Merge remote-tracking branch 'upstream-public/pr/1958' into development
diff --git a/ChangeLog b/ChangeLog
index 3f23854..266b035 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -30,6 +30,7 @@
      primitive. Fixes #1798.
      mbedtls_ctr_drbg_update() -> mbedtls_ctr_drbg_update_ret()
      mbedtls_hmac_drbg_update() -> mbedtls_hmac_drbg_update_ret()
+   * Extend ECDH interface to enable alternative implementations.
 
 New deprecations
    * Deprecate mbedtls_ctr_drbg_update and mbedtls_hmac_drbg_update
diff --git a/include/mbedtls/debug.h b/include/mbedtls/debug.h
index ef8db67..736444b 100644
--- a/include/mbedtls/debug.h
+++ b/include/mbedtls/debug.h
@@ -65,6 +65,11 @@
     mbedtls_debug_print_crt( ssl, level, __FILE__, __LINE__, text, crt )
 #endif
 
+#if defined(MBEDTLS_ECDH_C)
+#define MBEDTLS_SSL_DEBUG_ECDH( level, ecdh, attr )               \
+    mbedtls_debug_printf_ecdh( ssl, level, __FILE__, __LINE__, ecdh, attr )
+#endif
+
 #else /* MBEDTLS_DEBUG_C */
 
 #define MBEDTLS_SSL_DEBUG_MSG( level, args )            do { } while( 0 )
@@ -73,6 +78,7 @@
 #define MBEDTLS_SSL_DEBUG_MPI( level, text, X )         do { } while( 0 )
 #define MBEDTLS_SSL_DEBUG_ECP( level, text, X )         do { } while( 0 )
 #define MBEDTLS_SSL_DEBUG_CRT( level, text, crt )       do { } while( 0 )
+#define MBEDTLS_SSL_DEBUG_ECDH( level, ecdh, attr )     do { } while( 0 )
 
 #endif /* MBEDTLS_DEBUG_C */
 
@@ -221,6 +227,36 @@
                       const char *text, const mbedtls_x509_crt *crt );
 #endif
 
+#if defined(MBEDTLS_ECDH_C)
+typedef enum
+{
+    MBEDTLS_DEBUG_ECDH_Q,
+    MBEDTLS_DEBUG_ECDH_QP,
+    MBEDTLS_DEBUG_ECDH_Z,
+} mbedtls_debug_ecdh_attr;
+
+/**
+ * \brief   Print a field of the ECDH structure in the SSL context to the debug
+ *          output. This function is always used through the
+ *          MBEDTLS_SSL_DEBUG_ECDH() macro, which supplies the ssl context, file
+ *          and line number parameters.
+ *
+ * \param ssl       SSL context
+ * \param level     error level of the debug message
+ * \param file      file the error has occurred in
+ * \param line      line number the error has occurred in
+ * \param ecdh      the ECDH context
+ * \param attr      the identifier of the attribute being output
+ *
+ * \attention       This function is intended for INTERNAL usage within the
+ *                  library only.
+ */
+void mbedtls_debug_printf_ecdh( const mbedtls_ssl_context *ssl, int level,
+                                const char *file, int line,
+                                const mbedtls_ecdh_context *ecdh,
+                                mbedtls_debug_ecdh_attr attr );
+#endif
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/include/mbedtls/ecdh.h b/include/mbedtls/ecdh.h
index 27f2ffc..cbd4841 100644
--- a/include/mbedtls/ecdh.h
+++ b/include/mbedtls/ecdh.h
@@ -36,6 +36,18 @@
 
 #include "ecp.h"
 
+/*
+ * Use a backward compatible ECDH context.
+ *
+ * This flag is always enabled for now and future versions might add a
+ * configuration option that conditionally undefines this flag.
+ * The configuration option in question may have a different name.
+ *
+ * Features undefining this flag, must have a warning in their description in
+ * config.h stating that the feature breaks backward compatibility.
+ */
+#define MBEDTLS_ECDH_LEGACY_CONTEXT
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -49,6 +61,39 @@
     MBEDTLS_ECDH_THEIRS, /**< The key of the peer. */
 } mbedtls_ecdh_side;
 
+#if !defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+/**
+ * Defines the ECDH implementation used.
+ *
+ * Later versions of the library may add new variants, therefore users should
+ * not make any assumptions about them.
+ */
+typedef enum
+{
+    MBEDTLS_ECDH_VARIANT_NONE = 0,   /*!< Implementation not defined. */
+    MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0,/*!< The default Mbed TLS implementation */
+} mbedtls_ecdh_variant;
+
+/**
+ * The context used by the default ECDH implementation.
+ *
+ * Later versions might change the structure of this context, therefore users
+ * should not make any assumptions about the structure of
+ * mbedtls_ecdh_context_mbed.
+ */
+typedef struct mbedtls_ecdh_context_mbed
+{
+    mbedtls_ecp_group grp;   /*!< The elliptic curve used. */
+    mbedtls_mpi d;           /*!< The private key. */
+    mbedtls_ecp_point Q;     /*!< The public key. */
+    mbedtls_ecp_point Qp;    /*!< The value of the public key of the peer. */
+    mbedtls_mpi z;           /*!< The shared secret. */
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+    mbedtls_ecp_restart_ctx rs; /*!< The restart context for EC computations. */
+#endif
+} mbedtls_ecdh_context_mbed;
+#endif
+
 /**
  *
  * \warning         Performing multiple operations concurrently on the same
@@ -58,6 +103,7 @@
  */
 typedef struct mbedtls_ecdh_context
 {
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
     mbedtls_ecp_group grp;   /*!< The elliptic curve used. */
     mbedtls_mpi d;           /*!< The private key. */
     mbedtls_ecp_point Q;     /*!< The public key. */
@@ -70,7 +116,26 @@
 #if defined(MBEDTLS_ECP_RESTARTABLE)
     int restart_enabled;        /*!< The flag for restartable mode. */
     mbedtls_ecp_restart_ctx rs; /*!< The restart context for EC computations. */
-#endif
+#endif /* MBEDTLS_ECP_RESTARTABLE */
+#else
+    uint8_t point_format;       /*!< The format of point export in TLS messages
+                                  as defined in RFC 4492. */
+    mbedtls_ecp_group_id grp_id;/*!< The elliptic curve used. */
+    mbedtls_ecdh_variant var;   /*!< The ECDH implementation/structure used. */
+    union
+    {
+        mbedtls_ecdh_context_mbed   mbed_ecdh;
+    } ctx;                      /*!< Implementation-specific context. The
+                                  context in use is specified by the \c var
+                                  field. */
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+    uint8_t restart_enabled;    /*!< The flag for restartable mode. Functions of
+                                  an alternative implementation not supporting
+                                  restartable mode must return
+                                  MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED error
+                                  if this flag is set. */
+#endif /* MBEDTLS_ECP_RESTARTABLE */
+#endif /* MBEDTLS_ECDH_LEGACY_CONTEXT */
 }
 mbedtls_ecdh_context;
 
