA-256 to SHA-512 make no sense).
+ * \note            You must call mbedtls_md_setup() on \c dst before calling
+ *                  this function.
  *
- * \warning         Only clones the MD state, not the HMAC state! (for now)
+ * \note            The two contexts must have the same type,
+ *                  for example, both are SHA-256.
  *
- * \param dst       The destination context
- * \param src       The context to be cloned
+ * \warning         This function clones the message-digest state, not the
+ *                  HMAC state.
  *
- * \return          \c 0 on success,
- *                  \c MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter failure.
+ * \param dst       The destination context.
+ * \param src       The context to be cloned.
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification failure.
  */
 int mbedtls_md_clone( mbedtls_md_context_t *dst,
                       const mbedtls_md_context_t *src );
 
 /**
- * \brief           Returns the size of the message digest output.
+ * \brief           This function extracts the message-digest size from the
+ *                  message-digest information structure.
  *
- * \param md_info   message digest info
+ * \param md_info   The information structure of the message-digest algorithm
+ *                  to use.
  *
- * \return          size of the message digest output in bytes.
+ * \return          The size of the message-digest output in Bytes.
  */
 unsigned char mbedtls_md_get_size( const mbedtls_md_info_t *md_info );
 
 /**
- * \brief           Returns the type of the message digest output.
+ * \brief           This function extracts the message-digest type from the
+ *                  message-digest information structure.
  *
- * \param md_info   message digest info
+ * \param md_info   The information structure of the message-digest algorithm
+ *                  to use.
  *
- * \return          type of the message digest output.
+ * \return          The type of the message digest.
  */
 mbedtls_md_type_t mbedtls_md_get_type( const mbedtls_md_info_t *md_info );
 
 /**
- * \brief           Returns the name of the message digest output.
+ * \brief           This function extracts the message-digest name from the
+ *                  message-digest information structure.
  *
- * \param md_info   message digest info
+ * \param md_info   The information structure of the message-digest algorithm
+ *                  to use.
  *
- * \return          name of the message digest output.
+ * \return          The name of the message digest.
  */
 const char *mbedtls_md_get_name( const mbedtls_md_info_t *md_info );
 
 /**
- * \brief           Prepare the context to digest a new message.
- *                  Generally called after mbedtls_md_setup() or mbedtls_md_finish().
- *                  Followed by mbedtls_md_update().
+ * \brief           This function starts a message-digest computation.
  *
- * \param ctx       generic message digest context.
+ *                  You must call this function after setting up the context
+ *                  with mbedtls_md_setup(), and before passing data with
+ *                  mbedtls_md_update().
  *
- * \returns         0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
- *                  verification fails.
+ * \param ctx       The generic message-digest context.
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
+ *                  failure.
  */
 int mbedtls_md_starts( mbedtls_md_context_t *ctx );
 
 /**
- * \brief           Generic message digest process buffer
- *                  Called between mbedtls_md_starts() and mbedtls_md_finish().
- *                  May be called repeatedly.
+ * \brief           This function feeds an input buffer into an ongoing
+ *                  message-digest computation.
  *
- * \param ctx       Generic message digest context
- * \param input     buffer holding the  datal
- * \param ilen      length of the input data
+ *                  You must call mbedtls_md_starts() before calling this
+ *                  function. You may call this function multiple times.
+ *                  Afterwards, call mbedtls_md_finish().
  *
- * \returns         0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
- *                  verification fails.
+ * \param ctx       The generic message-digest context.
+ * \param input     The buffer holding the input data.
+ * \param ilen      The length of the input data.
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
+ *                  failure.
  */
 int mbedtls_md_update( mbedtls_md_context_t *ctx, const unsigned char *input, size_t ilen );
 
 /**
- * \brief           Generic message digest final digest
- *                  Called after mbedtls_md_update().
- *                  Usually followed by mbedtls_md_free() or mbedtls_md_starts().
+ * \brief           This function finishes the digest operation,
+ *                  and writes the result to the output buffer.
  *
- * \param ctx       Generic message digest context
- * \param output    Generic message digest checksum result
+ *                  Call this function after a call to mbedtls_md_starts(),
+ *                  followed by any number of calls to mbedtls_md_update().
+ *                  Afterwards, you may either clear the context with
+ *                  mbedtls_md_free(), or call mbedtls_md_starts() to reuse
+ *                  the context for another digest operation with the same
+ *                  algorithm.
  *
- * \returns         0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
- *                  verification fails.
+ * \param ctx       The generic message-digest context.
+ * \param output    The buffer for the generic message-digest checksum result.
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
+ *                  failure.
  */
 int mbedtls_md_finish( mbedtls_md_context_t *ctx, unsigned char *output );
 
 /**
- * \brief          Output = message_digest( input buffer )
+ * \brief          This function calculates the message-digest of a buffer,
+ *                 with respect to a configurable message-digest algorithm
+ *                 in a single call.
  *
- * \param md_info  message digest info
- * \param input    buffer holding the  data
- * \param ilen     length of the input data
- * \param output   Generic message digest checksum result
+ *                 The result is calculated as
+ *                 Output = message_digest(input buffer).
  *
- * \returns        0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
- *                 verification fails.
+ * \param md_info  The information structure of the message-digest algorithm
+ *                 to use.
+ * \param input    The buffer holding the data.
+ * \param ilen     The length of the input data.
+ * \param output   The generic message-digest checksum result.
+ *
+ * \return         \c 0 on success.
+ * \return         #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
+ *                 failure.
  */
 int mbedtls_md( const mbedtls_md_info_t *md_info, const unsigned char *input, size_t ilen,
         unsigned char *output );
 
