diff --git a/library/x509_crt.c b/library/x509_crt.c
new file mode 100644
index 0000000..605d8ef
--- /dev/null
+++ b/library/x509_crt.c
@@ -0,0 +1,2879 @@
+/*
+ *  X.509 certificate parsing and verification
+ *
+ *  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)
+ */
+/*
+ *  The ITU-T X.509 standard defines a certificate format for PKI.
+ *
+ *  http://www.ietf.org/rfc/rfc5280.txt (Certificates and CRLs)
+ *  http://www.ietf.org/rfc/rfc3279.txt (Alg IDs for CRLs)
+ *  http://www.ietf.org/rfc/rfc2986.txt (CSRs, aka PKCS#10)
+ *
+ *  http://www.itu.int/ITU-T/studygroups/com17/languages/X.680-0207.pdf
+ *  http://www.itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf
+ *
+ *  [SIRO] https://cabforum.org/wp-content/uploads/Chunghwatelecom201503cabforumV4.pdf
+ */
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+
+#include "mbedtls/x509_crt.h"
+#include "mbedtls/oid.h"
+#include "mbedtls/platform_util.h"
+
+#include <string.h>
+
+#if defined(MBEDTLS_PEM_PARSE_C)
+#include "mbedtls/pem.h"
+#endif
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+#include "psa/crypto.h"
+#include "mbedtls/psa_util.h"
+#endif
+
+#if defined(MBEDTLS_PLATFORM_C)
+#include "mbedtls/platform.h"
+#else
+#include <stdio.h>
+#include <stdlib.h>
+#define mbedtls_free       free
+#define mbedtls_calloc    calloc
+#define mbedtls_snprintf   snprintf
+#endif
+
+#if defined(MBEDTLS_THREADING_C)
+#include "mbedtls/threading.h"
+#endif
+
+#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
+#include <windows.h>
+#else
+#include <time.h>
+#endif
+
+#if defined(MBEDTLS_FS_IO)
+#include <stdio.h>
+#if !defined(_WIN32) || defined(EFIX64) || defined(EFI32)
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <dirent.h>
+#endif /* !_WIN32 || EFIX64 || EFI32 */
+#endif
+
+/*
+ * Item in a verification chain: cert and flags for it
+ */
+typedef struct {
+    mbedtls_x509_crt *crt;
+    uint32_t flags;
+} x509_crt_verify_chain_item;
+
+/*
+ * Max size of verification chain: end-entity + intermediates + trusted root
+ */
+#define X509_MAX_VERIFY_CHAIN_SIZE    ( MBEDTLS_X509_MAX_INTERMEDIATE_CA + 2 )
+
+/*
+ * Default profile
+ */
+const mbedtls_x509_crt_profile mbedtls_x509_crt_profile_default =
+{
+#if defined(MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_CERTIFICATES)
+    /* Allow SHA-1 (weak, but still safe in controlled environments) */
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA1 ) |
+#endif
+    /* Only SHA-2 hashes */
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA224 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA256 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA384 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA512 ),
+    0xFFFFFFF, /* Any PK alg    */
+    0xFFFFFFF, /* Any curve     */
+    2048,
+};
+
+/*
+ * Next-default profile
+ */
+const mbedtls_x509_crt_profile mbedtls_x509_crt_profile_next =
+{
+    /* Hashes from SHA-256 and above */
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA256 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA384 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA512 ),
+    0xFFFFFFF, /* Any PK alg    */
+#if defined(MBEDTLS_ECP_C)
+    /* Curves at or above 128-bit security level */
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_ECP_DP_SECP256R1 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_ECP_DP_SECP384R1 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_ECP_DP_SECP521R1 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_ECP_DP_BP256R1 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_ECP_DP_BP384R1 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_ECP_DP_BP512R1 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_ECP_DP_SECP256K1 ),
+#else
+    0,
+#endif
+    2048,
+};
+
+/*
+ * NSA Suite B Profile
+ */
+const mbedtls_x509_crt_profile mbedtls_x509_crt_profile_suiteb =
+{
+    /* Only SHA-256 and 384 */
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA256 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA384 ),
+    /* Only ECDSA */
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_PK_ECDSA ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_PK_ECKEY ),
+#if defined(MBEDTLS_ECP_C)
+    /* Only NIST P-256 and P-384 */
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_ECP_DP_SECP256R1 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_ECP_DP_SECP384R1 ),
+#else
+    0,
+#endif
+    0,
+};
+
+/*
+ * Check md_alg against profile
+ * Return 0 if md_alg is acceptable for this profile, -1 otherwise
+ */
+static int x509_profile_check_md_alg( const mbedtls_x509_crt_profile *profile,
+                                      mbedtls_md_type_t md_alg )
+{
+    if( md_alg == MBEDTLS_MD_NONE )
+        return( -1 );
+
+    if( ( profile->allowed_mds & MBEDTLS_X509_ID_FLAG( md_alg ) ) != 0 )
+        return( 0 );
+
+    return( -1 );
+}
+
+/*
+ * Check pk_alg against profile
+ * Return 0 if pk_alg is acceptable for this profile, -1 otherwise
+ */
+static int x509_profile_check_pk_alg( const mbedtls_x509_crt_profile *profile,
+                                      mbedtls_pk_type_t pk_alg )
+{
+    if( pk_alg == MBEDTLS_PK_NONE )
+        return( -1 );
+
+    if( ( profile->allowed_pks & MBEDTLS_X509_ID_FLAG( pk_alg ) ) != 0 )
+        return( 0 );
+
+    return( -1 );
+}
+
+/*
+ * Check key against profile
+ * Return 0 if pk is acceptable for this profile, -1 otherwise
+ */
+static int x509_profile_check_key( const mbedtls_x509_crt_profile *profile,
+                                   const mbedtls_pk_context *pk )
+{
+    const mbedtls_pk_type_t pk_alg = mbedtls_pk_get_type( pk );
+
+#if defined(MBEDTLS_RSA_C)
+    if( pk_alg == MBEDTLS_PK_RSA || pk_alg == MBEDTLS_PK_RSASSA_PSS )
+    {
+        if( mbedtls_pk_get_bitlen( pk ) >= profile->rsa_min_bitlen )
+            return( 0 );
+
+        return( -1 );
+    }
+#endif
+
+#if defined(MBEDTLS_ECP_C)
+    if( pk_alg == MBEDTLS_PK_ECDSA ||
+        pk_alg == MBEDTLS_PK_ECKEY ||
+        pk_alg == MBEDTLS_PK_ECKEY_DH )
+    {
+        const mbedtls_ecp_group_id gid = mbedtls_pk_ec( *pk )->grp.id;
+
+        if( gid == MBEDTLS_ECP_DP_NONE )
+            return( -1 );
+
+        if( ( profile->allowed_curves & MBEDTLS_X509_ID_FLAG( gid ) ) != 0 )
+            return( 0 );
+
+        return( -1 );
+    }
+#endif
+
+    return( -1 );
+}
+
+/*
+ * Like memcmp, but case-insensitive and always returns -1 if different
+ */
+static int x509_memcasecmp( const void *s1, const void *s2, size_t len )
+{
+    size_t i;
+    unsigned char diff;
+    const unsigned char *n1 = s1, *n2 = s2;
+
+    for( i = 0; i < len; i++ )
+    {
+        diff = n1[i] ^ n2[i];
+
+        if( diff == 0 )
+            continue;
+
+        if( diff == 32 &&
+            ( ( n1[i] >= 'a' && n1[i] <= 'z' ) ||
+              ( n1[i] >= 'A' && n1[i] <= 'Z' ) ) )
+        {
+            continue;
+        }
+
+        return( -1 );
+    }
+
+    return( 0 );
+}
+
+/*
+ * Return 0 if name matches wildcard, -1 otherwise
+ */
+static int x509_check_wildcard( const char *cn, const mbedtls_x509_buf *name )
+{
+    size_t i;
+    size_t cn_idx = 0, cn_len = strlen( cn );
+
+    /* We can't have a match if there is no wildcard to match */
+    if( name->len < 3 || name->p[0] != '*' || name->p[1] != '.' )
+        return( -1 );
+
+    for( i = 0; i < cn_len; ++i )
+    {
+        if( cn[i] == '.' )
+        {
+            cn_idx = i;
+            break;
+        }
+    }
+
+    if( cn_idx == 0 )
+        return( -1 );
+
+    if( cn_len - cn_idx == name->len - 1 &&
+        x509_memcasecmp( name->p + 1, cn + cn_idx, name->len - 1 ) == 0 )
+    {
+        return( 0 );
+    }
+
+    return( -1 );
+}
+
+/*
+ * Compare two X.509 strings, case-insensitive, and allowing for some encoding
+ * variations (but not all).
+ *
+ * Return 0 if equal, -1 otherwise.
+ */
+static int x509_string_cmp( const mbedtls_x509_buf *a, const mbedtls_x509_buf *b )
+{
+    if( a->tag == b->tag &&
+        a->len == b->len &&
+        memcmp( a->p, b->p, b->len ) == 0 )
+    {
+        return( 0 );
+    }
+
+    if( ( a->tag == MBEDTLS_ASN1_UTF8_STRING || a->tag == MBEDTLS_ASN1_PRINTABLE_STRING ) &&
+        ( b->tag == MBEDTLS_ASN1_UTF8_STRING || b->tag == MBEDTLS_ASN1_PRINTABLE_STRING ) &&
+        a->len == b->len &&
+        x509_memcasecmp( a->p, b->p, b->len ) == 0 )
+    {
+        return( 0 );
+    }
+
+    return( -1 );
+}
+
+/*
+ * Compare two X.509 Names (aka rdnSequence).
+ *
+ * See RFC 5280 section 7.1, though we don't implement the whole algorithm:
+ * we sometimes return unequal when the full algorithm would return equal,
+ * but never the other way. (In particular, we don't do Unicode normalisation
+ * or space folding.)
+ *
+ * Return 0 if equal, -1 otherwise.