@@ -135,6 +200,24 @@
 void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx );
 
 /**
+ * \brief           This function sets up the ECDH context with the information
+ *                  given.
+ *
+ *                  This function should be called after mbedtls_ecdh_init() but
+ *                  before mbedtls_ecdh_make_params(). There is no need to call
+ *                  this function before mbedtls_ecdh_read_params().
+ *
+ *                  This is the first function used by a TLS server for ECDHE
+ *                  ciphersuites.
+ *
+ * \param ctx       The ECDH context to set up.
+ * \param grp_id    The group id of the group to set up the context for.
+ *
+ * \return          \c 0 on success.
+ */
+int mbedtls_ecdh_setup( mbedtls_ecdh_context *ctx, mbedtls_ecp_group_id grp_id );
+
+/**
  * \brief           This function frees a context.
  *
  * \param ctx       The context to free.
@@ -145,8 +228,8 @@
  * \brief           This function generates a public key and a TLS
  *                  ServerKeyExchange payload.
  *
- *                  This is the first function used by a TLS server for ECDHE
- *                  ciphersuites.
+ *                  This is the second function used by a TLS server for ECDHE
+ *                  ciphersuites. (It is called after mbedtls_ecdh_setup().)
  *
  * \note            This function assumes that the ECP group (grp) of the
  *                  \p ctx context has already been properly set,
@@ -242,8 +325,9 @@
  * \brief       This function parses and processes a TLS ClientKeyExchange
  *              payload.
  *
- *              This is the second function used by a TLS server for ECDH(E)
- *              ciphersuites.
+ *              This is the third function used by a TLS server for ECDH(E)
+ *              ciphersuites. (It is called after mbedtls_ecdh_setup() and
+ *              mbedtls_ecdh_make_params().)
  *
  * \see         ecp.h
  *
diff --git a/include/mbedtls/ecp.h b/include/mbedtls/ecp.h
index 2fb1af4..1c37298 100644
--- a/include/mbedtls/ecp.h
+++ b/include/mbedtls/ecp.h
@@ -159,6 +159,10 @@
  * additions or subtractions. Therefore, it is only an approximative modular
  * reduction. It must return 0 on success and non-zero on failure.
  *
+ * \note        Alternative implementations must keep the group IDs distinct. If
+ *              two group structures have the same ID, then they must be
+ *              identical.
+ *
  */
 typedef struct mbedtls_ecp_group
 {
@@ -632,7 +636,7 @@
 /**
  * \brief           This function imports a point from a TLS ECPoint record.
  *
- * \note            On function return, \p buf is updated to point to immediately
+ * \note            On function return, \p *buf is updated to point immediately
  *                  after the ECPoint record.
  *
  * \param grp       The ECP group used.
@@ -641,7 +645,8 @@
  * \param len       The length of the buffer.
  *
  * \return          \c 0 on success.
- * \return          An \c MBEDTLS_ERR_MPI_XXX error code on initialization failure.
+ * \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,
@@ -687,20 +692,40 @@
 /**
  * \brief           This function sets a group from a TLS ECParameters record.
  *
- * \note            \p buf is updated to point right after the ECParameters record
- *                  on exit.
+ * \note            \p buf is updated to point right after the ECParameters
+ *                  record 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          \c 0 on success.
- * \return          An \c MBEDTLS_ERR_MPI_XXX error code on initialization failure.
+ * \return          An \c MBEDTLS_ERR_MPI_XXX error code on initialization
+ *                  failure.
  * \return          #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if input is invalid.
+ * \return          #MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE if the group is not
+ *                  recognised.
  */
 int mbedtls_ecp_tls_read_group( mbedtls_ecp_group *grp, const unsigned char **buf, size_t len );
 
 /**
+ * \brief           This function reads a group from a TLS ECParameters record.
+ *
+ * \note            \p buf is updated to point right after the ECParameters
+ *                  record on exit.
+ *
+ * \param grp       Output parameter to hold the group id.
+ * \param buf       The address of the pointer to the start of the input buffer.
+ * \param len       The length of the buffer.
+ *
+ * \return          \c 0 on success.
+ * \return          #MBEDTLS_ERR_ECP_BAD_INPUT_DATA if input is invalid.
+ * \return          #MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE if the group is not
+ *                  recognised.
+ */
+int mbedtls_ecp_tls_read_group_id( mbedtls_ecp_group_id *grp,
+                                   const unsigned char **buf, size_t len );
+/**
  * \brief           This function writes the TLS ECParameters record for a group.
  *
  * \param grp       The ECP group used.
diff --git a/library/debug.c b/library/debug.c
index db3924a..824cd02 100644
--- a/library/debug.c
+++ b/library/debug.c
@@ -365,4 +365,54 @@
 }
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
 