 #if defined(MBEDTLS_FS_IO)
 /**
- * \brief          Output = message_digest( file contents )
+ * \brief          This function calculates the message-digest checksum
+ *                 result of the contents of the provided file.
  *
- * \param md_info  message digest info
- * \param path     input file name
- * \param output   generic message digest checksum result
+ *                 The result is calculated as
+ *                 Output = message_digest(file contents).
  *
- * \return         0 if successful,
- *                 MBEDTLS_ERR_MD_FILE_IO_ERROR if file input failed,
- *                 MBEDTLS_ERR_MD_BAD_INPUT_DATA if md_info was NULL.
+ * \param md_info  The information structure of the message-digest algorithm
+ *                 to use.
+ * \param path     The input file name.
+ * \param output   The generic message-digest checksum result.
+ *
+ * \return         \c 0 on success.
+ * \return         #MBEDTLS_ERR_MD_FILE_IO_ERROR on an I/O error accessing
+ *                 the file pointed by \p path.
+ * \return         #MBEDTLS_ERR_MD_BAD_INPUT_DATA if \p md_info was NULL.
  */
 int mbedtls_md_file( const mbedtls_md_info_t *md_info, const char *path,
                      unsigned char *output );
 #endif /* MBEDTLS_FS_IO */
 
 /**
- * \brief           Set HMAC key and prepare to authenticate a new message.
- *                  Usually called after mbedtls_md_setup() or mbedtls_md_hmac_finish().
+ * \brief           This function sets the HMAC key and prepares to
+ *                  authenticate a new message.
  *
- * \param ctx       HMAC context
- * \param key       HMAC secret key
- * \param keylen    length of the HMAC key in bytes
+ *                  Call this function after mbedtls_md_setup(), to use
+ *                  the MD context for an HMAC calculation, then call
+ *                  mbedtls_md_hmac_update() to provide the input data, and
+ *                  mbedtls_md_hmac_finish() to get the HMAC value.
  *
- * \returns         0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
- *                  verification fails.
+ * \param ctx       The message digest context containing an embedded HMAC
+ *                  context.
+ * \param key       The HMAC secret key.
+ * \param keylen    The length of the HMAC key in Bytes.
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
+ *                  failure.
  */
 int mbedtls_md_hmac_starts( mbedtls_md_context_t *ctx, const unsigned char *key,
                     size_t keylen );
 
 /**
- * \brief           Generic HMAC process buffer.
- *                  Called between mbedtls_md_hmac_starts() or mbedtls_md_hmac_reset()
- *                  and mbedtls_md_hmac_finish().
- *                  May be called repeatedly.
+ * \brief           This function feeds an input buffer into an ongoing HMAC
+ *                  computation.
  *
- * \param ctx       HMAC context
- * \param input     buffer holding the  data
- * \param ilen      length of the input data
+ *                  Call mbedtls_md_hmac_starts() or mbedtls_md_hmac_reset()
+ *                  before calling this function.
+ *                  You may call this function multiple times to pass the
+ *                  input piecewise.
+ *                  Afterwards, call mbedtls_md_hmac_finish().
  *
- * \returns         0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
- *                  verification fails.
+ * \param ctx       The message digest context containing an embedded HMAC
+ *                  context.
+ * \param input     The buffer holding the input data.
+ * \param ilen      The length of the input data.
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
+ *                  failure.
  */
 int mbedtls_md_hmac_update( mbedtls_md_context_t *ctx, const unsigned char *input,
                     size_t ilen );
 
 /**
- * \brief           Output HMAC.
- *                  Called after mbedtls_md_hmac_update().
- *                  Usually followed by mbedtls_md_hmac_reset(),
- *                  mbedtls_md_hmac_starts(), or mbedtls_md_free().
+ * \brief           This function finishes the HMAC operation, and writes
+ *                  the result to the output buffer.
  *
- * \param ctx       HMAC context
- * \param output    Generic HMAC checksum result
+ *                  Call this function after mbedtls_md_hmac_starts() and
+ *                  mbedtls_md_hmac_update() to get the HMAC value. Afterwards
+ *                  you may either call mbedtls_md_free() to clear the context,
+ *                  or call mbedtls_md_hmac_reset() to reuse the context with
+ *                  the same HMAC key.
  *
- * \returns         0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
- *                  verification fails.
+ * \param ctx       The message digest context containing an embedded HMAC
+ *                  context.
+ * \param output    The generic HMAC checksum result.
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
+ *                  failure.
  */
 int mbedtls_md_hmac_finish( mbedtls_md_context_t *ctx, unsigned char *output);
 
 /**
- * \brief           Prepare to authenticate a new message with the same key.
- *                  Called after mbedtls_md_hmac_finish() and before
- *                  mbedtls_md_hmac_update().
+ * \brief           This function prepares to authenticate a new message with
+ *                  the same key as the previous HMAC operation.
  *
- * \param ctx       HMAC context to be reset
+ *                  You may call this function after mbedtls_md_hmac_finish().
+ *                  Afterwards call mbedtls_md_hmac_update() to pass the new
+ *                  input.
  *
- * \returns         0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
- *                  verification fails.
+ * \param ctx       The message digest context containing an embedded HMAC
+ *                  context.
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
+ *                  failure.
  */
 int mbedtls_md_hmac_reset( mbedtls_md_context_t *ctx );
 