+ */
+static int x509_name_cmp( const mbedtls_x509_name *a, const mbedtls_x509_name *b )
+{
+    /* Avoid recursion, it might not be optimised by the compiler */
+    while( a != NULL || b != NULL )
+    {
+        if( a == NULL || b == NULL )
+            return( -1 );
+
+        /* type */
+        if( a->oid.tag != b->oid.tag ||
+            a->oid.len != b->oid.len ||
+            memcmp( a->oid.p, b->oid.p, b->oid.len ) != 0 )
+        {
+            return( -1 );
+        }
+
+        /* value */
+        if( x509_string_cmp( &a->val, &b->val ) != 0 )
+            return( -1 );
+
+        /* structure of the list of sets */
+        if( a->next_merged != b->next_merged )
+            return( -1 );
+
+        a = a->next;
+        b = b->next;
+    }
+
+    /* a == NULL == b */
+    return( 0 );
+}
+
+/*
+ * Reset (init or clear) a verify_chain
+ */
+static void x509_crt_verify_chain_reset(
+    mbedtls_x509_crt_verify_chain *ver_chain )
+{
+    size_t i;
+
+    for( i = 0; i < MBEDTLS_X509_MAX_VERIFY_CHAIN_SIZE; i++ )
+    {
+        ver_chain->items[i].crt = NULL;
+        ver_chain->items[i].flags = (uint32_t) -1;
+    }
+
+    ver_chain->len = 0;
+
+#if defined(MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK)
+    ver_chain->trust_ca_cb_result = NULL;
+#endif /* MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK */
+}
+
+/*
+ *  Version  ::=  INTEGER  {  v1(0), v2(1), v3(2)  }
+ */
+static int x509_get_version( unsigned char **p,
+                             const unsigned char *end,
+                             int *ver )
+{
+    int ret;
+    size_t len;
+
+    if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
+            MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | 0 ) ) != 0 )
+    {
+        if( ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
+        {
+            *ver = 0;
+            return( 0 );
+        }
+
+        return( ret );
+    }
+
+    end = *p + len;
+
+    if( ( ret = mbedtls_asn1_get_int( p, end, ver ) ) != 0 )
+        return( MBEDTLS_ERR_X509_INVALID_VERSION + ret );
+
+    if( *p != end )
+        return( MBEDTLS_ERR_X509_INVALID_VERSION +
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+
+    return( 0 );
+}
+
+/*
+ *  Validity ::= SEQUENCE {
+ *       notBefore      Time,
+ *       notAfter       Time }
+ */
+static int x509_get_dates( unsigned char **p,
+                           const unsigned char *end,
+                           mbedtls_x509_time *from,
+                           mbedtls_x509_time *to )
+{
+    int ret;
+    size_t len;
+
+    if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
+            MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
+        return( MBEDTLS_ERR_X509_INVALID_DATE + ret );
+
+    end = *p + len;
+
+    if( ( ret = mbedtls_x509_get_time( p, end, from ) ) != 0 )
+        return( ret );
+
+    if( ( ret = mbedtls_x509_get_time( p, end, to ) ) != 0 )
+        return( ret );
+
+    if( *p != end )
+        return( MBEDTLS_ERR_X509_INVALID_DATE +
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+
+    return( 0 );
+}
+
+/*
+ * X.509 v2/v3 unique identifier (not parsed)
+ */
+static int x509_get_uid( unsigned char **p,
+                         const unsigned char *end,
+                         mbedtls_x509_buf *uid, int n )
+{
+    int ret;
+
+    if( *p == end )
+        return( 0 );
+
+    uid->tag = **p;
+
+    if( ( ret = mbedtls_asn1_get_tag( p, end, &uid->len,
+            MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | n ) ) != 0 )
+    {
+        if( ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
+            return( 0 );
+
+        return( ret );
+    }
+
+    uid->p = *p;
+    *p += uid->len;
+
+    return( 0 );
+}
+
+static int x509_get_basic_constraints( unsigned char **p,
+                                       const unsigned char *end,
+                                       int *ca_istrue,
+                                       int *max_pathlen )
+{
+    int ret;
+    size_t len;
+
+    /*
+     * BasicConstraints ::= SEQUENCE {
+     *      cA                      BOOLEAN DEFAULT FALSE,
+     *      pathLenConstraint       INTEGER (0..MAX) OPTIONAL }
+     */
+    *ca_istrue = 0; /* DEFAULT FALSE */
+    *max_pathlen = 0; /* endless */
+
+    if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
+            MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
+        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+
+    if( *p == end )
+        return( 0 );
+
+    if( ( ret = mbedtls_asn1_get_bool( p, end, ca_istrue ) ) != 0 )
+    {
+        if( ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
+            ret = mbedtls_asn1_get_int( p, end, ca_istrue );
+
+        if( ret != 0 )
+            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+
+        if( *ca_istrue != 0 )
+            *ca_istrue = 1;
+    }
+
+    if( *p == end )
+        return( 0 );
+
+    if( ( ret = mbedtls_asn1_get_int( p, end, max_pathlen ) ) != 0 )
+        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+
+    if( *p != end )
+        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+
+    (*max_pathlen)++;
+
+    return( 0 );
+}
+
+static int x509_get_ns_cert_type( unsigned char **p,
+                                       const unsigned char *end,
+                                       unsigned char *ns_cert_type)
+{
+    int ret;
+    mbedtls_x509_bitstring bs = { 0, 0, NULL };
+
+    if( ( ret = mbedtls_asn1_get_bitstring( p, end, &bs ) ) != 0 )
+        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+
+    if( bs.len != 1 )
+        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
+                MBEDTLS_ERR_ASN1_INVALID_LENGTH );
+
+    /* Get actual bitstring */
+    *ns_cert_type = *bs.p;
+    return( 0 );
+}
+
+static int x509_get_key_usage( unsigned char **p,
+                               const unsigned char *end,
+                               unsigned int *key_usage)
+{
+    int ret;
+    size_t i;
+    mbedtls_x509_bitstring bs = { 0, 0, NULL };
+
+    if( ( ret = mbedtls_asn1_get_bitstring( p, end, &bs ) ) != 0 )
+        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+
+    if( bs.len < 1 )
+        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
+                MBEDTLS_ERR_ASN1_INVALID_LENGTH );
+
+    /* Get actual bitstring */
+    *key_usage = 0;
+    for( i = 0; i < bs.len && i < sizeof( unsigned int ); i++ )
+    {
+        *key_usage |= (unsigned int) bs.p[i] << (8*i);
+    }
+
+    return( 0 );
+}
+
+/*
+ * ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId
+ *
+ * KeyPurposeId ::= OBJECT IDENTIFIER
+ */
+static int x509_get_ext_key_usage( unsigned char **p,
+                               const unsigned char *end,
+                               mbedtls_x509_sequence *ext_key_usage)
+{
+    int ret;
+
+    if( ( ret = mbedtls_asn1_get_sequence_of( p, end, ext_key_usage, MBEDTLS_ASN1_OID ) ) != 0 )
+        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+
+    /* Sequence length must be >= 1 */
+    if( ext_key_usage->buf.p == NULL )
+        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
+                MBEDTLS_ERR_ASN1_INVALID_LENGTH );
+
+    return( 0 );
+}
+
+/*
+ * SubjectAltName ::= GeneralNames
+ *
+ * GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName
+ *
+ * GeneralName ::= CHOICE {
+ *      otherName                       [0]     OtherName,
+ *      rfc822Name                      [1]     IA5String,
+ *      dNSName                         [2]     IA5String,
+ *      x400Address                     [3]     ORAddress,
+ *      directoryName                   [4]     Name,
+ *      ediPartyName                    [5]     EDIPartyName,
+ *      uniformResourceIdentifier       [6]     IA5String,
+ *      iPAddress                       [7]     OCTET STRING,
+ *      registeredID                    [8]     OBJECT IDENTIFIER }
+ *
+ * OtherName ::= SEQUENCE {
+ *      type-id    OBJECT IDENTIFIER,
+ *      value      [0] EXPLICIT ANY DEFINED BY type-id }
+ *
+ * EDIPartyName ::= SEQUENCE {
+ *      nameAssigner            [0]     DirectoryString OPTIONAL,
+ *      partyName               [1]     DirectoryString }
+ *
+ * NOTE: we only parse and use dNSName at this point.
+ */
+static int x509_get_subject_alt_name( unsigned char **p,
+                                      const unsigned char *end,
+                                      mbedtls_x509_sequence *subject_alt_name )
+{
+    int ret;
+    size_t len, tag_len;
+    mbedtls_asn1_buf *buf;
+    unsigned char tag;
+    mbedtls_asn1_sequence *cur = subject_alt_name;
+
+    /* Get main sequence tag */
+    if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
+            MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
+        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+
+    if( *p + len != end )
+        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+
+    while( *p < end )
+    {
+        if( ( end - *p ) < 1 )
+            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
+                    MBEDTLS_ERR_ASN1_OUT_OF_DATA );
+
+        tag = **p;
+        (*p)++;
+        if( ( ret = mbedtls_asn1_get_len( p, end, &tag_len ) ) != 0 )
+            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+
+        if( ( tag & MBEDTLS_ASN1_TAG_CLASS_MASK ) !=
+                MBEDTLS_ASN1_CONTEXT_SPECIFIC )
+        {
+            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
+                    MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+        }
+
+        /* Skip everything but DNS name */
+        if( tag != ( MBEDTLS_ASN1_CONTEXT_SPECIFIC | 2 ) )
+        {
+            *p += tag_len;
+            continue;
+        }
+
+        /* Allocate and assign next pointer */
+        if( cur->buf.p != NULL )
+        {
+            if( cur->next != NULL )
+                return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS );
+
+            cur->next = mbedtls_calloc( 1, sizeof( mbedtls_asn1_sequence ) );
+
+            if( cur->next == NULL )
+                return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
+                        MBEDTLS_ERR_ASN1_ALLOC_FAILED );
+
+            cur = cur->next;
+        }
+
+        buf = &(cur->buf);
+        buf->tag = tag;
+        buf->p = *p;
+        buf->len = tag_len;
+        *p += buf->len;
+    }
+
+    /* Set final sequence entry's next pointer to NULL */
+    cur->next = NULL;
+
+    if( *p != end )
+        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+
+    return( 0 );
+}
+
+/*
+ * X.509 v3 extensions
+ *
+ */
+static int x509_get_crt_ext( unsigned char **p,
+                             const unsigned char *end,
+                             mbedtls_x509_crt *crt )
+{
+    int ret;
+    size_t len;
+    unsigned char *end_ext_data, *end_ext_octet;
+
+    if( ( ret = mbedtls_x509_get_ext( p, end, &crt->v3_ext, 3 ) ) != 0 )
+    {
+        if( ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
+            return( 0 );
+
+        return( ret );
+    }
+
+    while( *p < end )
+    {
+        /*
+         * Extension  ::=  SEQUENCE  {
+         *      extnID      OBJECT IDENTIFIER,
+         *      critical    BOOLEAN DEFAULT FALSE,
+         *      extnValue   OCTET STRING  }
+         */
+        mbedtls_x509_buf extn_oid = {0, 0, NULL};
+        int is_critical = 0; /* DEFAULT FALSE */
+        int ext_type = 0;
+
+        if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
+                MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
+            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+
+        end_ext_data = *p + len;
+
+        /* Get extension ID */
+        if( ( ret = mbedtls_asn1_get_tag( p, end_ext_data, &extn_oid.len,
+                                          MBEDTLS_ASN1_OID ) ) != 0 )
+            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+
+        extn_oid.tag = MBEDTLS_ASN1_OID;
+        extn_oid.p = *p;
+        *p += extn_oid.len;
+
+        /* Get optional critical */
+        if( ( ret = mbedtls_asn1_get_bool( p, end_ext_data, &is_critical ) ) != 0 &&
+            ( ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) )
+            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+
+        /* Data should be octet string type */
+        if( ( ret = mbedtls_asn1_get_tag( p, end_ext_data, &len,
+                MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
+            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+
+        end_ext_octet = *p + len;
+
+        if( end_ext_octet != end_ext_data )
+            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
+                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+
+        /*
+         * Detect supported extensions
+         */
+        ret = mbedtls_oid_get_x509_ext_type( &extn_oid, &ext_type );
+
+        if( ret != 0 )
+        {
+            /* No parser found, skip extension */
+            *p = end_ext_octet;
+
+#if !defined(MBEDTLS_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION)
+            if( is_critical )
+            {
+                /* Data is marked as critical: fail */
+                return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
+                        MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+            }
+#endif
+            continue;
+        }
+
+        /* Forbid repeated extensions */
+        if( ( crt->ext_types & ext_type ) != 0 )
+            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS );
+
+        crt->ext_types |= ext_type;
+
+        switch( ext_type )
+        {
+        case MBEDTLS_X509_EXT_BASIC_CONSTRAINTS:
+            /* Parse basic constraints */
+            if( ( ret = x509_get_basic_constraints( p, end_ext_octet,
+                    &crt->ca_istrue, &crt->max_pathlen ) ) != 0 )
+                return( ret );
+            break;
+
+        case MBEDTLS_X509_EXT_KEY_USAGE:
+            /* Parse key usage */
+            if( ( ret = x509_get_key_usage( p, end_ext_octet,
+                    &crt->key_usage ) ) != 0 )
+                return( ret );
+            break;
+
+        case MBEDTLS_X509_EXT_EXTENDED_KEY_USAGE:
+            /* Parse extended key usage */
+            if( ( ret = x509_get_ext_key_usage( p, end_ext_octet,
+                    &crt->ext_key_usage ) ) != 0 )
+                return( ret );
+            break;
+
+        case MBEDTLS_X509_EXT_SUBJECT_ALT_NAME:
+            /* Parse subject alt name */
+            if( ( ret = x509_get_subject_alt_name( p, end_ext_octet,
+                    &crt->subject_alt_names ) ) != 0 )
+                return( ret );
+            break;
+
+        case MBEDTLS_X509_EXT_NS_CERT_TYPE:
+            /* Parse netscape certificate type */
+            if( ( ret = x509_get_ns_cert_type( p, end_ext_octet,
+                    &crt->ns_cert_type ) ) != 0 )
+                return( ret );
+            break;
+
+        default:
+            /*
+             * If this is a non-critical extension, which the oid layer
+             * supports, but there isn't an x509 parser for it,
+             * skip the extension.