+#if defined(MBEDTLS_ECDH_C)
+static void mbedtls_debug_printf_ecdh_internal( const mbedtls_ssl_context *ssl,
+                                                int level, const char *file,
+                                                int line,
+                                                const mbedtls_ecdh_context *ecdh,
+                                                mbedtls_debug_ecdh_attr attr )
+{
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+    const mbedtls_ecdh_context* ctx = ecdh;
+#else
+    const mbedtls_ecdh_context_mbed* ctx = &ecdh->ctx.mbed_ecdh;
+#endif
+
+    switch( attr )
+    {
+        case MBEDTLS_DEBUG_ECDH_Q:
+            mbedtls_debug_print_ecp( ssl, level, file, line, "ECDH: Q",
+                                     &ctx->Q );
+            break;
+        case MBEDTLS_DEBUG_ECDH_QP:
+            mbedtls_debug_print_ecp( ssl, level, file, line, "ECDH: Qp",
+                                     &ctx->Qp );
+            break;
+        case MBEDTLS_DEBUG_ECDH_Z:
+            mbedtls_debug_print_mpi( ssl, level, file, line, "ECDH: z",
+                                     &ctx->z );
+            break;
+        default:
+            break;
+    }
+}
+
+void mbedtls_debug_printf_ecdh( const mbedtls_ssl_context *ssl, int level,
+                                const char *file, int line,
+                                const mbedtls_ecdh_context *ecdh,
+                                mbedtls_debug_ecdh_attr attr )
+{
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+    mbedtls_debug_printf_ecdh_internal( ssl, level, file, line, ecdh, attr );
+#else
+    switch( ecdh->var )
+    {
+        default:
+            mbedtls_debug_printf_ecdh_internal( ssl, level, file, line, ecdh,
+                                                attr );
+    }
+#endif
+}
+#endif /* MBEDTLS_ECDH_C */
+
 #endif /* MBEDTLS_DEBUG_C */
diff --git a/library/ecdh.c b/library/ecdh.c
index e6ae999..d68db8a 100644
--- a/library/ecdh.c
+++ b/library/ecdh.c
@@ -38,6 +38,10 @@
 
 #include <string.h>
 
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+typedef mbedtls_ecdh_context mbedtls_ecdh_context_mbed;
+#endif
+
 #if !defined(MBEDTLS_ECDH_GEN_PUBLIC_ALT)
 /*
  * Generate public key (restartable version)
@@ -124,43 +128,84 @@
 }
 #endif /* !MBEDTLS_ECDH_COMPUTE_SHARED_ALT */
 
-/*
- * Initialize context
- */
-void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx )
+static void ecdh_init_internal( mbedtls_ecdh_context_mbed *ctx )
 {
     mbedtls_ecp_group_init( &ctx->grp );
     mbedtls_mpi_init( &ctx->d  );
     mbedtls_ecp_point_init( &ctx->Q   );
     mbedtls_ecp_point_init( &ctx->Qp  );
     mbedtls_mpi_init( &ctx->z  );
-    ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
-    mbedtls_ecp_point_init( &ctx->Vi  );
-    mbedtls_ecp_point_init( &ctx->Vf  );
-    mbedtls_mpi_init( &ctx->_d );
 
 #if defined(MBEDTLS_ECP_RESTARTABLE)
-    ctx->restart_enabled = 0;
     mbedtls_ecp_restart_init( &ctx->rs );
 #endif
 }
 
 /*
- * Free context
+ * Initialize context
  */
-void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx )
+void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx )
+{
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+    ecdh_init_internal( ctx );
+    mbedtls_ecp_point_init( &ctx->Vi  );
+    mbedtls_ecp_point_init( &ctx->Vf  );
+    mbedtls_mpi_init( &ctx->_d );
+#else
+    memset( ctx, 0, sizeof( mbedtls_ecdh_context ) );
+
+    ctx->var = MBEDTLS_ECDH_VARIANT_NONE;
+#endif
+    ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+    ctx->restart_enabled = 0;
+#endif
+}
+
+static int ecdh_setup_internal( mbedtls_ecdh_context_mbed *ctx,
+                                mbedtls_ecp_group_id grp_id )
+{
+    int ret;
+
+    ret = mbedtls_ecp_group_load( &ctx->grp, grp_id );
+    if( ret != 0 )
+    {
+        return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
+    }
+
+    return( 0 );
+}
+
+/*
+ * Setup context
+ */
+int mbedtls_ecdh_setup( mbedtls_ecdh_context *ctx, mbedtls_ecp_group_id grp_id )
 {
     if( ctx == NULL )
-        return;
+        return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
 
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+    return( ecdh_setup_internal( ctx, grp_id ) );
+#else
+    switch( grp_id )
+    {
+        default:
+            ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
+            ctx->var = MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0;
+            ctx->grp_id = grp_id;
+            ecdh_init_internal( &ctx->ctx.mbed_ecdh );
+            return( ecdh_setup_internal( &ctx->ctx.mbed_ecdh, grp_id ) );
+    }
+#endif
+}
+
+static void ecdh_free_internal( mbedtls_ecdh_context_mbed *ctx )
+{
     mbedtls_ecp_group_free( &ctx->grp );
     mbedtls_mpi_free( &ctx->d  );
     mbedtls_ecp_point_free( &ctx->Q   );
     mbedtls_ecp_point_free( &ctx->Qp  );
     mbedtls_mpi_free( &ctx->z  );
-    mbedtls_ecp_point_free( &ctx->Vi  );
-    mbedtls_ecp_point_free( &ctx->Vf  );
-    mbedtls_mpi_free( &ctx->_d );
 
 #if defined(MBEDTLS_ECP_RESTARTABLE)
     mbedtls_ecp_restart_free( &ctx->rs );
@@ -173,21 +218,50 @@
  */
 void mbedtls_ecdh_enable_restart( mbedtls_ecdh_context *ctx )
 {
+    if( ctx == NULL )
+        return;
+
     ctx->restart_enabled = 1;
 }
 #endif
 