 /**
- * \brief          Output = Generic_HMAC( hmac key, input buffer )
+ * \brief          This function calculates the full generic HMAC
+ *                 on the input buffer with the provided key.
  *
- * \param md_info  message digest info
- * \param key      HMAC secret key
- * \param keylen   length of the HMAC key in bytes
- * \param input    buffer holding the  data
- * \param ilen     length of the input data
- * \param output   Generic HMAC-result
+ *                 The function allocates the context, performs the
+ *                 calculation, and frees the context.
  *
- * \returns        0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
- *                 verification fails.
+ *                 The HMAC result is calculated as
+ *                 output = generic HMAC(hmac key, input buffer).
+ *
+ * \param md_info  The information structure of the message-digest algorithm
+ *                 to use.
+ * \param key      The HMAC secret key.
+ * \param keylen   The length of the HMAC secret key in Bytes.
+ * \param input    The buffer holding the input data.
+ * \param ilen     The length of the input data.
+ * \param output   The generic HMAC result.
+ *
+ * \return         \c 0 on success.
+ * \return         #MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter-verification
+ *                 failure.
  */
 int mbedtls_md_hmac( const mbedtls_md_info_t *md_info, const unsigned char *key, size_t keylen,
                 const unsigned char *input, size_t ilen,
diff --git a/ext/mbedtls/include/mbedtls/pk.h b/ext/mbedtls/include/mbedtls/pk.h
index f9f9b9b..df3a03c 100644
--- a/ext/mbedtls/include/mbedtls/pk.h
+++ b/ext/mbedtls/include/mbedtls/pk.h
@@ -2,7 +2,8 @@
  * \file pk.h
  *
  * \brief Public Key abstraction layer
- *
+ */
+/*
  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
  *  SPDX-License-Identifier: Apache-2.0
  *
@@ -62,7 +63,10 @@
 #define MBEDTLS_ERR_PK_INVALID_ALG         -0x3A80  /**< The algorithm tag or value is invalid. */
 #define MBEDTLS_ERR_PK_UNKNOWN_NAMED_CURVE -0x3A00  /**< Elliptic curve is unsupported (only NIST curves are supported). */
 #define MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE -0x3980  /**< Unavailable feature, e.g. RSA disabled for RSA key. */
-#define MBEDTLS_ERR_PK_SIG_LEN_MISMATCH    -0x3900  /**< The signature is valid but its length is less than expected. */
+#define MBEDTLS_ERR_PK_SIG_LEN_MISMATCH    -0x3900  /**< The buffer contains a valid signature followed by more data. */
+
+/* MBEDTLS_ERR_PK_HW_ACCEL_FAILED is deprecated and should not be used. */
+#define MBEDTLS_ERR_PK_HW_ACCEL_FAILED     -0x3880  /**< PK hardware accelerator failed. */
 
 #ifdef __cplusplus
 extern "C" {
@@ -85,7 +89,7 @@
  * \brief           Options for RSASSA-PSS signature verification.
  *                  See \c mbedtls_rsa_rsassa_pss_verify_ext()
  */
-typedef struct
+typedef struct mbedtls_pk_rsassa_pss_options
 {
     mbedtls_md_type_t mgf1_hash_id;
     int expected_salt_len;
@@ -105,7 +109,7 @@
 /**
  * \brief           Item to send to the debug module
  */
-typedef struct
+typedef struct mbedtls_pk_debug_item
 {
     mbedtls_pk_debug_type type;
     const char *name;
@@ -123,12 +127,26 @@
 /**
  * \brief           Public key container
  */
-typedef struct
+typedef struct mbedtls_pk_context
 {
-    const mbedtls_pk_info_t *   pk_info; /**< Public key informations        */
+    const mbedtls_pk_info_t *   pk_info; /**< Public key information         */
     void *                      pk_ctx;  /**< Underlying public key context  */
 } mbedtls_pk_context;
 
+#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
+/**
+ * \brief           Context for resuming operations
+ */
+typedef struct
+{
+    const mbedtls_pk_info_t *   pk_info; /**< Public key information         */
+    void *                      rs_ctx;  /**< Underlying restart context     */
+} mbedtls_pk_restart_ctx;
+#else /* MBEDTLS_ECDSA_C && MBEDTLS_ECP_RESTARTABLE */
+/* Now we can declare functions that take a pointer to that */
+typedef void mbedtls_pk_restart_ctx;
+#endif /* MBEDTLS_ECDSA_C && MBEDTLS_ECP_RESTARTABLE */
+
 #if defined(MBEDTLS_RSA_C)
 /**
  * Quick access to an RSA context inside a PK context.
@@ -188,6 +206,18 @@
  */
 void mbedtls_pk_free( mbedtls_pk_context *ctx );
 
+#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
+/**
+ * \brief           Initialize a restart context
+ */
+void mbedtls_pk_restart_init( mbedtls_pk_restart_ctx *ctx );
+
+/**
+ * \brief           Free the components of a restart context
+ */
+void mbedtls_pk_restart_free( mbedtls_pk_restart_ctx *ctx );
+#endif /* MBEDTLS_ECDSA_C && MBEDTLS_ECP_RESTARTABLE */
+
 /**
  * \brief           Initialize a PK context with the information given
  *                  and allocates the type-specific PK subcontext.
@@ -267,8 +297,8 @@
  * \param sig_len   Signature length
  *
  * \return          0 on success (signature is valid),
- *                  MBEDTLS_ERR_PK_SIG_LEN_MISMATCH if the signature is
- *                  valid but its actual length is less than sig_len,
+ *                  #MBEDTLS_ERR_PK_SIG_LEN_MISMATCH if there is a valid
+ *                  signature in sig but its length is less than \p siglen,
  *                  or a specific error code.
  *
  * \note            For RSA keys, the default padding type is PKCS#1 v1.5.
@@ -285,6 +315,32 @@
                const unsigned char *sig, size_t sig_len );
 