+             */
+#if !defined(MBEDTLS_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION)
+            if( is_critical )
+                return( MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE );
+            else
+#endif
+                *p = end_ext_octet;
+        }
+    }
+
+    if( *p != end )
+        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+
+    return( 0 );
+}
+
+/*
+ * Parse and fill a single X.509 certificate in DER format
+ */
+static int x509_crt_parse_der_core( mbedtls_x509_crt *crt,
+                                    const unsigned char *buf,
+                                    size_t buflen,
+                                    int make_copy )
+{
+    int ret;
+    size_t len;
+    unsigned char *p, *end, *crt_end;
+    mbedtls_x509_buf sig_params1, sig_params2, sig_oid2;
+
+    memset( &sig_params1, 0, sizeof( mbedtls_x509_buf ) );
+    memset( &sig_params2, 0, sizeof( mbedtls_x509_buf ) );
+    memset( &sig_oid2, 0, sizeof( mbedtls_x509_buf ) );
+
+    /*
+     * Check for valid input
+     */
+    if( crt == NULL || buf == NULL )
+        return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
+
+    /* Use the original buffer until we figure out actual length. */
+    p = (unsigned char*) buf;
+    len = buflen;
+    end = p + len;
+
+    /*
+     * Certificate  ::=  SEQUENCE  {
+     *      tbsCertificate       TBSCertificate,
+     *      signatureAlgorithm   AlgorithmIdentifier,
+     *      signatureValue       BIT STRING  }
+     */
+    if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
+            MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( MBEDTLS_ERR_X509_INVALID_FORMAT );
+    }
+
+    end = crt_end = p + len;
+    crt->raw.len = crt_end - buf;
+    if( make_copy != 0 )
+    {
+        /* Create and populate a new buffer for the raw field. */
+        crt->raw.p = p = mbedtls_calloc( 1, crt->raw.len );
+        if( crt->raw.p == NULL )
+            return( MBEDTLS_ERR_X509_ALLOC_FAILED );
+
+        memcpy( crt->raw.p, buf, crt->raw.len );
+        crt->own_buffer = 1;
+
+        p += crt->raw.len - len;
+        end = crt_end = p + len;
+    }
+    else
+    {
+        crt->raw.p = (unsigned char*) buf;
+        crt->own_buffer = 0;
+    }
+
+    /*
+     * TBSCertificate  ::=  SEQUENCE  {
+     */
+    crt->tbs.p = p;
+
+    if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
+            MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
+    }
+
+    end = p + len;
+    crt->tbs.len = end - crt->tbs.p;
+
+    /*
+     * Version  ::=  INTEGER  {  v1(0), v2(1), v3(2)  }
+     *
+     * CertificateSerialNumber  ::=  INTEGER
+     *
+     * signature            AlgorithmIdentifier
+     */
+    if( ( ret = x509_get_version(  &p, end, &crt->version  ) ) != 0 ||
+        ( ret = mbedtls_x509_get_serial(   &p, end, &crt->serial   ) ) != 0 ||
+        ( ret = mbedtls_x509_get_alg(      &p, end, &crt->sig_oid,
+                                            &sig_params1 ) ) != 0 )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( ret );
+    }
+
+    if( crt->version < 0 || crt->version > 2 )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( MBEDTLS_ERR_X509_UNKNOWN_VERSION );
+    }
+
+    crt->version++;
+
+    if( ( ret = mbedtls_x509_get_sig_alg( &crt->sig_oid, &sig_params1,
+                                  &crt->sig_md, &crt->sig_pk,
+                                  &crt->sig_opts ) ) != 0 )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( ret );
+    }
+
+    /*
+     * issuer               Name
+     */
+    crt->issuer_raw.p = p;
+
+    if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
+            MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
+    }
+
+    if( ( ret = mbedtls_x509_get_name( &p, p + len, &crt->issuer ) ) != 0 )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( ret );
+    }
+
+    crt->issuer_raw.len = p - crt->issuer_raw.p;
+
+    /*
+     * Validity ::= SEQUENCE {
+     *      notBefore      Time,
+     *      notAfter       Time }
+     *
+     */
+    if( ( ret = x509_get_dates( &p, end, &crt->valid_from,
+                                         &crt->valid_to ) ) != 0 )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( ret );
+    }
+
+    /*
+     * subject              Name
+     */
+    crt->subject_raw.p = p;
+
+    if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
+            MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
+    }
+
+    if( len && ( ret = mbedtls_x509_get_name( &p, p + len, &crt->subject ) ) != 0 )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( ret );
+    }
+
+    crt->subject_raw.len = p - crt->subject_raw.p;
+
+    /*
+     * SubjectPublicKeyInfo
+     */
+    crt->pk_raw.p = p;
+    if( ( ret = mbedtls_pk_parse_subpubkey( &p, end, &crt->pk ) ) != 0 )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( ret );
+    }
+    crt->pk_raw.len = p - crt->pk_raw.p;
+
+    /*
+     *  issuerUniqueID  [1]  IMPLICIT UniqueIdentifier OPTIONAL,
+     *                       -- If present, version shall be v2 or v3
+     *  subjectUniqueID [2]  IMPLICIT UniqueIdentifier OPTIONAL,
+     *                       -- If present, version shall be v2 or v3
+     *  extensions      [3]  EXPLICIT Extensions OPTIONAL
+     *                       -- If present, version shall be v3
+     */
+    if( crt->version == 2 || crt->version == 3 )
+    {
+        ret = x509_get_uid( &p, end, &crt->issuer_id,  1 );
+        if( ret != 0 )
+        {
+            mbedtls_x509_crt_free( crt );
+            return( ret );
+        }
+    }
+
+    if( crt->version == 2 || crt->version == 3 )
+    {
+        ret = x509_get_uid( &p, end, &crt->subject_id,  2 );
+        if( ret != 0 )
+        {
+            mbedtls_x509_crt_free( crt );
+            return( ret );
+        }
+    }
+
+#if !defined(MBEDTLS_X509_ALLOW_EXTENSIONS_NON_V3)
+    if( crt->version == 3 )
+#endif
+    {
+        ret = x509_get_crt_ext( &p, end, crt );
+        if( ret != 0 )
+        {
+            mbedtls_x509_crt_free( crt );
+            return( ret );
+        }
+    }
+
+    if( p != end )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( MBEDTLS_ERR_X509_INVALID_FORMAT +
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+    }
+
+    end = crt_end;
+
+    /*
+     *  }
+     *  -- end of TBSCertificate
+     *
+     *  signatureAlgorithm   AlgorithmIdentifier,
+     *  signatureValue       BIT STRING
+     */
+    if( ( ret = mbedtls_x509_get_alg( &p, end, &sig_oid2, &sig_params2 ) ) != 0 )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( ret );
+    }
+
+    if( crt->sig_oid.len != sig_oid2.len ||
+        memcmp( crt->sig_oid.p, sig_oid2.p, crt->sig_oid.len ) != 0 ||
+        sig_params1.len != sig_params2.len ||
+        ( sig_params1.len != 0 &&
+          memcmp( sig_params1.p, sig_params2.p, sig_params1.len ) != 0 ) )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( MBEDTLS_ERR_X509_SIG_MISMATCH );
+    }
+
+    if( ( ret = mbedtls_x509_get_sig( &p, end, &crt->sig ) ) != 0 )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( ret );
+    }
+
+    if( p != end )
+    {
+        mbedtls_x509_crt_free( crt );
+        return( MBEDTLS_ERR_X509_INVALID_FORMAT +
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+    }
+
+    return( 0 );
+}
+
+/*
+ * Parse one X.509 certificate in DER format from a buffer and add them to a
+ * chained list
+ */
+static int mbedtls_x509_crt_parse_der_internal( mbedtls_x509_crt *chain,
+                                                const unsigned char *buf,
+                                                size_t buflen,
+                                                int make_copy )
+{
+    int ret;
+    mbedtls_x509_crt *crt = chain, *prev = NULL;
+
+    /*
+     * Check for valid input
+     */
+    if( crt == NULL || buf == NULL )
+        return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
+
+    while( crt->version != 0 && crt->next != NULL )
+    {
+        prev = crt;
+        crt = crt->next;
+    }
+
+    /*
+     * Add new certificate on the end of the chain if needed.
+     */
+    if( crt->version != 0 && crt->next == NULL )
+    {
+        crt->next = mbedtls_calloc( 1, sizeof( mbedtls_x509_crt ) );
+
+        if( crt->next == NULL )
+            return( MBEDTLS_ERR_X509_ALLOC_FAILED );
+
+        prev = crt;
+        mbedtls_x509_crt_init( crt->next );
+        crt = crt->next;
+    }
+
+    if( ( ret = x509_crt_parse_der_core( crt, buf, buflen, make_copy ) ) != 0 )
+    {
+        if( prev )
+            prev->next = NULL;
+
+        if( crt != chain )
+            mbedtls_free( crt );
+
+        return( ret );
+    }
+
+    return( 0 );
+}
+
+int mbedtls_x509_crt_parse_der_nocopy( mbedtls_x509_crt *chain,
+                                       const unsigned char *buf,
+                                       size_t buflen )
+{
+    return( mbedtls_x509_crt_parse_der_internal( chain, buf, buflen, 0 ) );
+}
+
+int mbedtls_x509_crt_parse_der( mbedtls_x509_crt *chain,
+                                const unsigned char *buf,
+                                size_t buflen )
+{
+    return( mbedtls_x509_crt_parse_der_internal( chain, buf, buflen, 1 ) );
+}
+
+/*
+ * Parse one or more PEM certificates from a buffer and add them to the chained
+ * list
+ */
+int mbedtls_x509_crt_parse( mbedtls_x509_crt *chain,
+                            const unsigned char *buf,
+                            size_t buflen )
+{
+#if defined(MBEDTLS_PEM_PARSE_C)
+    int success = 0, first_error = 0, total_failed = 0;
+    int buf_format = MBEDTLS_X509_FORMAT_DER;
+#endif
+
+    /*
+     * Check for valid input
+     */
+    if( chain == NULL || buf == NULL )
+        return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
+
+    /*
+     * Determine buffer content. Buffer contains either one DER certificate or
+     * one or more PEM certificates.