 /*
- * Setup and write the ServerKeyExhange parameters (RFC 4492)
- *      struct {
- *          ECParameters    curve_params;
- *          ECPoint         public;
- *      } ServerECDHParams;
+ * Free context
  */
-int mbedtls_ecdh_make_params( mbedtls_ecdh_context *ctx, size_t *olen,
-                      unsigned char *buf, size_t blen,
-                      int (*f_rng)(void *, unsigned char *, size_t),
-                      void *p_rng )
+void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+    mbedtls_ecp_point_free( &ctx->Vi );
+    mbedtls_ecp_point_free( &ctx->Vf );
+    mbedtls_mpi_free( &ctx->_d );
+    ecdh_free_internal( ctx );
+#else
+    switch( ctx->var )
+    {
+        case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
+            ecdh_free_internal( &ctx->ctx.mbed_ecdh );
+            break;
+        default:
+            break;
+    }
+
+    ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
+    ctx->var = MBEDTLS_ECDH_VARIANT_NONE;
+    ctx->grp_id = MBEDTLS_ECP_DP_NONE;
+#endif
+}
+
+static int ecdh_make_params_internal( mbedtls_ecdh_context_mbed *ctx,
+                                      size_t *olen, int point_format,
+                                      unsigned char *buf, size_t blen,
+                                      int (*f_rng)(void *,
+                                                   unsigned char *,
+                                                   size_t),
+                                      void *p_rng,
+                                      int restart_enabled )
 {
     int ret;
     size_t grp_len, pt_len;
@@ -195,12 +269,14 @@
     mbedtls_ecp_restart_ctx *rs_ctx = NULL;
 #endif
 
-    if( ctx == NULL || ctx->grp.pbits == 0 )
+    if( ctx->grp.pbits == 0 )
         return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
 
 #if defined(MBEDTLS_ECP_RESTARTABLE)
-    if( ctx->restart_enabled )
+    if( restart_enabled )
         rs_ctx = &ctx->rs;
+#else
+    (void) restart_enabled;
 #endif
 
 
@@ -214,14 +290,14 @@
         return( ret );
 #endif /* MBEDTLS_ECP_RESTARTABLE */
 
-    if( ( ret = mbedtls_ecp_tls_write_group( &ctx->grp, &grp_len, buf, blen ) )
-                != 0 )
+    if( ( ret = mbedtls_ecp_tls_write_group( &ctx->grp, &grp_len, buf,
+                                             blen ) ) != 0 )
         return( ret );
 
     buf += grp_len;
     blen -= grp_len;
 
-    if( ( ret = mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format,
+    if( ( ret = mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, point_format,
                                              &pt_len, buf, blen ) ) != 0 )
         return( ret );
 
@@ -230,6 +306,54 @@
 }
 
 /*
+ * Setup and write the ServerKeyExhange parameters (RFC 4492)
+ *      struct {
+ *          ECParameters    curve_params;
+ *          ECPoint         public;
+ *      } ServerECDHParams;
+ */
+int mbedtls_ecdh_make_params( mbedtls_ecdh_context *ctx, size_t *olen,
+                              unsigned char *buf, size_t blen,
+                              int (*f_rng)(void *, unsigned char *, size_t),
+                              void *p_rng )
+{
+    int restart_enabled = 0;
+
+    if( ctx == NULL )
+        return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+    restart_enabled = ctx->restart_enabled;
+#else
+    (void) restart_enabled;
+#endif
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+    return( ecdh_make_params_internal( ctx, olen, ctx->point_format, buf, blen,
+                                       f_rng, p_rng, restart_enabled ) );
+#else
+    switch( ctx->var )
+    {
+        case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
+            return( ecdh_make_params_internal( &ctx->ctx.mbed_ecdh, olen,
+                                               ctx->point_format, buf, blen,
+                                               f_rng, p_rng,
+                                               restart_enabled ) );
+        default:
+            return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
+    }
+#endif
+}
+
+static int ecdh_read_params_internal( mbedtls_ecdh_context_mbed *ctx,
+                                      const unsigned char **buf,
+                                      const unsigned char *end )
+{
+    return( mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, buf,
+                                        end - *buf ) );
+}
+
+/*
  * Read the ServerKeyExhange parameters (RFC 4492)
  *      struct {
  *          ECParameters    curve_params;
@@ -237,31 +361,42 @@
  *      } ServerECDHParams;
  */
 int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx,
-                      const unsigned char **buf, const unsigned char *end )
+                              const unsigned char **buf,
+                              const unsigned char *end )
 {
     int ret;
+    mbedtls_ecp_group_id grp_id;
 
-    if( ( ret = mbedtls_ecp_tls_read_group( &ctx->grp, buf, end - *buf ) ) != 0 )
+    if( ctx == NULL )
+        return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+    if( ( ret = mbedtls_ecp_tls_read_group_id( &grp_id, buf, end - *buf ) )
+            != 0 )
         return( ret );
 
-    if( ( ret = mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, buf, end - *buf ) )
-                != 0 )
+    if( ( ret = mbedtls_ecdh_setup( ctx, grp_id ) ) != 0 )
         return( ret );
 
-    return( 0 );
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+    return( ecdh_read_params_internal( ctx, buf, end ) );
+#else
+    switch( ctx->var )
+    {
+        case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
+            return( ecdh_read_params_internal( &ctx->ctx.mbed_ecdh,
+                                               buf, end ) );
+        default:
+            return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
+    }
+#endif
 }
 
-/*
- * Get parameters from a keypair
- */
-int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx, const mbedtls_ecp_keypair *key,
-                     mbedtls_ecdh_side side )
+static int ecdh_get_params_internal( mbedtls_ecdh_context_mbed *ctx,
+                                     const mbedtls_ecp_keypair *key,
+                                     mbedtls_ecdh_side side )
 {
     int ret;
 