 /**
+ * \brief           Restartable version of \c mbedtls_pk_verify()
+ *
+ * \note            Performs the same job as \c mbedtls_pk_verify(), but can
+ *                  return early and restart according to the limit set with
+ *                  \c mbedtls_ecp_set_max_ops() to reduce blocking for ECC
+ *                  operations. For RSA, same as \c mbedtls_pk_verify().
+ *
+ * \param ctx       PK context to use
+ * \param md_alg    Hash algorithm used (see notes)
+ * \param hash      Hash of the message to sign
+ * \param hash_len  Hash length or 0 (see notes)
+ * \param sig       Signature to verify
+ * \param sig_len   Signature length
+ * \param rs_ctx    Restart context (NULL to disable restart)
+ *
+ * \return          See \c mbedtls_pk_verify(), or
+ * \return          #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
+ *                  operations was reached: see \c mbedtls_ecp_set_max_ops().
+ */
+int mbedtls_pk_verify_restartable( mbedtls_pk_context *ctx,
+               mbedtls_md_type_t md_alg,
+               const unsigned char *hash, size_t hash_len,
+               const unsigned char *sig, size_t sig_len,
+               mbedtls_pk_restart_ctx *rs_ctx );
+
+/**
  * \brief           Verify signature, with options.
  *                  (Includes verification of the padding depending on type.)
  *
@@ -298,10 +354,10 @@
  * \param sig_len   Signature length
  *
  * \return          0 on success (signature is valid),
- *                  MBEDTLS_ERR_PK_TYPE_MISMATCH if the PK context can't be
+ *                  #MBEDTLS_ERR_PK_TYPE_MISMATCH if the PK context can't be
  *                  used for this type of signatures,
- *                  MBEDTLS_ERR_PK_SIG_LEN_MISMATCH if the signature is
- *                  valid but its actual length is less than sig_len,
+ *                  #MBEDTLS_ERR_PK_SIG_LEN_MISMATCH if there is a valid
+ *                  signature in sig but its length is less than \p siglen,
  *                  or a specific error code.
  *
  * \note            If hash_len is 0, then the length associated with md_alg
@@ -348,6 +404,35 @@
              int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
 
 /**
+ * \brief           Restartable version of \c mbedtls_pk_sign()
+ *
+ * \note            Performs the same job as \c mbedtls_pk_sign(), but can
+ *                  return early and restart according to the limit set with
+ *                  \c mbedtls_ecp_set_max_ops() to reduce blocking for ECC
+ *                  operations. For RSA, same as \c mbedtls_pk_sign().
+ *
+ * \param ctx       PK context to use - must hold a private key
+ * \param md_alg    Hash algorithm used (see notes)
+ * \param hash      Hash of the message to sign
+ * \param hash_len  Hash length or 0 (see notes)
+ * \param sig       Place to write the signature
+ * \param sig_len   Number of bytes written
+ * \param f_rng     RNG function
+ * \param p_rng     RNG parameter
+ * \param rs_ctx    Restart context (NULL to disable restart)
+ *
+ * \return          See \c mbedtls_pk_sign(), or
+ * \return          #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
+ *                  operations was reached: see \c mbedtls_ecp_set_max_ops().
+ */
+int mbedtls_pk_sign_restartable( mbedtls_pk_context *ctx,
+             mbedtls_md_type_t md_alg,
+             const unsigned char *hash, size_t hash_len,
+             unsigned char *sig, size_t *sig_len,
+             int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
+             mbedtls_pk_restart_ctx *rs_ctx );
+
+/**
  * \brief           Decrypt message (including padding if relevant).
  *
  * \param ctx       PK context to use - must hold a private key
diff --git a/ext/mbedtls/include/mbedtls/platform.h b/ext/mbedtls/include/mbedtls/platform.h
index 35010f8..89fe8a7 100644
--- a/ext/mbedtls/include/mbedtls/platform.h
+++ b/ext/mbedtls/include/mbedtls/platform.h
@@ -1,9 +1,19 @@
 /**
  * \file platform.h
  *
- * \brief mbed TLS Platform abstraction layer
+ * \brief This file contains the definitions and functions of the
+ *        Mbed TLS platform abstraction layer.
  *
- *  Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
+ *        The platform abstraction layer removes the need for the library
+ *        to directly link to standard C library functions or operating
+ *        system services, making the library easier to port and embed.
+ *        Application developers and users of the library can provide their own
+ *        implementations of these functions, or implementations specific to
+ *        their platform, which can be statically linked to the library or
+ *        dynamically configured at runtime.
+ */
+/*
+ *  Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved
  *  SPDX-License-Identifier: Apache-2.0
  *
  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
@@ -18,7 +28,7 @@
  *  See the License for the specific language governing permissions and
  *  limitations under the License.
  *
- *  This file is part of mbed TLS (https://tls.mbed.org)
+ *  This file is part of Mbed TLS (https://tls.mbed.org)
  */
 #ifndef MBEDTLS_PLATFORM_H
 #define MBEDTLS_PLATFORM_H
@@ -30,9 +40,12 @@
 #endif
 
 #if defined(MBEDTLS_HAVE_TIME)
-#include "mbedtls/platform_time.h"
+#include "platform_time.h"
 #endif
 