+     */
+#if defined(MBEDTLS_PEM_PARSE_C)
+    if( buflen != 0 && buf[buflen - 1] == '\0' &&
+        strstr( (const char *) buf, "-----BEGIN CERTIFICATE-----" ) != NULL )
+    {
+        buf_format = MBEDTLS_X509_FORMAT_PEM;
+    }
+
+    if( buf_format == MBEDTLS_X509_FORMAT_DER )
+        return mbedtls_x509_crt_parse_der( chain, buf, buflen );
+#else
+    return mbedtls_x509_crt_parse_der( chain, buf, buflen );
+#endif
+
+#if defined(MBEDTLS_PEM_PARSE_C)
+    if( buf_format == MBEDTLS_X509_FORMAT_PEM )
+    {
+        int ret;
+        mbedtls_pem_context pem;
+
+        /* 1 rather than 0 since the terminating NULL byte is counted in */
+        while( buflen > 1 )
+        {
+            size_t use_len;
+            mbedtls_pem_init( &pem );
+
+            /* If we get there, we know the string is null-terminated */
+            ret = mbedtls_pem_read_buffer( &pem,
+                           "-----BEGIN CERTIFICATE-----",
+                           "-----END CERTIFICATE-----",
+                           buf, NULL, 0, &use_len );
+
+            if( ret == 0 )
+            {
+                /*
+                 * Was PEM encoded
+                 */
+                buflen -= use_len;
+                buf += use_len;
+            }
+            else if( ret == MBEDTLS_ERR_PEM_BAD_INPUT_DATA )
+            {
+                return( ret );
+            }
+            else if( ret != MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT )
+            {
+                mbedtls_pem_free( &pem );
+
+                /*
+                 * PEM header and footer were found
+                 */
+                buflen -= use_len;
+                buf += use_len;
+
+                if( first_error == 0 )
+                    first_error = ret;
+
+                total_failed++;
+                continue;
+            }
+            else
+                break;
+
+            ret = mbedtls_x509_crt_parse_der( chain, pem.buf, pem.buflen );
+
+            mbedtls_pem_free( &pem );
+
+            if( ret != 0 )
+            {
+                /*
+                 * Quit parsing on a memory error
+                 */
+                if( ret == MBEDTLS_ERR_X509_ALLOC_FAILED )
+                    return( ret );
+
+                if( first_error == 0 )
+                    first_error = ret;
+
+                total_failed++;
+                continue;
+            }
+
+            success = 1;
+        }
+    }
+
+    if( success )
+        return( total_failed );
+    else if( first_error )
+        return( first_error );
+    else
+        return( MBEDTLS_ERR_X509_CERT_UNKNOWN_FORMAT );
+#endif /* MBEDTLS_PEM_PARSE_C */
+}
+
+#if defined(MBEDTLS_FS_IO)
+/*
+ * Load one or more certificates and add them to the chained list
+ */
+int mbedtls_x509_crt_parse_file( mbedtls_x509_crt *chain, const char *path )
+{
+    int ret;
+    size_t n;
+    unsigned char *buf;
+
+    if( ( ret = mbedtls_pk_load_file( path, &buf, &n ) ) != 0 )
+        return( ret );
+
+    ret = mbedtls_x509_crt_parse( chain, buf, n );
+
+    mbedtls_platform_zeroize( buf, n );
+    mbedtls_free( buf );
+
+    return( ret );
+}
+
+int mbedtls_x509_crt_parse_path( mbedtls_x509_crt *chain, const char *path )
+{
+    int ret = 0;
+#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
+    int w_ret;
+    WCHAR szDir[MAX_PATH];
+    char filename[MAX_PATH];
+    char *p;
+    size_t len = strlen( path );
+
+    WIN32_FIND_DATAW file_data;
+    HANDLE hFind;
+
+    if( len > MAX_PATH - 3 )
+        return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
+
+    memset( szDir, 0, sizeof(szDir) );
+    memset( filename, 0, MAX_PATH );
+    memcpy( filename, path, len );
+    filename[len++] = '\\';
+    p = filename + len;
+    filename[len++] = '*';
+
+    w_ret = MultiByteToWideChar( CP_ACP, 0, filename, (int)len, szDir,
+                                 MAX_PATH - 3 );
+    if( w_ret == 0 )
+        return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
+
+    hFind = FindFirstFileW( szDir, &file_data );
+    if( hFind == INVALID_HANDLE_VALUE )
+        return( MBEDTLS_ERR_X509_FILE_IO_ERROR );
+
+    len = MAX_PATH - len;
+    do
+    {
+        memset( p, 0, len );
+
+        if( file_data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY )
+            continue;
+
+        w_ret = WideCharToMultiByte( CP_ACP, 0, file_data.cFileName,
+                                     lstrlenW( file_data.cFileName ),
+                                     p, (int) len - 1,
+                                     NULL, NULL );
+        if( w_ret == 0 )
+        {
+            ret = MBEDTLS_ERR_X509_FILE_IO_ERROR;
+            goto cleanup;
+        }
+
+        w_ret = mbedtls_x509_crt_parse_file( chain, filename );
+        if( w_ret < 0 )
+            ret++;
+        else
+            ret += w_ret;
+    }
+    while( FindNextFileW( hFind, &file_data ) != 0 );
+
+    if( GetLastError() != ERROR_NO_MORE_FILES )
+        ret = MBEDTLS_ERR_X509_FILE_IO_ERROR;
+
+cleanup:
+    FindClose( hFind );
+#else /* _WIN32 */
+    int t_ret;
+    int snp_ret;
+    struct stat sb;
+    struct dirent *entry;
+    char entry_name[MBEDTLS_X509_MAX_FILE_PATH_LEN];
+    DIR *dir = opendir( path );
+
+    if( dir == NULL )
+        return( MBEDTLS_ERR_X509_FILE_IO_ERROR );
+
+#if defined(MBEDTLS_THREADING_C)
+    if( ( ret = mbedtls_mutex_lock( &mbedtls_threading_readdir_mutex ) ) != 0 )
+    {
+        closedir( dir );
+        return( ret );
+    }
+#endif /* MBEDTLS_THREADING_C */
+
+    while( ( entry = readdir( dir ) ) != NULL )
+    {
+        snp_ret = mbedtls_snprintf( entry_name, sizeof entry_name,
+                                    "%s/%s", path, entry->d_name );
+
+        if( snp_ret < 0 || (size_t)snp_ret >= sizeof entry_name )
+        {
+            ret = MBEDTLS_ERR_X509_BUFFER_TOO_SMALL;
+            goto cleanup;
+        }
+        else if( stat( entry_name, &sb ) == -1 )
+        {
+            ret = MBEDTLS_ERR_X509_FILE_IO_ERROR;
+            goto cleanup;
+        }
+
+        if( !S_ISREG( sb.st_mode ) )
+            continue;
+
+        // Ignore parse errors
+        //
+        t_ret = mbedtls_x509_crt_parse_file( chain, entry_name );
+        if( t_ret < 0 )
+            ret++;
+        else
+            ret += t_ret;
+    }
+
+cleanup:
+    closedir( dir );
+
+#if defined(MBEDTLS_THREADING_C)
+    if( mbedtls_mutex_unlock( &mbedtls_threading_readdir_mutex ) != 0 )
+        ret = MBEDTLS_ERR_THREADING_MUTEX_ERROR;
+#endif /* MBEDTLS_THREADING_C */
+
+#endif /* _WIN32 */
+
+    return( ret );
+}
+#endif /* MBEDTLS_FS_IO */
+
+static int x509_info_subject_alt_name( char **buf, size_t *size,
+                                       const mbedtls_x509_sequence *subject_alt_name )
+{
+    size_t i;
+    size_t n = *size;
+    char *p = *buf;
+    const mbedtls_x509_sequence *cur = subject_alt_name;
+    const char *sep = "";
+    size_t sep_len = 0;
+
+    while( cur != NULL )
+    {
+        if( cur->buf.len + sep_len >= n )
+        {
+            *p = '\0';
+            return( MBEDTLS_ERR_X509_BUFFER_TOO_SMALL );
+        }
+
+        n -= cur->buf.len + sep_len;
+        for( i = 0; i < sep_len; i++ )
+            *p++ = sep[i];
+        for( i = 0; i < cur->buf.len; i++ )
+            *p++ = cur->buf.p[i];
+
+        sep = ", ";
+        sep_len = 2;
+
+        cur = cur->next;
+    }
+
+    *p = '\0';
+
+    *size = n;
+    *buf = p;
+
+    return( 0 );
+}
+
+#define PRINT_ITEM(i)                           \
+    {                                           \
+        ret = mbedtls_snprintf( p, n, "%s" i, sep );    \
+        MBEDTLS_X509_SAFE_SNPRINTF;                        \
+        sep = ", ";                             \
+    }
+
+#define CERT_TYPE(type,name)                    \
+    if( ns_cert_type & type )                   \
+        PRINT_ITEM( name );
+
+static int x509_info_cert_type( char **buf, size_t *size,
+                                unsigned char ns_cert_type )
+{
+    int ret;
+    size_t n = *size;
+    char *p = *buf;
+    const char *sep = "";
+
+    CERT_TYPE( MBEDTLS_X509_NS_CERT_TYPE_SSL_CLIENT,         "SSL Client" );
+    CERT_TYPE( MBEDTLS_X509_NS_CERT_TYPE_SSL_SERVER,         "SSL Server" );
+    CERT_TYPE( MBEDTLS_X509_NS_CERT_TYPE_EMAIL,              "Email" );
+    CERT_TYPE( MBEDTLS_X509_NS_CERT_TYPE_OBJECT_SIGNING,     "Object Signing" );
+    CERT_TYPE( MBEDTLS_X509_NS_CERT_TYPE_RESERVED,           "Reserved" );
+    CERT_TYPE( MBEDTLS_X509_NS_CERT_TYPE_SSL_CA,             "SSL CA" );
+    CERT_TYPE( MBEDTLS_X509_NS_CERT_TYPE_EMAIL_CA,           "Email CA" );
+    CERT_TYPE( MBEDTLS_X509_NS_CERT_TYPE_OBJECT_SIGNING_CA,  "Object Signing CA" );
+
+    *size = n;
+    *buf = p;
+
+    return( 0 );
+}
+
+#define KEY_USAGE(code,name)    \
+    if( key_usage & code )      \
+        PRINT_ITEM( name );
+
+static int x509_info_key_usage( char **buf, size_t *size,
+                                unsigned int key_usage )
+{
+    int ret;
+    size_t n = *size;
+    char *p = *buf;
+    const char *sep = "";
+
+    KEY_USAGE( MBEDTLS_X509_KU_DIGITAL_SIGNATURE,    "Digital Signature" );
+    KEY_USAGE( MBEDTLS_X509_KU_NON_REPUDIATION,      "Non Repudiation" );
+    KEY_USAGE( MBEDTLS_X509_KU_KEY_ENCIPHERMENT,     "Key Encipherment" );
+    KEY_USAGE( MBEDTLS_X509_KU_DATA_ENCIPHERMENT,    "Data Encipherment" );
+    KEY_USAGE( MBEDTLS_X509_KU_KEY_AGREEMENT,        "Key Agreement" );
+    KEY_USAGE( MBEDTLS_X509_KU_KEY_CERT_SIGN,        "Key Cert Sign" );
+    KEY_USAGE( MBEDTLS_X509_KU_CRL_SIGN,             "CRL Sign" );
+    KEY_USAGE( MBEDTLS_X509_KU_ENCIPHER_ONLY,        "Encipher Only" );
+    KEY_USAGE( MBEDTLS_X509_KU_DECIPHER_ONLY,        "Decipher Only" );
+
+    *size = n;
+    *buf = p;
+
+    return( 0 );
+}
+
+static int x509_info_ext_key_usage( char **buf, size_t *size,
+                                    const mbedtls_x509_sequence *extended_key_usage )
+{
+    int ret;
+    const char *desc;
+    size_t n = *size;
+    char *p = *buf;
+    const mbedtls_x509_sequence *cur = extended_key_usage;
+    const char *sep = "";
+
+    while( cur != NULL )
+    {
+        if( mbedtls_oid_get_extended_key_usage( &cur->buf, &desc ) != 0 )
+            desc = "???";
+
+        ret = mbedtls_snprintf( p, n, "%s%s", sep, desc );
+        MBEDTLS_X509_SAFE_SNPRINTF;
+
+        sep = ", ";
+
+        cur = cur->next;
+    }
+
+    *size = n;
+    *buf = p;
+
+    return( 0 );
+}
+
+/*
+ * Return an informational string about the certificate.