-    if( ( ret = mbedtls_ecp_group_copy( &ctx->grp, &key->grp ) ) != 0 )
-        return( ret );
-
     /* If it's not our key, just import the public part as Qp */
     if( side == MBEDTLS_ECDH_THEIRS )
         return( mbedtls_ecp_copy( &ctx->Qp, &key->Q ) );
@@ -278,29 +413,61 @@
 }
 
 /*
- * Setup and export the client public value
+ * Get parameters from a keypair
  */
-int mbedtls_ecdh_make_public( mbedtls_ecdh_context *ctx, size_t *olen,
-                      unsigned char *buf, size_t blen,
-                      int (*f_rng)(void *, unsigned char *, size_t),
-                      void *p_rng )
+int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx,
+                             const mbedtls_ecp_keypair *key,
+                             mbedtls_ecdh_side side )
+{
+    int ret;
+
+    if( ctx == NULL )
+        return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+    if( ( ret = mbedtls_ecdh_setup( ctx, key->grp.id ) ) != 0 )
+        return( ret );
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+    return( ecdh_get_params_internal( ctx, key, side ) );
+#else
+    switch( ctx->var )
+    {
+        case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
+            return( ecdh_get_params_internal( &ctx->ctx.mbed_ecdh,
+                                              key, side ) );
+        default:
+            return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
+    }
+#endif
+}
+
+static int ecdh_make_public_internal( mbedtls_ecdh_context_mbed *ctx,
+                                      size_t *olen, int point_format,
+                                      unsigned char *buf, size_t blen,
+                                      int (*f_rng)(void *,
+                                                   unsigned char *,
+                                                   size_t),
+                                      void *p_rng,
+                                      int restart_enabled )
 {
     int ret;
 #if defined(MBEDTLS_ECP_RESTARTABLE)
     mbedtls_ecp_restart_ctx *rs_ctx = NULL;
 #endif
 
-    if( ctx == NULL || ctx->grp.pbits == 0 )
+    if( ctx->grp.pbits == 0 )
         return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
 
 #if defined(MBEDTLS_ECP_RESTARTABLE)
-    if( ctx->restart_enabled )
+    if( restart_enabled )
         rs_ctx = &ctx->rs;
+#else
+    (void) restart_enabled;
 #endif
 
 #if defined(MBEDTLS_ECP_RESTARTABLE)
     if( ( ret = ecdh_gen_public_restartable( &ctx->grp, &ctx->d, &ctx->Q,
-                    f_rng, p_rng, rs_ctx ) ) != 0 )
+                                             f_rng, p_rng, rs_ctx ) ) != 0 )
         return( ret );
 #else
     if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q,
@@ -308,23 +475,52 @@
         return( ret );
 #endif /* MBEDTLS_ECP_RESTARTABLE */
 
-    return mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format,
-                                olen, buf, blen );
+    return mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, point_format, olen,
+                                        buf, blen );
 }
 
 /*
- * Parse and import the client's public value
+ * Setup and export the client public value
  */
-int mbedtls_ecdh_read_public( mbedtls_ecdh_context *ctx,
-                      const unsigned char *buf, size_t blen )
+int mbedtls_ecdh_make_public( mbedtls_ecdh_context *ctx, size_t *olen,
+                              unsigned char *buf, size_t blen,
+                              int (*f_rng)(void *, unsigned char *, size_t),
+                              void *p_rng )
 {
-    int ret;
-    const unsigned char *p = buf;
+    int restart_enabled = 0;
 
     if( ctx == NULL )
         return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
 
-    if( ( ret = mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, &p, blen ) ) != 0 )
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+    restart_enabled = ctx->restart_enabled;
+#endif
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+    return( ecdh_make_public_internal( ctx, olen, ctx->point_format, buf, blen,
+                                       f_rng, p_rng, restart_enabled ) );
+#else
+    switch( ctx->var )
+    {
+        case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
+            return( ecdh_make_public_internal( &ctx->ctx.mbed_ecdh, olen,
+                                               ctx->point_format, buf, blen,
+                                               f_rng, p_rng,
+                                               restart_enabled ) );
+        default:
+            return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
+    }
+#endif
+}
+
+static int ecdh_read_public_internal( mbedtls_ecdh_context_mbed *ctx,
+                                      const unsigned char *buf, size_t blen )
+{
+    int ret;
+    const unsigned char *p = buf;
+
+    if( ( ret = mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, &p,
+                                            blen ) ) != 0 )
         return( ret );
 
     if( (size_t)( p - buf ) != blen )
@@ -334,12 +530,36 @@
 }
 
 /*
- * Derive and export the shared secret
+ * Parse and import the client's public value
  */
-int mbedtls_ecdh_calc_secret( mbedtls_ecdh_context *ctx, size_t *olen,
-                      unsigned char *buf, size_t blen,
-                      int (*f_rng)(void *, unsigned char *, size_t),
-                      void *p_rng )
+int mbedtls_ecdh_read_public( mbedtls_ecdh_context *ctx,
+                              const unsigned char *buf, size_t blen )
+{
+    if( ctx == NULL )
+        return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+    return( ecdh_read_public_internal( ctx, buf, blen ) );
+#else
+    switch( ctx->var )
+    {
+        case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
+            return( ecdh_read_public_internal( &ctx->ctx.mbed_ecdh,
+                                                       buf, blen ) );
+        default:
+            return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
+    }
+#endif
+}
+
+static int ecdh_calc_secret_internal( mbedtls_ecdh_context_mbed *ctx,
+                                      size_t *olen, unsigned char *buf,
+                                      size_t blen,
+                                      int (*f_rng)(void *,
+                                                   unsigned char *,
+                                                   size_t),
+                                      void *p_rng,
+                                      int restart_enabled )
 {
     int ret;
 #if defined(MBEDTLS_ECP_RESTARTABLE)
@@ -350,13 +570,16 @@
         return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
 