+#define MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED     -0x0070 /**< Hardware accelerator failed */
+#define MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED -0x0072 /**< The requested feature is not supported by the platform */
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -51,34 +64,34 @@
 #include <time.h>
 #if !defined(MBEDTLS_PLATFORM_STD_SNPRINTF)
 #if defined(_WIN32)
-#define MBEDTLS_PLATFORM_STD_SNPRINTF   mbedtls_platform_win32_snprintf /**< Default snprintf to use  */
+#define MBEDTLS_PLATFORM_STD_SNPRINTF   mbedtls_platform_win32_snprintf /**< The default \c snprintf function to use.  */
 #else
-#define MBEDTLS_PLATFORM_STD_SNPRINTF   snprintf /**< Default snprintf to use  */
+#define MBEDTLS_PLATFORM_STD_SNPRINTF   snprintf /**< The default \c snprintf function to use.  */
 #endif
 #endif
 #if !defined(MBEDTLS_PLATFORM_STD_PRINTF)
-#define MBEDTLS_PLATFORM_STD_PRINTF   printf /**< Default printf to use  */
+#define MBEDTLS_PLATFORM_STD_PRINTF   printf /**< The default \c printf function to use. */
 #endif
 #if !defined(MBEDTLS_PLATFORM_STD_FPRINTF)
-#define MBEDTLS_PLATFORM_STD_FPRINTF fprintf /**< Default fprintf to use */
+#define MBEDTLS_PLATFORM_STD_FPRINTF fprintf /**< The default \c fprintf function to use. */
 #endif
 #if !defined(MBEDTLS_PLATFORM_STD_CALLOC)
-#define MBEDTLS_PLATFORM_STD_CALLOC   calloc /**< Default allocator to use */
+#define MBEDTLS_PLATFORM_STD_CALLOC   calloc /**< The default \c calloc function to use. */
 #endif
 #if !defined(MBEDTLS_PLATFORM_STD_FREE)
-#define MBEDTLS_PLATFORM_STD_FREE       free /**< Default free to use */
+#define MBEDTLS_PLATFORM_STD_FREE       free /**< The default \c free function to use. */
 #endif
 #if !defined(MBEDTLS_PLATFORM_STD_EXIT)
-#define MBEDTLS_PLATFORM_STD_EXIT      exit /**< Default exit to use */
+#define MBEDTLS_PLATFORM_STD_EXIT      exit /**< The default \c exit function to use. */
 #endif
 #if !defined(MBEDTLS_PLATFORM_STD_TIME)
-#define MBEDTLS_PLATFORM_STD_TIME       time    /**< Default time to use */
+#define MBEDTLS_PLATFORM_STD_TIME       time    /**< The default \c time function to use. */
 #endif
 #if !defined(MBEDTLS_PLATFORM_STD_EXIT_SUCCESS)
-#define MBEDTLS_PLATFORM_STD_EXIT_SUCCESS  EXIT_SUCCESS /**< Default exit value to use */
+#define MBEDTLS_PLATFORM_STD_EXIT_SUCCESS  EXIT_SUCCESS /**< The default exit value to use. */
 #endif
 #if !defined(MBEDTLS_PLATFORM_STD_EXIT_FAILURE)
-#define MBEDTLS_PLATFORM_STD_EXIT_FAILURE  EXIT_FAILURE /**< Default exit value to use */
+#define MBEDTLS_PLATFORM_STD_EXIT_FAILURE  EXIT_FAILURE /**< The default exit value to use. */
 #endif
 #if defined(MBEDTLS_FS_IO)
 #if !defined(MBEDTLS_PLATFORM_STD_NV_SEED_READ)
@@ -101,7 +114,7 @@
 /* \} name SECTION: Module settings */
 
 /*
- * The function pointers for calloc and free
+ * The function pointers for calloc and free.
  */
 #if defined(MBEDTLS_PLATFORM_MEMORY)
 #if defined(MBEDTLS_PLATFORM_FREE_MACRO) && \
@@ -111,16 +124,17 @@
 #else
 /* For size_t */
 #include <stddef.h>
-extern void * (*mbedtls_calloc)( size_t n, size_t size );
-extern void (*mbedtls_free)( void *ptr );
+extern void *mbedtls_calloc( size_t n, size_t size );
+extern void mbedtls_free( void *ptr );
 
 /**
- * \brief   Set your own memory implementation function pointers
+ * \brief               This function dynamically sets the memory-management
+ *                      functions used by the library, during runtime.
  *
- * \param calloc_func   the calloc function implementation
- * \param free_func     the free function implementation
+ * \param calloc_func   The \c calloc function implementation.
+ * \param free_func     The \c free function implementation.
  *
- * \return              0 if successful
+ * \return              \c 0.
  */
 int mbedtls_platform_set_calloc_free( void * (*calloc_func)( size_t, size_t ),
                               void (*free_func)( void * ) );
@@ -139,11 +153,13 @@
 extern int (*mbedtls_fprintf)( FILE *stream, const char *format, ... );
 
 /**
- * \brief   Set your own fprintf function pointer
+ * \brief                This function dynamically configures the fprintf
+ *                       function that is called when the
+ *                       mbedtls_fprintf() function is invoked by the library.
  *
- * \param fprintf_func   the fprintf function implementation
+ * \param fprintf_func   The \c fprintf function implementation.
  *
- * \return              0
+ * \return               \c 0.
  */
 int mbedtls_platform_set_fprintf( int (*fprintf_func)( FILE *stream, const char *,
                                                ... ) );
@@ -162,11 +178,13 @@
 extern int (*mbedtls_printf)( const char *format, ... );
 
 /**
- * \brief   Set your own printf function pointer
+ * \brief               This function dynamically configures the snprintf
+ *                      function that is called when the mbedtls_snprintf()
+ *                      function is invoked by the library.
  *
- * \param printf_func   the printf function implementation
+ * \param printf_func   The \c printf function implementation.
  *
- * \return              0
+ * \return              \c 0 on success.
  */
 int mbedtls_platform_set_printf( int (*printf_func)( const char *, ... ) );
 #else /* !MBEDTLS_PLATFORM_PRINTF_ALT */
@@ -195,11 +213,12 @@
 extern int (*mbedtls_snprintf)( char * s, size_t n, const char * format, ... );
 
 /**
- * \brief   Set your own snprintf function pointer
+ * \brief                 This function allows configuring a custom
+ *                        \c snprintf function pointer.
  *
- * \param snprintf_func   the snprintf function implementation
+ * \param snprintf_func   The \c snprintf function implementation.
  *
- * \return              0
+ * \return                \c 0 on success.
  */
 int mbedtls_platform_set_snprintf( int (*snprintf_func)( char * s, size_t n,
                                                  const char * format, ... ) );
@@ -207,7 +226,7 @@
 #if defined(MBEDTLS_PLATFORM_SNPRINTF_MACRO)
 #define mbedtls_snprintf   MBEDTLS_PLATFORM_SNPRINTF_MACRO
 #else
-#define mbedtls_snprintf   snprintf
+#define mbedtls_snprintf   MBEDTLS_PLATFORM_STD_SNPRINTF
 #endif /* MBEDTLS_PLATFORM_SNPRINTF_MACRO */
 #endif /* MBEDTLS_PLATFORM_SNPRINTF_ALT */
 
@@ -218,11 +237,13 @@
 extern void (*mbedtls_exit)( int status );
 
 /**
- * \brief   Set your own exit function pointer
+ * \brief             This function dynamically configures the exit
+ *                    function that is called when the mbedtls_exit()
+ *                    function is invoked by the library.
  *
- * \param exit_func   the exit function implementation
+ * \param exit_func   The \c exit function implementation.
  *
- * \return              0
+ * \return            \c 0 on success.
  */
 int mbedtls_platform_set_exit( void (*exit_func)( int status ) );
 #else
@@ -265,12 +286,13 @@
 extern int (*mbedtls_nv_seed_write)( unsigned char *buf, size_t buf_len );
 