+ */
+#define BEFORE_COLON    18
+#define BC              "18"
+int mbedtls_x509_crt_info( char *buf, size_t size, const char *prefix,
+                   const mbedtls_x509_crt *crt )
+{
+    int ret;
+    size_t n;
+    char *p;
+    char key_size_str[BEFORE_COLON];
+
+    p = buf;
+    n = size;
+
+    if( NULL == crt )
+    {
+        ret = mbedtls_snprintf( p, n, "\nCertificate is uninitialised!\n" );
+        MBEDTLS_X509_SAFE_SNPRINTF;
+
+        return( (int) ( size - n ) );
+    }
+
+    ret = mbedtls_snprintf( p, n, "%scert. version     : %d\n",
+                               prefix, crt->version );
+    MBEDTLS_X509_SAFE_SNPRINTF;
+    ret = mbedtls_snprintf( p, n, "%sserial number     : ",
+                               prefix );
+    MBEDTLS_X509_SAFE_SNPRINTF;
+
+    ret = mbedtls_x509_serial_gets( p, n, &crt->serial );
+    MBEDTLS_X509_SAFE_SNPRINTF;
+
+    ret = mbedtls_snprintf( p, n, "\n%sissuer name       : ", prefix );
+    MBEDTLS_X509_SAFE_SNPRINTF;
+    ret = mbedtls_x509_dn_gets( p, n, &crt->issuer  );
+    MBEDTLS_X509_SAFE_SNPRINTF;
+
+    ret = mbedtls_snprintf( p, n, "\n%ssubject name      : ", prefix );
+    MBEDTLS_X509_SAFE_SNPRINTF;
+    ret = mbedtls_x509_dn_gets( p, n, &crt->subject );
+    MBEDTLS_X509_SAFE_SNPRINTF;
+
+    ret = mbedtls_snprintf( p, n, "\n%sissued  on        : " \
+                   "%04d-%02d-%02d %02d:%02d:%02d", prefix,
+                   crt->valid_from.year, crt->valid_from.mon,
+                   crt->valid_from.day,  crt->valid_from.hour,
+                   crt->valid_from.min,  crt->valid_from.sec );
+    MBEDTLS_X509_SAFE_SNPRINTF;
+
+    ret = mbedtls_snprintf( p, n, "\n%sexpires on        : " \
+                   "%04d-%02d-%02d %02d:%02d:%02d", prefix,
+                   crt->valid_to.year, crt->valid_to.mon,
+                   crt->valid_to.day,  crt->valid_to.hour,
+                   crt->valid_to.min,  crt->valid_to.sec );
+    MBEDTLS_X509_SAFE_SNPRINTF;
+
+    ret = mbedtls_snprintf( p, n, "\n%ssigned using      : ", prefix );
+    MBEDTLS_X509_SAFE_SNPRINTF;
+
+    ret = mbedtls_x509_sig_alg_gets( p, n, &crt->sig_oid, crt->sig_pk,
+                             crt->sig_md, crt->sig_opts );
+    MBEDTLS_X509_SAFE_SNPRINTF;
+
+    /* Key size */
+    if( ( ret = mbedtls_x509_key_size_helper( key_size_str, BEFORE_COLON,
+                                      mbedtls_pk_get_name( &crt->pk ) ) ) != 0 )
+    {
+        return( ret );
+    }
+
+    ret = mbedtls_snprintf( p, n, "\n%s%-" BC "s: %d bits", prefix, key_size_str,
+                          (int) mbedtls_pk_get_bitlen( &crt->pk ) );
+    MBEDTLS_X509_SAFE_SNPRINTF;
+
+    /*
+     * Optional extensions
+     */
+
+    if( crt->ext_types & MBEDTLS_X509_EXT_BASIC_CONSTRAINTS )
+    {
+        ret = mbedtls_snprintf( p, n, "\n%sbasic constraints : CA=%s", prefix,
+                        crt->ca_istrue ? "true" : "false" );
+        MBEDTLS_X509_SAFE_SNPRINTF;
+
+        if( crt->max_pathlen > 0 )
+        {
+            ret = mbedtls_snprintf( p, n, ", max_pathlen=%d", crt->max_pathlen - 1 );
+            MBEDTLS_X509_SAFE_SNPRINTF;
+        }
+    }
+
+    if( crt->ext_types & MBEDTLS_X509_EXT_SUBJECT_ALT_NAME )
+    {
+        ret = mbedtls_snprintf( p, n, "\n%ssubject alt name  : ", prefix );
+        MBEDTLS_X509_SAFE_SNPRINTF;
+
+        if( ( ret = x509_info_subject_alt_name( &p, &n,
+                                            &crt->subject_alt_names ) ) != 0 )
+            return( ret );
+    }
+
+    if( crt->ext_types & MBEDTLS_X509_EXT_NS_CERT_TYPE )
+    {
+        ret = mbedtls_snprintf( p, n, "\n%scert. type        : ", prefix );
+        MBEDTLS_X509_SAFE_SNPRINTF;
+
+        if( ( ret = x509_info_cert_type( &p, &n, crt->ns_cert_type ) ) != 0 )
+            return( ret );
+    }
+
+    if( crt->ext_types & MBEDTLS_X509_EXT_KEY_USAGE )
+    {
+        ret = mbedtls_snprintf( p, n, "\n%skey usage         : ", prefix );
+        MBEDTLS_X509_SAFE_SNPRINTF;
+
+        if( ( ret = x509_info_key_usage( &p, &n, crt->key_usage ) ) != 0 )
+            return( ret );
+    }
+
+    if( crt->ext_types & MBEDTLS_X509_EXT_EXTENDED_KEY_USAGE )
+    {
+        ret = mbedtls_snprintf( p, n, "\n%sext key usage     : ", prefix );
+        MBEDTLS_X509_SAFE_SNPRINTF;
+
+        if( ( ret = x509_info_ext_key_usage( &p, &n,
+                                             &crt->ext_key_usage ) ) != 0 )
+            return( ret );
+    }
+
+    ret = mbedtls_snprintf( p, n, "\n" );
+    MBEDTLS_X509_SAFE_SNPRINTF;
+
+    return( (int) ( size - n ) );
+}
+
+struct x509_crt_verify_string {
+    int code;
+    const char *string;
+};
+
+static const struct x509_crt_verify_string x509_crt_verify_strings[] = {
+    { MBEDTLS_X509_BADCERT_EXPIRED,       "The certificate validity has expired" },
+    { MBEDTLS_X509_BADCERT_REVOKED,       "The certificate has been revoked (is on a CRL)" },
+    { MBEDTLS_X509_BADCERT_CN_MISMATCH,   "The certificate Common Name (CN) does not match with the expected CN" },
+    { MBEDTLS_X509_BADCERT_NOT_TRUSTED,   "The certificate is not correctly signed by the trusted CA" },
+    { MBEDTLS_X509_BADCRL_NOT_TRUSTED,    "The CRL is not correctly signed by the trusted CA" },
+    { MBEDTLS_X509_BADCRL_EXPIRED,        "The CRL is expired" },
+    { MBEDTLS_X509_BADCERT_MISSING,       "Certificate was missing" },
+    { MBEDTLS_X509_BADCERT_SKIP_VERIFY,   "Certificate verification was skipped" },
+    { MBEDTLS_X509_BADCERT_OTHER,         "Other reason (can be used by verify callback)" },
+    { MBEDTLS_X509_BADCERT_FUTURE,        "The certificate validity starts in the future" },
+    { MBEDTLS_X509_BADCRL_FUTURE,         "The CRL is from the future" },
+    { MBEDTLS_X509_BADCERT_KEY_USAGE,     "Usage does not match the keyUsage extension" },
+    { MBEDTLS_X509_BADCERT_EXT_KEY_USAGE, "Usage does not match the extendedKeyUsage extension" },
+    { MBEDTLS_X509_BADCERT_NS_CERT_TYPE,  "Usage does not match the nsCertType extension" },
+    { MBEDTLS_X509_BADCERT_BAD_MD,        "The certificate is signed with an unacceptable hash." },
+    { MBEDTLS_X509_BADCERT_BAD_PK,        "The certificate is signed with an unacceptable PK alg (eg RSA vs ECDSA)." },
+    { MBEDTLS_X509_BADCERT_BAD_KEY,       "The certificate is signed with an unacceptable key (eg bad curve, RSA too short)." },
+    { MBEDTLS_X509_BADCRL_BAD_MD,         "The CRL is signed with an unacceptable hash." },
+    { MBEDTLS_X509_BADCRL_BAD_PK,         "The CRL is signed with an unacceptable PK alg (eg RSA vs ECDSA)." },
+    { MBEDTLS_X509_BADCRL_BAD_KEY,        "The CRL is signed with an unacceptable key (eg bad curve, RSA too short)." },
+    { 0, NULL }
+};
+
+int mbedtls_x509_crt_verify_info( char *buf, size_t size, const char *prefix,
+                          uint32_t flags )
+{
+    int ret;
+    const struct x509_crt_verify_string *cur;
+    char *p = buf;
+    size_t n = size;
+
+    for( cur = x509_crt_verify_strings; cur->string != NULL ; cur++ )
+    {
+        if( ( flags & cur->code ) == 0 )
+            continue;
+
+        ret = mbedtls_snprintf( p, n, "%s%s\n", prefix, cur->string );
+        MBEDTLS_X509_SAFE_SNPRINTF;
+        flags ^= cur->code;
+    }
+
+    if( flags != 0 )
+    {
+        ret = mbedtls_snprintf( p, n, "%sUnknown reason "
+                                       "(this should not happen)\n", prefix );
+        MBEDTLS_X509_SAFE_SNPRINTF;
+    }
+
+    return( (int) ( size - n ) );
+}
+
+#if defined(MBEDTLS_X509_CHECK_KEY_USAGE)
+int mbedtls_x509_crt_check_key_usage( const mbedtls_x509_crt *crt,
+                                      unsigned int usage )
+{
+    unsigned int usage_must, usage_may;
+    unsigned int may_mask = MBEDTLS_X509_KU_ENCIPHER_ONLY
+                          | MBEDTLS_X509_KU_DECIPHER_ONLY;
+
+    if( ( crt->ext_types & MBEDTLS_X509_EXT_KEY_USAGE ) == 0 )
+        return( 0 );
+
+    usage_must = usage & ~may_mask;
+
+    if( ( ( crt->key_usage & ~may_mask ) & usage_must ) != usage_must )
+        return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
+
+    usage_may = usage & may_mask;
+
+    if( ( ( crt->key_usage & may_mask ) | usage_may ) != usage_may )
+        return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
+
+    return( 0 );
+}
+#endif
+
+#if defined(MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE)
+int mbedtls_x509_crt_check_extended_key_usage( const mbedtls_x509_crt *crt,
+                                       const char *usage_oid,
+                                       size_t usage_len )
+{
+    const mbedtls_x509_sequence *cur;
+
+    /* Extension is not mandatory, absent means no restriction */
+    if( ( crt->ext_types & MBEDTLS_X509_EXT_EXTENDED_KEY_USAGE ) == 0 )
+        return( 0 );
+
+    /*
+     * Look for the requested usage (or wildcard ANY) in our list
+     */
+    for( cur = &crt->ext_key_usage; cur != NULL; cur = cur->next )
+    {
+        const mbedtls_x509_buf *cur_oid = &cur->buf;
+
+        if( cur_oid->len == usage_len &&
+            memcmp( cur_oid->p, usage_oid, usage_len ) == 0 )
+        {
+            return( 0 );
+        }
+
+        if( MBEDTLS_OID_CMP( MBEDTLS_OID_ANY_EXTENDED_KEY_USAGE, cur_oid ) == 0 )
+            return( 0 );
+    }
+
+    return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
+}
+#endif /* MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE */
+
+#if defined(MBEDTLS_X509_CRL_PARSE_C)
+/*
+ * Return 1 if the certificate is revoked, or 0 otherwise.
+ */
+int mbedtls_x509_crt_is_revoked( const mbedtls_x509_crt *crt, const mbedtls_x509_crl *crl )
+{
+    const mbedtls_x509_crl_entry *cur = &crl->entry;
+
+    while( cur != NULL && cur->serial.len != 0 )
+    {
+        if( crt->serial.len == cur->serial.len &&
+            memcmp( crt->serial.p, cur->serial.p, crt->serial.len ) == 0 )
+        {
+            if( mbedtls_x509_time_is_past( &cur->revocation_date ) )
+                return( 1 );
+        }
+
+        cur = cur->next;
+    }
+
+    return( 0 );
+}
+
+/*
+ * Check that the given certificate is not revoked according to the CRL.
+ * Skip validation if no CRL for the given CA is present.