 #if defined(MBEDTLS_ECP_RESTARTABLE)
-    if( ctx->restart_enabled )
+    if( restart_enabled )
         rs_ctx = &ctx->rs;
+#else
+    (void) restart_enabled;
 #endif
 
 #if defined(MBEDTLS_ECP_RESTARTABLE)
-    if( ( ret = ecdh_compute_shared_restartable( &ctx->grp,
-                    &ctx->z, &ctx->Qp, &ctx->d, f_rng, p_rng, rs_ctx ) ) != 0 )
+    if( ( ret = ecdh_compute_shared_restartable( &ctx->grp, &ctx->z, &ctx->Qp,
+                                                 &ctx->d, f_rng, p_rng,
+                                                 rs_ctx ) ) != 0 )
     {
         return( ret );
     }
@@ -375,4 +598,37 @@
     return mbedtls_mpi_write_binary( &ctx->z, buf, *olen );
 }
 
+/*
+ * Derive and export the shared secret
+ */
+int mbedtls_ecdh_calc_secret( mbedtls_ecdh_context *ctx, size_t *olen,
+                              unsigned char *buf, size_t blen,
+                              int (*f_rng)(void *, unsigned char *, size_t),
+                              void *p_rng )
+{
+    int restart_enabled = 0;
+
+    if( ctx == NULL )
+        return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+    restart_enabled = ctx->restart_enabled;
+#endif
+
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+    return( ecdh_calc_secret_internal( ctx, olen, buf, blen, f_rng, p_rng,
+                                       restart_enabled ) );
+#else
+    switch( ctx->var )
+    {
+        case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
+            return( ecdh_calc_secret_internal( &ctx->ctx.mbed_ecdh, olen, buf,
+                                               blen, f_rng, p_rng,
+                                               restart_enabled ) );
+        default:
+            return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
+    }
+#endif
+}
+
 #endif /* MBEDTLS_ECDH_C */
diff --git a/library/ecp.c b/library/ecp.c
index de5725c..49255b1 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -833,7 +833,24 @@
 /*
  * Set a group from an ECParameters record (RFC 4492)
  */
-int mbedtls_ecp_tls_read_group( mbedtls_ecp_group *grp, const unsigned char **buf, size_t len )
+int mbedtls_ecp_tls_read_group( mbedtls_ecp_group *grp,
+                                const unsigned char **buf, size_t len )
+{
+    int ret;
+    mbedtls_ecp_group_id grp_id;
+
+    if( ( ret = mbedtls_ecp_tls_read_group_id( &grp_id, buf, len ) ) != 0 )
+        return( ret );
+
+    return mbedtls_ecp_group_load( grp, grp_id );
+}
+
+/*
+ * Read a group id from an ECParameters record (RFC 4492) and convert it to
+ * mbedtls_ecp_group_id.
+ */
+int mbedtls_ecp_tls_read_group_id( mbedtls_ecp_group_id *grp,
+                                   const unsigned char **buf, size_t len )
 {
     uint16_t tls_id;
     const mbedtls_ecp_curve_info *curve_info;
@@ -860,7 +877,9 @@
     if( ( curve_info = mbedtls_ecp_curve_info_from_tls_id( tls_id ) ) == NULL )
         return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
 
-    return mbedtls_ecp_group_load( grp, curve_info->grp_id );
+    *grp = curve_info->grp_id;
+
+    return( 0 );
 }
 
 /*
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index ff576f3..afced7a 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -2027,8 +2027,14 @@
 static int ssl_check_server_ecdh_params( const mbedtls_ssl_context *ssl )
 {
     const mbedtls_ecp_curve_info *curve_info;
+    mbedtls_ecp_group_id grp_id;
+#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
+    grp_id = ssl->handshake->ecdh_ctx.grp.id;
+#else
+    grp_id = ssl->handshake->ecdh_ctx.grp_id;
+#endif
 
-    curve_info = mbedtls_ecp_curve_info_from_grp_id( ssl->handshake->ecdh_ctx.grp.id );
+    curve_info = mbedtls_ecp_curve_info_from_grp_id( grp_id );
     if( curve_info == NULL )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
@@ -2038,14 +2044,15 @@
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "ECDH curve: %s", curve_info->name ) );
 
 #if defined(MBEDTLS_ECP_C)
-    if( mbedtls_ssl_check_curve( ssl, ssl->handshake->ecdh_ctx.grp.id ) != 0 )
+    if( mbedtls_ssl_check_curve( ssl, grp_id ) != 0 )
 #else
     if( ssl->handshake->ecdh_ctx.grp.nbits < 163 ||
         ssl->handshake->ecdh_ctx.grp.nbits > 521 )
 #endif
         return( -1 );
 
-    MBEDTLS_SSL_DEBUG_ECP( 3, "ECDH: Qp", &ssl->handshake->ecdh_ctx.Qp );
+    MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
+                            MBEDTLS_DEBUG_ECDH_QP );
 
     return( 0 );
 }
@@ -2967,7 +2974,8 @@
             return( ret );
         }
 
-        MBEDTLS_SSL_DEBUG_ECP( 3, "ECDH: Q", &ssl->handshake->ecdh_ctx.Q );
+        MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
+                                MBEDTLS_DEBUG_ECDH_Q );
 
 #if defined(MBEDTLS_SSL__ECP_RESTARTABLE)
         if( ssl->handshake->ecrs_enabled )
@@ -2994,7 +3002,8 @@
             return( ret );
         }
 
-        MBEDTLS_SSL_DEBUG_MPI( 3, "ECDH: z", &ssl->handshake->ecdh_ctx.z );
+        MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
+                                MBEDTLS_DEBUG_ECDH_Z );
     }
     else
 #endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED ||
@@ -3089,7 +3098,8 @@
                 return( ret );
             }
 
-            MBEDTLS_SSL_DEBUG_ECP( 3, "ECDH: Q", &ssl->handshake->ecdh_ctx.Q );
+            MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
+                                    MBEDTLS_DEBUG_ECDH_Q );
         }
         else
 #endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED */
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 36ca0d6..bc77f80 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -3048,8 +3048,8 @@
 