 /**
- * \brief   Set your own seed file writing/reading functions
+ * \brief   This function allows configuring custom seed file writing and
+ *          reading functions.
  *
- * \param   nv_seed_read_func   the seed reading function implementation
- * \param   nv_seed_write_func  the seed writing function implementation
+ * \param   nv_seed_read_func   The seed reading function implementation.
+ * \param   nv_seed_write_func  The seed writing function implementation.
  *
- * \return              0
+ * \return  \c 0 on success.
  */
 int mbedtls_platform_set_nv_seed(
             int (*nv_seed_read_func)( unsigned char *buf, size_t buf_len ),
@@ -291,13 +313,14 @@
 #if !defined(MBEDTLS_PLATFORM_SETUP_TEARDOWN_ALT)
 
 /**
- * \brief   Platform context structure
+ * \brief   The platform context structure.
  *
  * \note    This structure may be used to assist platform-specific
- *          setup/teardown operations.
+ *          setup or teardown operations.
  */
-typedef struct {
-    char dummy; /**< Placeholder member as empty structs are not portable */
+typedef struct mbedtls_platform_context
+{
+    char dummy; /**< A placeholder member, as empty structs are not portable. */
 }
 mbedtls_platform_context;
 
@@ -306,33 +329,34 @@
 #endif /* !MBEDTLS_PLATFORM_SETUP_TEARDOWN_ALT */
 
 /**
- * \brief   Perform any platform initialisation operations
+ * \brief   This function performs any platform-specific initialization
+ *          operations.
  *
- * \param   ctx     mbed TLS context
+ * \note    This function should be called before any other library functions.
  *
- * \return  0 if successful
+ *          Its implementation is platform-specific, and unless
+ *          platform-specific code is provided, it does nothing.
  *
- * \note    This function is intended to allow platform specific initialisation,
- *          and should be called before any other library functions. Its
- *          implementation is platform specific, and by default, unless platform
- *          specific code is provided, it does nothing.
+ * \note    The usage and necessity of this function is dependent on the platform.
  *
- *          Its use and whether its necessary to be called is dependent on the
- *          platform.
+ * \param   ctx     The platform context.
+ *
+ * \return  \c 0 on success.
  */
 int mbedtls_platform_setup( mbedtls_platform_context *ctx );
 /**
- * \brief   Perform any platform teardown operations
+ * \brief   This function performs any platform teardown operations.
  *
- * \param   ctx     mbed TLS context
+ * \note    This function should be called after every other Mbed TLS module
+ *          has been correctly freed using the appropriate free function.
  *
- * \note    This function should be called after every other mbed TLS module has
- *          been correctly freed using the appropriate free function.
- *          Its implementation is platform specific, and by default, unless
- *          platform specific code is provided, it does nothing.
+ *          Its implementation is platform-specific, and unless
+ *          platform-specific code is provided, it does nothing.
  *
- *          Its use and whether its necessary to be called is dependent on the
- *          platform.
+ * \note    The usage and necessity of this function is dependent on the platform.
+ *
+ * \param   ctx     The platform context.
+ *
  */
 void mbedtls_platform_teardown( mbedtls_platform_context *ctx );
 