+ */
+static int x509_crt_verifycrl( mbedtls_x509_crt *crt, mbedtls_x509_crt *ca,
+                               mbedtls_x509_crl *crl_list,
+                               const mbedtls_x509_crt_profile *profile )
+{
+    int flags = 0;
+    unsigned char hash[MBEDTLS_MD_MAX_SIZE];
+    const mbedtls_md_info_t *md_info;
+
+    if( ca == NULL )
+        return( flags );
+
+    while( crl_list != NULL )
+    {
+        if( crl_list->version == 0 ||
+            x509_name_cmp( &crl_list->issuer, &ca->subject ) != 0 )
+        {
+            crl_list = crl_list->next;
+            continue;
+        }
+
+        /*
+         * Check if the CA is configured to sign CRLs
+         */
+#if defined(MBEDTLS_X509_CHECK_KEY_USAGE)
+        if( mbedtls_x509_crt_check_key_usage( ca,
+                                              MBEDTLS_X509_KU_CRL_SIGN ) != 0 )
+        {
+            flags |= MBEDTLS_X509_BADCRL_NOT_TRUSTED;
+            break;
+        }
+#endif
+
+        /*
+         * Check if CRL is correctly signed by the trusted CA
+         */
+        if( x509_profile_check_md_alg( profile, crl_list->sig_md ) != 0 )
+            flags |= MBEDTLS_X509_BADCRL_BAD_MD;
+
+        if( x509_profile_check_pk_alg( profile, crl_list->sig_pk ) != 0 )
+            flags |= MBEDTLS_X509_BADCRL_BAD_PK;
+
+        md_info = mbedtls_md_info_from_type( crl_list->sig_md );
+        if( mbedtls_md( md_info, crl_list->tbs.p, crl_list->tbs.len, hash ) != 0 )
+        {
+            /* Note: this can't happen except after an internal error */
+            flags |= MBEDTLS_X509_BADCRL_NOT_TRUSTED;
+            break;
+        }
+
+        if( x509_profile_check_key( profile, &ca->pk ) != 0 )
+            flags |= MBEDTLS_X509_BADCERT_BAD_KEY;
+
+        if( mbedtls_pk_verify_ext( crl_list->sig_pk, crl_list->sig_opts, &ca->pk,
+                           crl_list->sig_md, hash, mbedtls_md_get_size( md_info ),
+                           crl_list->sig.p, crl_list->sig.len ) != 0 )
+        {
+            flags |= MBEDTLS_X509_BADCRL_NOT_TRUSTED;
+            break;
+        }
+
+        /*
+         * Check for validity of CRL (Do not drop out)
+         */
+        if( mbedtls_x509_time_is_past( &crl_list->next_update ) )
+            flags |= MBEDTLS_X509_BADCRL_EXPIRED;
+
+        if( mbedtls_x509_time_is_future( &crl_list->this_update ) )
+            flags |= MBEDTLS_X509_BADCRL_FUTURE;
+
+        /*
+         * Check if certificate is revoked
+         */
+        if( mbedtls_x509_crt_is_revoked( crt, crl_list ) )
+        {
+            flags |= MBEDTLS_X509_BADCERT_REVOKED;
+            break;
+        }
+
+        crl_list = crl_list->next;
+    }
+
+    return( flags );
+}
+#endif /* MBEDTLS_X509_CRL_PARSE_C */
+
+/*
+ * Check the signature of a certificate by its parent
+ */
+static int x509_crt_check_signature( const mbedtls_x509_crt *child,
+                                     mbedtls_x509_crt *parent,
+                                     mbedtls_x509_crt_restart_ctx *rs_ctx )
+{
+    unsigned char hash[MBEDTLS_MD_MAX_SIZE];
+    size_t hash_len;
+#if !defined(MBEDTLS_USE_PSA_CRYPTO)
+    const mbedtls_md_info_t *md_info;
+    md_info = mbedtls_md_info_from_type( child->sig_md );
+    hash_len = mbedtls_md_get_size( md_info );
+
+    /* Note: hash errors can happen only after an internal error */
+    if( mbedtls_md( md_info, child->tbs.p, child->tbs.len, hash ) != 0 )
+        return( -1 );
+#else
+    psa_hash_operation_t hash_operation = PSA_HASH_OPERATION_INIT;
+    psa_algorithm_t hash_alg = mbedtls_psa_translate_md( child->sig_md );
+
+    if( psa_hash_setup( &hash_operation, hash_alg ) != PSA_SUCCESS )
+        return( -1 );
+
+    if( psa_hash_update( &hash_operation, child->tbs.p, child->tbs.len )
+        != PSA_SUCCESS )
+    {
+        return( -1 );
+    }
+
+    if( psa_hash_finish( &hash_operation, hash, sizeof( hash ), &hash_len )
+        != PSA_SUCCESS )
+    {
+        return( -1 );
+    }
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+    /* Skip expensive computation on obvious mismatch */
+    if( ! mbedtls_pk_can_do( &parent->pk, child->sig_pk ) )
+        return( -1 );
+
+#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
+    if( rs_ctx != NULL && child->sig_pk == MBEDTLS_PK_ECDSA )
+    {
+        return( mbedtls_pk_verify_restartable( &parent->pk,
+                    child->sig_md, hash, hash_len,
+                    child->sig.p, child->sig.len, &rs_ctx->pk ) );
+    }
+#else
+    (void) rs_ctx;
+#endif
+
+    return( mbedtls_pk_verify_ext( child->sig_pk, child->sig_opts, &parent->pk,
+                child->sig_md, hash, hash_len,
+                child->sig.p, child->sig.len ) );
+}
+
+/*
+ * Check if 'parent' is a suitable parent (signing CA) for 'child'.
+ * Return 0 if yes, -1 if not.
+ *
+ * top means parent is a locally-trusted certificate
+ */
+static int x509_crt_check_parent( const mbedtls_x509_crt *child,
+                                  const mbedtls_x509_crt *parent,
+                                  int top )
+{
+    int need_ca_bit;
+
+    /* Parent must be the issuer */
+    if( x509_name_cmp( &child->issuer, &parent->subject ) != 0 )
+        return( -1 );
+
+    /* Parent must have the basicConstraints CA bit set as a general rule */
+    need_ca_bit = 1;
+
+    /* Exception: v1/v2 certificates that are locally trusted. */
+    if( top && parent->version < 3 )
+        need_ca_bit = 0;
+
+    if( need_ca_bit && ! parent->ca_istrue )
+        return( -1 );
+
+#if defined(MBEDTLS_X509_CHECK_KEY_USAGE)
+    if( need_ca_bit &&
+        mbedtls_x509_crt_check_key_usage( parent, MBEDTLS_X509_KU_KEY_CERT_SIGN ) != 0 )
+    {
+        return( -1 );
+    }
+#endif
+
+    return( 0 );
+}
+
+/*
+ * Find a suitable parent for child in candidates, or return NULL.
+ *
+ * Here suitable is defined as:
+ *  1. subject name matches child's issuer
+ *  2. if necessary, the CA bit is set and key usage allows signing certs
+ *  3. for trusted roots, the signature is correct
+ *     (for intermediates, the signature is checked and the result reported)
+ *  4. pathlen constraints are satisfied
+ *
+ * If there's a suitable candidate which is also time-valid, return the first
+ * such. Otherwise, return the first suitable candidate (or NULL if there is
+ * none).
+ *
+ * The rationale for this rule is that someone could have a list of trusted
+ * roots with two versions on the same root with different validity periods.
+ * (At least one user reported having such a list and wanted it to just work.)
+ * The reason we don't just require time-validity is that generally there is
+ * only one version, and if it's expired we want the flags to state that
+ * rather than NOT_TRUSTED, as would be the case if we required it here.
+ *
+ * The rationale for rule 3 (signature for trusted roots) is that users might
+ * have two versions of the same CA with different keys in their list, and the
+ * way we select the correct one is by checking the signature (as we don't
+ * rely on key identifier extensions). (This is one way users might choose to
+ * handle key rollover, another relies on self-issued certs, see [SIRO].)
+ *
+ * Arguments:
+ *  - [in] child: certificate for which we're looking for a parent
+ *  - [in] candidates: chained list of potential parents
+ *  - [out] r_parent: parent found (or NULL)
+ *  - [out] r_signature_is_good: 1 if child signature by parent is valid, or 0
+ *  - [in] top: 1 if candidates consists of trusted roots, ie we're at the top
+ *         of the chain, 0 otherwise
+ *  - [in] path_cnt: number of intermediates seen so far
+ *  - [in] self_cnt: number of self-signed intermediates seen so far
+ *         (will never be greater than path_cnt)
+ *  - [in-out] rs_ctx: context for restarting operations
+ *
+ * Return value:
+ *  - 0 on success
+ *  - MBEDTLS_ERR_ECP_IN_PROGRESS otherwise
+ */
+static int x509_crt_find_parent_in(
+                        mbedtls_x509_crt *child,
+                        mbedtls_x509_crt *candidates,
+                        mbedtls_x509_crt **r_parent,
+                        int *r_signature_is_good,
+                        int top,
+                        unsigned path_cnt,
+                        unsigned self_cnt,
+                        mbedtls_x509_crt_restart_ctx *rs_ctx )
+{
+    int ret;
+    mbedtls_x509_crt *parent, *fallback_parent;
+    int signature_is_good, fallback_signature_is_good;
+
+#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
+    /* did we have something in progress? */
+    if( rs_ctx != NULL && rs_ctx->parent != NULL )
+    {
+        /* restore saved state */
+        parent = rs_ctx->parent;
+        fallback_parent = rs_ctx->fallback_parent;
+        fallback_signature_is_good = rs_ctx->fallback_signature_is_good;
+
+        /* clear saved state */
+        rs_ctx->parent = NULL;
+        rs_ctx->fallback_parent = NULL;
+        rs_ctx->fallback_signature_is_good = 0;
+
+        /* resume where we left */
+        goto check_signature;
+    }
+#endif
+
+    fallback_parent = NULL;
+    fallback_signature_is_good = 0;
+
+    for( parent = candidates; parent != NULL; parent = parent->next )
+    {
+        /* basic parenting skills (name, CA bit, key usage) */
+        if( x509_crt_check_parent( child, parent, top ) != 0 )
+            continue;
+
+        /* +1 because stored max_pathlen is 1 higher that the actual value */
+        if( parent->max_pathlen > 0 &&
+            (size_t) parent->max_pathlen < 1 + path_cnt - self_cnt )
+        {
+            continue;
+        }
+
+        /* Signature */
+#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
+check_signature:
+#endif
+        ret = x509_crt_check_signature( child, parent, rs_ctx );
+
+#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
+        if( rs_ctx != NULL && ret == MBEDTLS_ERR_ECP_IN_PROGRESS )
+        {
+            /* save state */
+            rs_ctx->parent = parent;
+            rs_ctx->fallback_parent = fallback_parent;
+            rs_ctx->fallback_signature_is_good = fallback_signature_is_good;
+
+            return( ret );
+        }
+#else
+        (void) ret;
+#endif
+
+        signature_is_good = ret == 0;
+        if( top && ! signature_is_good )
+            continue;
+
+        /* optional time check */
+        if( mbedtls_x509_time_is_past( &parent->valid_to ) ||
+            mbedtls_x509_time_is_future( &parent->valid_from ) )
+        {
+            if( fallback_parent == NULL )
+            {
+                fallback_parent = parent;
+                fallback_signature_is_good = signature_is_good;
+            }
+
+            continue;
+        }
+
+        break;
+    }
+
+    if( parent != NULL )
+    {
+        *r_parent = parent;
+        *r_signature_is_good = signature_is_good;
+    }
+    else
+    {
+        *r_parent = fallback_parent;
+        *r_signature_is_good = fallback_signature_is_good;
+    }
+
+    return( 0 );
+}
+
+/*
+ * Find a parent in trusted CAs or the provided chain, or return NULL.
+ *
+ * Searches in trusted CAs first, and return the first suitable parent found
+ * (see find_parent_in() for definition of suitable).