         MBEDTLS_SSL_DEBUG_MSG( 2, ( "ECDHE curve: %s", (*curve)->name ) );
 
-        if( ( ret = mbedtls_ecp_group_load( &ssl->handshake->ecdh_ctx.grp,
-                                       (*curve)->grp_id ) ) != 0 )
+        if( ( ret = mbedtls_ecdh_setup( &ssl->handshake->ecdh_ctx,
+                                        (*curve)->grp_id ) ) != 0 )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecp_group_load", ret );
             return( ret );
@@ -3071,7 +3071,8 @@
 
         ssl->out_msglen += len;
 
-        MBEDTLS_SSL_DEBUG_ECP( 3, "ECDH: Q ", &ssl->handshake->ecdh_ctx.Q );
+        MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
+                                MBEDTLS_DEBUG_ECDH_Q );
     }
 #endif /* MBEDTLS_KEY_EXCHANGE__SOME__ECDHE_ENABLED */
 
@@ -3794,7 +3795,8 @@
             return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE_RP );
         }
 
-        MBEDTLS_SSL_DEBUG_ECP( 3, "ECDH: Qp ", &ssl->handshake->ecdh_ctx.Qp );
+        MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
+                                MBEDTLS_DEBUG_ECDH_QP );
 
         if( ( ret = mbedtls_ecdh_calc_secret( &ssl->handshake->ecdh_ctx,
                                       &ssl->handshake->pmslen,
@@ -3806,7 +3808,8 @@
             return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE_CS );
         }
 
-        MBEDTLS_SSL_DEBUG_MPI( 3, "ECDH: z  ", &ssl->handshake->ecdh_ctx.z );
+        MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
+                                MBEDTLS_DEBUG_ECDH_Z );
     }
     else
 #endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED ||
@@ -3919,7 +3922,8 @@
             return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE_RP );
         }
 
-        MBEDTLS_SSL_DEBUG_ECP( 3, "ECDH: Qp ", &ssl->handshake->ecdh_ctx.Qp );
+        MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
+                                MBEDTLS_DEBUG_ECDH_QP );
 
         if( ( ret = mbedtls_ssl_psk_derive_premaster( ssl,
                         ciphersuite_info->key_exchange ) ) != 0 )
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 82e6525..c64036c 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1333,7 +1333,8 @@
         *(p++) = (unsigned char)( zlen      );
         p += zlen;
 
-        MBEDTLS_SSL_DEBUG_MPI( 3, "ECDH: z", &ssl->handshake->ecdh_ctx.z );
+        MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
+                                MBEDTLS_DEBUG_ECDH_Z );
     }
     else
 #endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED */
diff --git a/programs/pkey/ecdh_curve25519.c b/programs/pkey/ecdh_curve25519.c
index 5db0408..7fbf167 100644
--- a/programs/pkey/ecdh_curve25519.c
+++ b/programs/pkey/ecdh_curve25519.c
@@ -35,12 +35,12 @@
 #define MBEDTLS_EXIT_FAILURE    EXIT_FAILURE
 #endif /* MBEDTLS_PLATFORM_C */
 
-#if !defined(MBEDTLS_ECDH_C) || \
+#if !defined(MBEDTLS_ECDH_C) || !defined(MBEDTLS_ECDH_LEGACY_CONTEXT) || \
     !defined(MBEDTLS_ECP_DP_CURVE25519_ENABLED) || \
     !defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_CTR_DRBG_C)
 int main( void )
 {
-    mbedtls_printf( "MBEDTLS_ECDH_C and/or "
+    mbedtls_printf( "MBEDTLS_ECDH_C and/or MBEDTLS_ECDH_LEGACY_CONTEXT and/or "
                     "MBEDTLS_ECP_DP_CURVE25519_ENABLED and/or "
                     "MBEDTLS_ENTROPY_C and/or MBEDTLS_CTR_DRBG_C "
                     "not defined\n" );
diff --git a/programs/test/benchmark.c b/programs/test/benchmark.c
index e7d29c3..dd4303b 100644
--- a/programs/test/benchmark.c
+++ b/programs/test/benchmark.c
@@ -862,7 +862,7 @@
     }
 #endif
 
-#if defined(MBEDTLS_ECDH_C)
+#if defined(MBEDTLS_ECDH_C) && defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
     if( todo.ecdh )
     {
         mbedtls_ecdh_context ecdh;
diff --git a/tests/suites/test_suite_ecdh.data b/tests/suites/test_suite_ecdh.data
index 0165a7e..89e5e3a 100644
--- a/tests/suites/test_suite_ecdh.data
+++ b/tests/suites/test_suite_ecdh.data
@@ -69,3 +69,7 @@
 ECDH restartable rfc 5903 p256 restart disabled max_ops=250
 depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
 ecdh_restart:MBEDTLS_ECP_DP_SECP256R1:"C88F01F510D9AC3F70A292DAA2316DE544E9AAB8AFE84049C62A9C57862D1433":"C6EF9C5D78AE012A011164ACB397CE2088685D8F06BF9BE0B283AB46476BEE53":"D6840F6B42F6EDAFD13116E0E12565202FEF8E9ECE7DCE03812464D04B9442DE":0:250:0:0
+
+ECDH exchange legacy context
+depends_on:MBEDTLS_ECP_DP_SECP192R1_ENABLED
+ecdh_exchange_legacy:MBEDTLS_ECP_DP_SECP192R1
diff --git a/tests/suites/test_suite_ecdh.function b/tests/suites/test_suite_ecdh.function
index 9652308..7144763 100644
--- a/tests/suites/test_suite_ecdh.function
+++ b/tests/suites/test_suite_ecdh.function
@@ -129,27 +129,31 @@
     const unsigned char *vbuf;
     size_t len;
     rnd_pseudo_info rnd_info;
+    unsigned char res_buf[1000];
+    size_t res_len;
 
     mbedtls_ecdh_init( &srv );
     mbedtls_ecdh_init( &cli );
     memset( &rnd_info, 0x00, sizeof( rnd_pseudo_info ) );
 