diff --git a/ext/mbedtls/include/mbedtls/platform_util.h b/ext/mbedtls/include/mbedtls/platform_util.h
new file mode 100644
index 0000000..164a1a0
--- /dev/null
+++ b/ext/mbedtls/include/mbedtls/platform_util.h
@@ -0,0 +1,103 @@
+/**
+ * \file platform_util.h
+ *
+ * \brief Common and shared functions used by multiple modules in the Mbed TLS
+ *        library.
+ */
+/*
+ *  Copyright (C) 2018, Arm Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  This file is part of Mbed TLS (https://tls.mbed.org)
+ */
+#ifndef MBEDTLS_PLATFORM_UTIL_H
+#define MBEDTLS_PLATFORM_UTIL_H
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#include <stddef.h>
+#if defined(MBEDTLS_HAVE_TIME_DATE)
+#include "mbedtls/platform_time.h"
+#include <time.h>
+#endif /* MBEDTLS_HAVE_TIME_DATE */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \brief       Securely zeroize a buffer
+ *
+ *              The function is meant to wipe the data contained in a buffer so
+ *              that it can no longer be recovered even if the program memory
+ *              is later compromised. Call this function on sensitive data
+ *              stored on the stack before returning from a function, and on
+ *              sensitive data stored on the heap before freeing the heap
+ *              object.
+ *
+ *              It is extremely difficult to guarantee that calls to
+ *              mbedtls_platform_zeroize() are not removed by aggressive
+ *              compiler optimizations in a portable way. For this reason, Mbed
+ *              TLS provides the configuration option
+ *              MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure
+ *              mbedtls_platform_zeroize() to use a suitable implementation for
+ *              their platform and needs
+ *
+ * \param buf   Buffer to be zeroized
+ * \param len   Length of the buffer in bytes
+ *
+ */
+void mbedtls_platform_zeroize( void *buf, size_t len );
+
+#if defined(MBEDTLS_HAVE_TIME_DATE)
+/**
+ * \brief      Platform-specific implementation of gmtime_r()
+ *
+ *             The function is a thread-safe abstraction that behaves
+ *             similarly to the gmtime_r() function from Unix/POSIX.
+ *
+ *             Mbed TLS will try to identify the underlying platform and
+ *             make use of an appropriate underlying implementation (e.g.
+ *             gmtime_r() for POSIX and gmtime_s() for Windows). If this is
+ *             not possible, then gmtime() will be used. In this case, calls
+ *             from the library to gmtime() will be guarded by the mutex
+ *             mbedtls_threading_gmtime_mutex if MBEDTLS_THREADING_C is
+ *             enabled. It is recommended that calls from outside the library
+ *             are also guarded by this mutex.
+ *
+ *             If MBEDTLS_PLATFORM_GMTIME_R_ALT is defined, then Mbed TLS will
+ *             unconditionally use the alternative implementation for
+ *             mbedtls_platform_gmtime_r() supplied by the user at compile time.
+ *
+ * \param tt     Pointer to an object containing time (in seconds) since the
+ *               epoch to be converted
+ * \param tm_buf Pointer to an object where the results will be stored
+ *
+ * \return      Pointer to an object of type struct tm on success, otherwise
+ *              NULL
+ */
+struct tm *mbedtls_platform_gmtime_r( const mbedtls_time_t *tt,
+                                      struct tm *tm_buf );
+#endif /* MBEDTLS_HAVE_TIME_DATE */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* MBEDTLS_PLATFORM_UTIL_H */
diff --git a/ext/mbedtls/include/mbedtls/threading.h b/ext/mbedtls/include/mbedtls/threading.h
new file mode 100644
index 0000000..92e6e6b
--- /dev/null
+++ b/ext/mbedtls/include/mbedtls/threading.h
@@ -0,0 +1,122 @@
+/**
+ * \file threading.h
+ *
+ * \brief Threading abstraction layer
+ */
+/*
+ *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  This file is part of mbed TLS (https://tls.mbed.org)
+ */
+#ifndef MBEDTLS_THREADING_H
+#define MBEDTLS_THREADING_H
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#include <stdlib.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* MBEDTLS_ERR_THREADING_FEATURE_UNAVAILABLE is deprecated and should not be
+ * used. */
+#define MBEDTLS_ERR_THREADING_FEATURE_UNAVAILABLE         -0x001A  /**< The selected feature is not available. */
+
+#define MBEDTLS_ERR_THREADING_BAD_INPUT_DATA              -0x001C  /**< Bad input parameters to function. */
+#define MBEDTLS_ERR_THREADING_MUTEX_ERROR                 -0x001E  /**< Locking / unlocking / free failed with error code. */
+
+#if defined(MBEDTLS_THREADING_PTHREAD)
+#include <pthread.h>
+typedef struct mbedtls_threading_mutex_t
+{
+    pthread_mutex_t mutex;
+    char is_valid;
+} mbedtls_threading_mutex_t;
+#endif
+
+#if defined(MBEDTLS_THREADING_ALT)
+/* You should define the mbedtls_threading_mutex_t type in your header */
+#include "threading_alt.h"
+
+/**
+ * \brief           Set your alternate threading implementation function
+ *                  pointers and initialize global mutexes. If used, this
+ *                  function must be called once in the main thread before any
+ *                  other mbed TLS function is called, and
+ *                  mbedtls_threading_free_alt() must be called once in the main
+ *                  thread after all other mbed TLS functions.
+ *
+ * \note            mutex_init() and mutex_free() don't return a status code.
+ *                  If mutex_init() fails, it should leave its argument (the
+ *                  mutex) in a state such that mutex_lock() will fail when
+ *                  called with this argument.
+ *
+ * \param mutex_init    the init function implementation
+ * \param mutex_free    the free function implementation
+ * \param mutex_lock    the lock function implementation
+ * \param mutex_unlock  the unlock function implementation
+ */
+void mbedtls_threading_set_alt( void (*mutex_init)( mbedtls_threading_mutex_t * ),
+                       void (*mutex_free)( mbedtls_threading_mutex_t * ),
+                       int (*mutex_lock)( mbedtls_threading_mutex_t * ),
+                       int (*mutex_unlock)( mbedtls_threading_mutex_t * ) );
+
+/**
+ * \brief               Free global mutexes.
+ */
+void mbedtls_threading_free_alt( void );
+#endif /* MBEDTLS_THREADING_ALT */
+
+#if defined(MBEDTLS_THREADING_C)
+/*
+ * The function pointers for mutex_init, mutex_free, mutex_ and mutex_unlock
+ *
+ * All these functions are expected to work or the result will be undefined.
+ */
+extern void (*mbedtls_mutex_init)( mbedtls_threading_mutex_t *mutex );
+extern void (*mbedtls_mutex_free)( mbedtls_threading_mutex_t *mutex );
+extern int (*mbedtls_mutex_lock)( mbedtls_threading_mutex_t *mutex );
+extern int (*mbedtls_mutex_unlock)( mbedtls_threading_mutex_t *mutex );
+
+/*
+ * Global mutexes
+ */
+#if defined(MBEDTLS_FS_IO)
+extern mbedtls_threading_mutex_t mbedtls_threading_readdir_mutex;
+#endif
+
+#if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_R_ALT)
+/* This mutex may or may not be used in the default definition of
+ * mbedtls_platform_gmtime_r(), but in order to determine that,
+ * we need to check POSIX features, hence modify _POSIX_C_SOURCE.
+ * With the current approach, this declaration is orphaned, lacking
+ * an accompanying definition, in case mbedtls_platform_gmtime_r()
+ * doesn't need it, but that's not a problem. */
+extern mbedtls_threading_mutex_t mbedtls_threading_gmtime_mutex;
+#endif /* MBEDTLS_HAVE_TIME_DATE && !MBEDTLS_PLATFORM_GMTIME_R_ALT */
+
+#endif /* MBEDTLS_THREADING_C */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* threading.h */
diff --git a/ext/mbedtls/src/asn1parse.c b/ext/mbedtls/src/asn1parse.c
index 4dd65c0..171c340 100644
--- a/ext/mbedtls/src/asn1parse.c
+++ b/ext/mbedtls/src/asn1parse.c
@@ -28,6 +28,7 @@
 #if defined(MBEDTLS_ASN1_PARSE_C)
 
 #include "mbedtls/asn1.h"
+#include "mbedtls/platform_util.h"
 