+ *
+ * Arguments:
+ *  - [in] child: certificate for which we're looking for a parent, followed
+ *         by a chain of possible intermediates
+ *  - [in] trust_ca: list of locally trusted certificates
+ *  - [out] parent: parent found (or NULL)
+ *  - [out] parent_is_trusted: 1 if returned `parent` is trusted, or 0
+ *  - [out] signature_is_good: 1 if child signature by parent is valid, or 0
+ *  - [in] path_cnt: number of links in the chain so far (EE -> ... -> child)
+ *  - [in] self_cnt: number of self-signed certs in the chain so far
+ *         (will always be no greater than path_cnt)
+ *  - [in-out] rs_ctx: context for restarting operations
+ *
+ * Return value:
+ *  - 0 on success
+ *  - MBEDTLS_ERR_ECP_IN_PROGRESS otherwise
+ */
+static int x509_crt_find_parent(
+                        mbedtls_x509_crt *child,
+                        mbedtls_x509_crt *trust_ca,
+                        mbedtls_x509_crt **parent,
+                        int *parent_is_trusted,
+                        int *signature_is_good,
+                        unsigned path_cnt,
+                        unsigned self_cnt,
+                        mbedtls_x509_crt_restart_ctx *rs_ctx )
+{
+    int ret;
+    mbedtls_x509_crt *search_list;
+
+    *parent_is_trusted = 1;
+
+#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
+    /* restore then clear saved state if we have some stored */
+    if( rs_ctx != NULL && rs_ctx->parent_is_trusted != -1 )
+    {
+        *parent_is_trusted = rs_ctx->parent_is_trusted;
+        rs_ctx->parent_is_trusted = -1;
+    }
+#endif
+
+    while( 1 ) {
+        search_list = *parent_is_trusted ? trust_ca : child->next;
+
+        ret = x509_crt_find_parent_in( child, search_list,
+                                       parent, signature_is_good,
+                                       *parent_is_trusted,
+                                       path_cnt, self_cnt, rs_ctx );
+
+#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
+        if( rs_ctx != NULL && ret == MBEDTLS_ERR_ECP_IN_PROGRESS )
+        {
+            /* save state */
+            rs_ctx->parent_is_trusted = *parent_is_trusted;
+            return( ret );
+        }
+#else
+        (void) ret;
+#endif
+
+        /* stop here if found or already in second iteration */
+        if( *parent != NULL || *parent_is_trusted == 0 )
+            break;
+
+        /* prepare second iteration */
+        *parent_is_trusted = 0;
+    }
+
+    /* extra precaution against mistakes in the caller */
+    if( *parent == NULL )
+    {
+        *parent_is_trusted = 0;
+        *signature_is_good = 0;
+    }
+
+    return( 0 );
+}
+
+/*
+ * Check if an end-entity certificate is locally trusted
+ *
+ * Currently we require such certificates to be self-signed (actually only
+ * check for self-issued as self-signatures are not checked)
+ */
+static int x509_crt_check_ee_locally_trusted(
+                    mbedtls_x509_crt *crt,
+                    mbedtls_x509_crt *trust_ca )
+{
+    mbedtls_x509_crt *cur;
+
+    /* must be self-issued */
+    if( x509_name_cmp( &crt->issuer, &crt->subject ) != 0 )
+        return( -1 );
+
+    /* look for an exact match with trusted cert */
+    for( cur = trust_ca; cur != NULL; cur = cur->next )
+    {
+        if( crt->raw.len == cur->raw.len &&
+            memcmp( crt->raw.p, cur->raw.p, crt->raw.len ) == 0 )
+        {
+            return( 0 );
+        }
+    }
+
+    /* too bad */
+    return( -1 );
+}
+
+/*
+ * Build and verify a certificate chain
+ *
+ * Given a peer-provided list of certificates EE, C1, ..., Cn and
+ * a list of trusted certs R1, ... Rp, try to build and verify a chain
+ *      EE, Ci1, ... Ciq [, Rj]
+ * such that every cert in the chain is a child of the next one,
+ * jumping to a trusted root as early as possible.
+ *
+ * Verify that chain and return it with flags for all issues found.
+ *
+ * Special cases:
+ * - EE == Rj -> return a one-element list containing it
+ * - EE, Ci1, ..., Ciq cannot be continued with a trusted root
+ *   -> return that chain with NOT_TRUSTED set on Ciq
+ *
+ * Tests for (aspects of) this function should include at least:
+ * - trusted EE
+ * - EE -> trusted root
+ * - EE -> intermediate CA -> trusted root
+ * - if relevant: EE untrusted
+ * - if relevant: EE -> intermediate, untrusted
+ * with the aspect under test checked at each relevant level (EE, int, root).
+ * For some aspects longer chains are required, but usually length 2 is
+ * enough (but length 1 is not in general).
+ *
+ * Arguments:
+ *  - [in] crt: the cert list EE, C1, ..., Cn
+ *  - [in] trust_ca: the trusted list R1, ..., Rp
+ *  - [in] ca_crl, profile: as in verify_with_profile()
+ *  - [out] ver_chain: the built and verified chain
+ *      Only valid when return value is 0, may contain garbage otherwise!
+ *      Restart note: need not be the same when calling again to resume.
+ *  - [in-out] rs_ctx: context for restarting operations
+ *
+ * Return value:
+ *  - non-zero if the chain could not be fully built and examined
+ *  - 0 is the chain was successfully built and examined,
+ *      even if it was found to be invalid
+ */
+static int x509_crt_verify_chain(
+                mbedtls_x509_crt *crt,
+                mbedtls_x509_crt *trust_ca,
+                mbedtls_x509_crl *ca_crl,
+                mbedtls_x509_crt_ca_cb_t f_ca_cb,
+                void *p_ca_cb,
+                const mbedtls_x509_crt_profile *profile,
+                mbedtls_x509_crt_verify_chain *ver_chain,
+                mbedtls_x509_crt_restart_ctx *rs_ctx )
+{
+    /* Don't initialize any of those variables here, so that the compiler can
+     * catch potential issues with jumping ahead when restarting */
+    int ret;
+    uint32_t *flags;
+    mbedtls_x509_crt_verify_chain_item *cur;
+    mbedtls_x509_crt *child;
+    mbedtls_x509_crt *parent;
+    int parent_is_trusted;
+    int child_is_trusted;
+    int signature_is_good;
+    unsigned self_cnt;
+    mbedtls_x509_crt *cur_trust_ca = NULL;
+
+#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
+    /* resume if we had an operation in progress */
+    if( rs_ctx != NULL && rs_ctx->in_progress == x509_crt_rs_find_parent )
+    {
+        /* restore saved state */
+        *ver_chain = rs_ctx->ver_chain; /* struct copy */
+        self_cnt = rs_ctx->self_cnt;
+
+        /* restore derived state */
+        cur = &ver_chain->items[ver_chain->len - 1];
+        child = cur->crt;
+        flags = &cur->flags;
+
+        goto find_parent;
+    }
+#endif /* MBEDTLS_ECDSA_C && MBEDTLS_ECP_RESTARTABLE */
+
+    child = crt;
+    self_cnt = 0;
+    parent_is_trusted = 0;
+    child_is_trusted = 0;
+
+    while( 1 ) {
+        /* Add certificate to the verification chain */
+        cur = &ver_chain->items[ver_chain->len];
+        cur->crt = child;
+        cur->flags = 0;
+        ver_chain->len++;
+        flags = &cur->flags;
+
+        /* Check time-validity (all certificates) */
+        if( mbedtls_x509_time_is_past( &child->valid_to ) )
+            *flags |= MBEDTLS_X509_BADCERT_EXPIRED;
+
+        if( mbedtls_x509_time_is_future( &child->valid_from ) )
+            *flags |= MBEDTLS_X509_BADCERT_FUTURE;
+
+        /* Stop here for trusted roots (but not for trusted EE certs) */
+        if( child_is_trusted )
+            return( 0 );
+
+        /* Check signature algorithm: MD & PK algs */
+        if( x509_profile_check_md_alg( profile, child->sig_md ) != 0 )
+            *flags |= MBEDTLS_X509_BADCERT_BAD_MD;
+
+        if( x509_profile_check_pk_alg( profile, child->sig_pk ) != 0 )
+            *flags |= MBEDTLS_X509_BADCERT_BAD_PK;
+
+        /* Special case: EE certs that are locally trusted */
+        if( ver_chain->len == 1 &&
+            x509_crt_check_ee_locally_trusted( child, trust_ca ) == 0 )
+        {
+            return( 0 );
+        }
+
+#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
+find_parent:
+#endif
+
+        /* Obtain list of potential trusted signers from CA callback,
+         * or use statically provided list. */
+#if defined(MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK)
+        if( f_ca_cb != NULL )
+        {
+            mbedtls_x509_crt_free( ver_chain->trust_ca_cb_result );
+            mbedtls_free( ver_chain->trust_ca_cb_result );
+            ver_chain->trust_ca_cb_result = NULL;
+
+            ret = f_ca_cb( p_ca_cb, child, &ver_chain->trust_ca_cb_result );
+            if( ret != 0 )
+                return( MBEDTLS_ERR_X509_FATAL_ERROR );
+
+            cur_trust_ca = ver_chain->trust_ca_cb_result;
+        }
+        else
+#endif /* MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK */
+        {
+            ((void) f_ca_cb);
+            ((void) p_ca_cb);
+            cur_trust_ca = trust_ca;
+        }
+
+        /* Look for a parent in trusted CAs or up the chain */
+        ret = x509_crt_find_parent( child, cur_trust_ca, &parent,
+                                       &parent_is_trusted, &signature_is_good,
+                                       ver_chain->len - 1, self_cnt, rs_ctx );
+
+#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
+        if( rs_ctx != NULL && ret == MBEDTLS_ERR_ECP_IN_PROGRESS )
+        {
+            /* save state */
+            rs_ctx->in_progress = x509_crt_rs_find_parent;
+            rs_ctx->self_cnt = self_cnt;
+            rs_ctx->ver_chain = *ver_chain; /* struct copy */
+
+            return( ret );
+        }
+#else
+        (void) ret;
+#endif
+
+        /* No parent? We're done here */
+        if( parent == NULL )
+        {
+            *flags |= MBEDTLS_X509_BADCERT_NOT_TRUSTED;
+            return( 0 );
+        }
+
+        /* Count intermediate self-issued (not necessarily self-signed) certs.
+         * These can occur with some strategies for key rollover, see [SIRO],
+         * and should be excluded from max_pathlen checks. */
+        if( ver_chain->len != 1 &&
+            x509_name_cmp( &child->issuer, &child->subject ) == 0 )
+        {
+            self_cnt++;
+        }
+
+        /* path_cnt is 0 for the first intermediate CA,
+         * and if parent is trusted it's not an intermediate CA */
+        if( ! parent_is_trusted &&
+            ver_chain->len > MBEDTLS_X509_MAX_INTERMEDIATE_CA )
+        {
+            /* return immediately to avoid overflow the chain array */
+            return( MBEDTLS_ERR_X509_FATAL_ERROR );
+        }
+
+        /* signature was checked while searching parent */
+        if( ! signature_is_good )
+            *flags |= MBEDTLS_X509_BADCERT_NOT_TRUSTED;
+
+        /* check size of signing key */
+        if( x509_profile_check_key( profile, &parent->pk ) != 0 )
+            *flags |= MBEDTLS_X509_BADCERT_BAD_KEY;
+
+#if defined(MBEDTLS_X509_CRL_PARSE_C)
+        /* Check trusted CA's CRL for the given crt */
+        *flags |= x509_crt_verifycrl( child, parent, ca_crl, profile );
+#else
+        (void) ca_crl;
+#endif
+
+        /* prepare for next iteration */
+        child = parent;
+        parent = NULL;
+        child_is_trusted = parent_is_trusted;
+        signature_is_good = 0;
+    }
+}
+
+/*
+ * Check for CN match
+ */
+static int x509_crt_check_cn( const mbedtls_x509_buf *name,
+                              const char *cn, size_t cn_len )
+{
+    /* try exact match */
+    if( name->len == cn_len &&
+        x509_memcasecmp( cn, name->p, cn_len ) == 0 )
+    {
+        return( 0 );
+    }
+
+    /* try wildcard match */
+    if( x509_check_wildcard( cn, name ) == 0 )
+    {
+        return( 0 );
+    }
+
+    return( -1 );
+}
+
+/*
+ * Verify the requested CN - only call this if cn is not NULL!
+ */
+static void x509_crt_verify_name( const mbedtls_x509_crt *crt,
+                                  const char *cn,
+                                  uint32_t *flags )
+{
+    const mbedtls_x509_name *name;
+    const mbedtls_x509_sequence *cur;
+    size_t cn_len = strlen( cn );
+
+    if( crt->ext_types & MBEDTLS_X509_EXT_SUBJECT_ALT_NAME )
+    {
+        for( cur = &crt->subject_alt_names; cur != NULL; cur = cur->next )
+        {
+            if( x509_crt_check_cn( &cur->buf, cn, cn_len ) == 0 )
+                break;
+        }
+
+        if( cur == NULL )
+            *flags |= MBEDTLS_X509_BADCERT_CN_MISMATCH;
+    }
+    else
+    {
+        for( name = &crt->subject; name != NULL; name = name->next )
+        {
+            if( MBEDTLS_OID_CMP( MBEDTLS_OID_AT_CN, &name->oid ) == 0 &&
+                x509_crt_check_cn( &name->val, cn, cn_len ) == 0 )
+            {
+                break;
+            }
+        }
+
+        if( name == NULL )
+            *flags |= MBEDTLS_X509_BADCERT_CN_MISMATCH;
+    }
+}
+
+/*
+ * Merge the flags for all certs in the chain, after calling callback
+ */
+static int x509_crt_merge_flags_with_cb(
+           uint32_t *flags,
+           const mbedtls_x509_crt_verify_chain *ver_chain,
+           int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *),
+           void *p_vrfy )
+{
+    int ret;
+    unsigned i;
+    uint32_t cur_flags;
+    const mbedtls_x509_crt_verify_chain_item *cur;
+
+    for( i = ver_chain->len; i != 0; --i )
+    {
+        cur = &ver_chain->items[i-1];
+        cur_flags = cur->flags;
+
+        if( NULL != f_vrfy )
+            if( ( ret = f_vrfy( p_vrfy, cur->crt, (int) i-1, &cur_flags ) ) != 0 )
+                return( ret );
+
+        *flags |= cur_flags;
+    }
+
+    return( 0 );
+}
+
+/*
+ * Verify the certificate validity, with profile, restartable version
+ *
+ * This function:
+ *  - checks the requested CN (if any)
+ *  - checks the type and size of the EE cert's key,
+ *    as that isn't done as part of chain building/verification currently
+ *  - builds and verifies the chain
+ *  - then calls the callback and merges the flags
+ *
+ * The parameters pairs `trust_ca`, `ca_crl` and `f_ca_cb`, `p_ca_cb`
+ * are mutually exclusive: If `f_ca_cb != NULL`, it will be used by the
+ * verification routine to search for trusted signers, and CRLs will
+ * be disabled. Otherwise, `trust_ca` will be used as the static list
+ * of trusted signers, and `ca_crl` will be use as the static list
+ * of CRLs.
+ */
+static int x509_crt_verify_restartable_ca_cb( mbedtls_x509_crt *crt,
+                     mbedtls_x509_crt *trust_ca,
+                     mbedtls_x509_crl *ca_crl,
+                     mbedtls_x509_crt_ca_cb_t f_ca_cb,
+                     void *p_ca_cb,
+                     const mbedtls_x509_crt_profile *profile,
+                     const char *cn, uint32_t *flags,
+                     int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *),
+                     void *p_vrfy,
+                     mbedtls_x509_crt_restart_ctx *rs_ctx )
+{
+    int ret;
+    mbedtls_pk_type_t pk_type;
+    mbedtls_x509_crt_verify_chain ver_chain;
+    uint32_t ee_flags;
+
+    *flags = 0;
+    ee_flags = 0;
+    x509_crt_verify_chain_reset( &ver_chain );
+
+    if( profile == NULL )
+    {
+        ret = MBEDTLS_ERR_X509_BAD_INPUT_DATA;
+        goto exit;
+    }
+
+    /* check name if requested */
+    if( cn != NULL )
+        x509_crt_verify_name( crt, cn, &ee_flags );
+
+    /* Check the type and size of the key */
+    pk_type = mbedtls_pk_get_type( &crt->pk );
+
+    if( x509_profile_check_pk_alg( profile, pk_type ) != 0 )
+        ee_flags |= MBEDTLS_X509_BADCERT_BAD_PK;
+
+    if( x509_profile_check_key( profile, &crt->pk ) != 0 )
+        ee_flags |= MBEDTLS_X509_BADCERT_BAD_KEY;
+
+    /* Check the chain */
+    ret = x509_crt_verify_chain( crt, trust_ca, ca_crl,
+                                 f_ca_cb, p_ca_cb, profile,
+                                 &ver_chain, rs_ctx );
+
+    if( ret != 0 )
+        goto exit;
+
+    /* Merge end-entity flags */
+    ver_chain.items[0].flags |= ee_flags;
+
+    /* Build final flags, calling callback on the way if any */
+    ret = x509_crt_merge_flags_with_cb( flags, &ver_chain, f_vrfy, p_vrfy );
+
+exit:
+
+#if defined(MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK)
+    mbedtls_x509_crt_free( ver_chain.trust_ca_cb_result );
+    mbedtls_free( ver_chain.trust_ca_cb_result );
+    ver_chain.trust_ca_cb_result = NULL;
+#endif /* MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK */
+
+#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
+    if( rs_ctx != NULL && ret != MBEDTLS_ERR_ECP_IN_PROGRESS )
+        mbedtls_x509_crt_restart_free( rs_ctx );
+#endif
+
+    /* prevent misuse of the vrfy callback - VERIFY_FAILED would be ignored by
+     * the SSL module for authmode optional, but non-zero return from the
+     * callback means a fatal error so it shouldn't be ignored */
+    if( ret == MBEDTLS_ERR_X509_CERT_VERIFY_FAILED )
+        ret = MBEDTLS_ERR_X509_FATAL_ERROR;
+
+    if( ret != 0 )
+    {
+        *flags = (uint32_t) -1;
+        return( ret );
+    }
+
+    if( *flags != 0 )
+        return( MBEDTLS_ERR_X509_CERT_VERIFY_FAILED );
+
+    return( 0 );
+}
+
+
+/*
+ * Verify the certificate validity (default profile, not restartable)
+ */
+int mbedtls_x509_crt_verify( mbedtls_x509_crt *crt,
+                     mbedtls_x509_crt *trust_ca,
+                     mbedtls_x509_crl *ca_crl,
+                     const char *cn, uint32_t *flags,
+                     int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *),
+                     void *p_vrfy )
+{
+    return( x509_crt_verify_restartable_ca_cb( crt, trust_ca, ca_crl,
+                                         NULL, NULL,
+                                         &mbedtls_x509_crt_profile_default,
+                                         cn, flags,
+                                         f_vrfy, p_vrfy, NULL ) );
+}
+
+/*
+ * Verify the certificate validity (user-chosen profile, not restartable)
+ */
+int mbedtls_x509_crt_verify_with_profile( mbedtls_x509_crt *crt,
+                     mbedtls_x509_crt *trust_ca,
+                     mbedtls_x509_crl *ca_crl,
+                     const mbedtls_x509_crt_profile *profile,
+                     const char *cn, uint32_t *flags,
+                     int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *),
+                     void *p_vrfy )
+{
+    return( x509_crt_verify_restartable_ca_cb( crt, trust_ca, ca_crl,
+                                                 NULL, NULL,
+                                                 profile, cn, flags,
+                                                 f_vrfy, p_vrfy, NULL ) );
+}
+
+#if defined(MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK)
+/*
+ * Verify the certificate validity (user-chosen profile, CA callback,
+ *                                  not restartable).
+ */
+int mbedtls_x509_crt_verify_with_ca_cb( mbedtls_x509_crt *crt,
+                     mbedtls_x509_crt_ca_cb_t f_ca_cb,
+                     void *p_ca_cb,
+                     const mbedtls_x509_crt_profile *profile,
+                     const char *cn, uint32_t *flags,
+                     int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *),
+                     void *p_vrfy )
+{
+    return( x509_crt_verify_restartable_ca_cb( crt, NULL, NULL,
+                                                 f_ca_cb, p_ca_cb,
+                                                 profile, cn, flags,
+                                                 f_vrfy, p_vrfy, NULL ) );
+}
+#endif /* MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK */
+
+int mbedtls_x509_crt_verify_restartable( mbedtls_x509_crt *crt,
+                     mbedtls_x509_crt *trust_ca,
+                     mbedtls_x509_crl *ca_crl,
+                     const mbedtls_x509_crt_profile *profile,
+                     const char *cn, uint32_t *flags,
+                     int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *),
+                     void *p_vrfy,
+                     mbedtls_x509_crt_restart_ctx *rs_ctx )
+{
+    return( x509_crt_verify_restartable_ca_cb( crt, trust_ca, ca_crl,
+                                                 NULL, NULL,
+                                                 profile, cn, flags,
+                                                 f_vrfy, p_vrfy, rs_ctx ) );
+}
+
+
+/*
+ * Initialize a certificate chain
+ */
+void mbedtls_x509_crt_init( mbedtls_x509_crt *crt )
+{
+    memset( crt, 0, sizeof(mbedtls_x509_crt) );
+}
+
+/*
+ * Unallocate all certificate data
+ */
+void mbedtls_x509_crt_free( mbedtls_x509_crt *crt )
+{
+    mbedtls_x509_crt *cert_cur = crt;
+    mbedtls_x509_crt *cert_prv;
+    mbedtls_x509_name *name_cur;
+    mbedtls_x509_name *name_prv;
+    mbedtls_x509_sequence *seq_cur;
+    mbedtls_x509_sequence *seq_prv;
+
+    if( crt == NULL )
+        return;
+
+    do
+    {
+        mbedtls_pk_free( &cert_cur->pk );
+
+#if defined(MBEDTLS_X509_RSASSA_PSS_SUPPORT)
+        mbedtls_free( cert_cur->sig_opts );
+#endif
+
+        name_cur = cert_cur->issuer.next;
+        while( name_cur != NULL )
+        {
+            name_prv = name_cur;
+            name_cur = name_cur->next;
+            mbedtls_platform_zeroize( name_prv, sizeof( mbedtls_x509_name ) );
+            mbedtls_free( name_prv );
+        }
+
+        name_cur = cert_cur->subject.next;
+        while( name_cur != NULL )
+        {
+            name_prv = name_cur;
+            name_cur = name_cur->next;
+            mbedtls_platform_zeroize( name_prv, sizeof( mbedtls_x509_name ) );
+            mbedtls_free( name_prv );
+        }
+
+        seq_cur = cert_cur->ext_key_usage.next;
+        while( seq_cur != NULL )
+        {
+            seq_prv = seq_cur;
+            seq_cur = seq_cur->next;
+            mbedtls_platform_zeroize( seq_prv,
+                                      sizeof( mbedtls_x509_sequence ) );
+            mbedtls_free( seq_prv );
+        }
+
+        seq_cur = cert_cur->subject_alt_names.next;
+        while( seq_cur != NULL )
+        {
+            seq_prv = seq_cur;
+            seq_cur = seq_cur->next;
+            mbedtls_platform_zeroize( seq_prv,
+                                      sizeof( mbedtls_x509_sequence ) );
+            mbedtls_free( seq_prv );
+        }
+
+        if( cert_cur->raw.p != NULL && cert_cur->own_buffer )
+        {
+            mbedtls_platform_zeroize( cert_cur->raw.p, cert_cur->raw.len );
+            mbedtls_free( cert_cur->raw.p );
+        }
+
+        cert_cur = cert_cur->next;
+    }
+    while( cert_cur != NULL );
+
+    cert_cur = crt;
+    do
+    {
+        cert_prv = cert_cur;
+        cert_cur = cert_cur->next;
+
+        mbedtls_platform_zeroize( cert_prv, sizeof( mbedtls_x509_crt ) );
+        if( cert_prv != crt )
+            mbedtls_free( cert_prv );
+    }
+    while( cert_cur != NULL );
+}
+
+#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
+/*
+ * Initialize a restart context
+ */
+void mbedtls_x509_crt_restart_init( mbedtls_x509_crt_restart_ctx *ctx )
+{
+    mbedtls_pk_restart_init( &ctx->pk );
+
+    ctx->parent = NULL;
+    ctx->fallback_parent = NULL;
+    ctx->fallback_signature_is_good = 0;
+
+    ctx->parent_is_trusted = -1;
+
+    ctx->in_progress = x509_crt_rs_none;
+    ctx->self_cnt = 0;
+    x509_crt_verify_chain_reset( &ctx->ver_chain );
+}
+
+/*
+ * Free the components of a restart context
+ */
+void mbedtls_x509_crt_restart_free( mbedtls_x509_crt_restart_ctx *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    mbedtls_pk_restart_free( &ctx->pk );
+    mbedtls_x509_crt_restart_init( ctx );
+}
+#endif /* MBEDTLS_ECDSA_C && MBEDTLS_ECP_RESTARTABLE */
+
+#endif /* MBEDTLS_X509_CRT_PARSE_C */