 #include <string.h>
 
@@ -43,11 +44,6 @@
 #define mbedtls_free       free
 #endif
 
-/* Implementation that should never be optimized out by the compiler */
-static void mbedtls_zeroize( void *v, size_t n ) {
-    volatile unsigned char *p = (unsigned char*)v; while( n-- ) *p++ = 0;
-}
-
 /*
  * ASN.1 DER decoding routines
  */
@@ -313,7 +309,7 @@
 
     if( *p == end )
     {
-        mbedtls_zeroize( params, sizeof(mbedtls_asn1_buf) );
+        mbedtls_platform_zeroize( params, sizeof(mbedtls_asn1_buf) );
         return( 0 );
     }
 
@@ -358,7 +354,7 @@
     mbedtls_free( cur->oid.p );
     mbedtls_free( cur->val.p );
 
-    mbedtls_zeroize( cur, sizeof( mbedtls_asn1_named_data ) );
+    mbedtls_platform_zeroize( cur, sizeof( mbedtls_asn1_named_data ) );
 }
 
 void mbedtls_asn1_free_named_data_list( mbedtls_asn1_named_data **head )
diff --git a/ext/mbedtls/src/platform_util.c b/ext/mbedtls/src/platform_util.c
new file mode 100644
index 0000000..ca5fe4f
--- /dev/null
+++ b/ext/mbedtls/src/platform_util.c
@@ -0,0 +1,135 @@
+/*
+ * Common and shared functions used by multiple modules in the Mbed TLS
+ * library.
+ *
+ *  Copyright (C) 2018, Arm Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  This file is part of Mbed TLS (https://tls.mbed.org)
+ */
+
+/*
+ * Ensure gmtime_r is available even with -std=c99; must be defined before
+ * config.h, which pulls in glibc's features.h. Harmless on other platforms.
+ */
+#if !defined(_POSIX_C_SOURCE)
+#define _POSIX_C_SOURCE 200112L
+#endif
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#include "mbedtls/platform_util.h"
+#include "mbedtls/threading.h"
+
+#include <stddef.h>
+#include <string.h>
+
+#if !defined(MBEDTLS_PLATFORM_ZEROIZE_ALT)
+/*
+ * This implementation should never be optimized out by the compiler
+ *
+ * This implementation for mbedtls_platform_zeroize() was inspired from Colin
+ * Percival's blog article at:
+ *
+ * http://www.daemonology.net/blog/2014-09-04-how-to-zero-a-buffer.html
+ *
+ * It uses a volatile function pointer to the standard memset(). Because the
+ * pointer is volatile the compiler expects it to change at
+ * any time and will not optimize out the call that could potentially perform
+ * other operations on the input buffer instead of just setting it to 0.
+ * Nevertheless, as pointed out by davidtgoldblatt on Hacker News
+ * (refer to http://www.daemonology.net/blog/2014-09-05-erratum.html for
+ * details), optimizations of the following form are still possible:
+ *
+ * if( memset_func != memset )
+ *     memset_func( buf, 0, len );
+ *
+ * Note that it is extremely difficult to guarantee that
+ * mbedtls_platform_zeroize() will not be optimized out by aggressive compilers
+ * in a portable way. For this reason, Mbed TLS also provides the configuration
+ * option MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure
+ * mbedtls_platform_zeroize() to use a suitable implementation for their
+ * platform and needs.
+ */
+static void * (* const volatile memset_func)( void *, int, size_t ) = memset;
+
+void mbedtls_platform_zeroize( void *buf, size_t len )
+{
+    memset_func( buf, 0, len );
+}
+#endif /* MBEDTLS_PLATFORM_ZEROIZE_ALT */
+
+#if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_R_ALT)
+#include <time.h>
+#if !defined(_WIN32) && (defined(unix) || \
+    defined(__unix) || defined(__unix__) || (defined(__APPLE__) && \
+    defined(__MACH__)))
+#include <unistd.h>
+#endif /* !_WIN32 && (unix || __unix || __unix__ ||
+        * (__APPLE__ && __MACH__)) */
+
+#if !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) ||     \
+       ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) &&                     \
+         _POSIX_THREAD_SAFE_FUNCTIONS >= 20112L ) )
+/*
+ * This is a convenience shorthand macro to avoid checking the long
+ * preprocessor conditions above. Ideally, we could expose this macro in
+ * platform_util.h and simply use it in platform_util.c, threading.c and
+ * threading.h. However, this macro is not part of the Mbed TLS public API, so
+ * we keep it private by only defining it in this file
+ */
+#if ! ( defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) )
+#define PLATFORM_UTIL_USE_GMTIME
+#endif /* ! ( defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) ) */
+
+#endif /* !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) ||     \
+             ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) &&                     \
+                _POSIX_THREAD_SAFE_FUNCTIONS >= 20112L ) ) */
+
+struct tm *mbedtls_platform_gmtime_r( const mbedtls_time_t *tt,
+                                      struct tm *tm_buf )
+{
+#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
+    return( ( gmtime_s( tm_buf, tt ) == 0 ) ? tm_buf : NULL );
+#elif !defined(PLATFORM_UTIL_USE_GMTIME)
+    return( gmtime_r( tt, tm_buf ) );
+#else
+    struct tm *lt;
+
+#if defined(MBEDTLS_THREADING_C)
+    if( mbedtls_mutex_lock( &mbedtls_threading_gmtime_mutex ) != 0 )
+        return( NULL );
+#endif /* MBEDTLS_THREADING_C */
+
+    lt = gmtime( tt );
+
+    if( lt != NULL )
+    {
+        memcpy( tm_buf, lt, sizeof( struct tm ) );
+    }
+
+#if defined(MBEDTLS_THREADING_C)
+    if( mbedtls_mutex_unlock( &mbedtls_threading_gmtime_mutex ) != 0 )
+        return( NULL );
+#endif /* MBEDTLS_THREADING_C */
+
+    return( ( lt == NULL ) ? NULL : tm_buf );
+#endif /* _WIN32 && !EFIX64 && !EFI32 */
+}
+#endif /* MBEDTLS_HAVE_TIME_DATE && MBEDTLS_PLATFORM_GMTIME_R_ALT */