-    TEST_ASSERT( mbedtls_ecp_group_load( &srv.grp, id ) == 0 );
+    TEST_ASSERT( mbedtls_ecdh_setup( &srv, id ) == 0 );
 
     memset( buf, 0x00, sizeof( buf ) ); vbuf = buf;
     TEST_ASSERT( mbedtls_ecdh_make_params( &srv, &len, buf, 1000,
-                                   &rnd_pseudo_rand, &rnd_info ) == 0 );
+                                           &rnd_pseudo_rand, &rnd_info ) == 0 );
     TEST_ASSERT( mbedtls_ecdh_read_params( &cli, &vbuf, buf + len ) == 0 );
 
     memset( buf, 0x00, sizeof( buf ) );
     TEST_ASSERT( mbedtls_ecdh_make_public( &cli, &len, buf, 1000,
-                                   &rnd_pseudo_rand, &rnd_info ) == 0 );
+                                           &rnd_pseudo_rand, &rnd_info ) == 0 );
     TEST_ASSERT( mbedtls_ecdh_read_public( &srv, buf, len ) == 0 );
 
     TEST_ASSERT( mbedtls_ecdh_calc_secret( &srv, &len, buf, 1000,
-                                   &rnd_pseudo_rand, &rnd_info ) == 0 );
-    TEST_ASSERT( mbedtls_ecdh_calc_secret( &cli, &len, buf, 1000, NULL, NULL ) == 0 );
-    TEST_ASSERT( mbedtls_mpi_cmp_mpi( &srv.z, &cli.z ) == 0 );
+                                           &rnd_pseudo_rand, &rnd_info ) == 0 );
+    TEST_ASSERT( mbedtls_ecdh_calc_secret( &cli, &res_len, res_buf, 1000,
+                                           NULL, NULL ) == 0 );
+    TEST_ASSERT( len == res_len );
+    TEST_ASSERT( memcmp( buf, res_buf, len ) == 0 );
 
 exit:
     mbedtls_ecdh_free( &srv );
@@ -172,7 +176,9 @@
     unsigned char rnd_buf_B[MBEDTLS_ECP_MAX_BYTES];
     rnd_buf_info rnd_info_A, rnd_info_B;
     int cnt_restart;
+    mbedtls_ecp_group grp;
 
+    mbedtls_ecp_group_init( &grp );
     mbedtls_ecdh_init( &srv );
     mbedtls_ecdh_init( &cli );
 
@@ -184,16 +190,20 @@
     rnd_info_B.buf = rnd_buf_B;
     rnd_info_B.length = unhexify( rnd_buf_B, dB_str );
 
-    TEST_ASSERT( mbedtls_ecp_group_load( &srv.grp, id ) == 0 );
+    /* The ECDH context is not guaranteed ot have an mbedtls_ecp_group structure
+     * in every configuration, therefore we load it separately. */
+    TEST_ASSERT( mbedtls_ecp_group_load( &grp, id ) == 0 );
 
-    /* otherwise we would have to fix the random buffer,
-     * as in ecdh_primitive_test_vec */
-    TEST_ASSERT( srv.grp.nbits % 8 == 0 );
+    /* Otherwise we would have to fix the random buffer,
+     * as in ecdh_primitive_testvec. */
+    TEST_ASSERT( grp.nbits % 8 == 0 );
+
+    TEST_ASSERT( mbedtls_ecdh_setup( &srv, id ) == 0 );
 
     /* set up restart parameters */
     mbedtls_ecp_set_max_ops( max_ops );
 
-    if( enable)
+    if( enable )
     {
         mbedtls_ecdh_enable_restart( &srv );
         mbedtls_ecdh_enable_restart( &cli );
@@ -269,6 +279,45 @@
     TEST_ASSERT( memcmp( buf, z, len ) == 0 );
 
 exit:
+    mbedtls_ecp_group_free( &grp );
+    mbedtls_ecdh_free( &srv );
+    mbedtls_ecdh_free( &cli );
+}
+/* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_ECDH_LEGACY_CONTEXT */
+void ecdh_exchange_legacy( int id )
+{
+    mbedtls_ecdh_context srv, cli;
+    unsigned char buf[1000];
+    const unsigned char *vbuf;
+    size_t len;
+
+    rnd_pseudo_info rnd_info;
+
+    mbedtls_ecdh_init( &srv );
+    mbedtls_ecdh_init( &cli );
+    memset( &rnd_info, 0x00, sizeof( rnd_pseudo_info ) );
+
+    TEST_ASSERT( mbedtls_ecp_group_load( &srv.grp, id ) == 0 );
+
+    memset( buf, 0x00, sizeof( buf ) ); vbuf = buf;
+    TEST_ASSERT( mbedtls_ecdh_make_params( &srv, &len, buf, 1000,
+                                   &rnd_pseudo_rand, &rnd_info ) == 0 );
+    TEST_ASSERT( mbedtls_ecdh_read_params( &cli, &vbuf, buf + len ) == 0 );
+
+    memset( buf, 0x00, sizeof( buf ) );
+    TEST_ASSERT( mbedtls_ecdh_make_public( &cli, &len, buf, 1000,
+                                           &rnd_pseudo_rand, &rnd_info ) == 0 );
+    TEST_ASSERT( mbedtls_ecdh_read_public( &srv, buf, len ) == 0 );
+
+    TEST_ASSERT( mbedtls_ecdh_calc_secret( &srv, &len, buf, 1000,
+                                           &rnd_pseudo_rand, &rnd_info ) == 0 );
+    TEST_ASSERT( mbedtls_ecdh_calc_secret( &cli, &len, buf, 1000, NULL,
+                                           NULL ) == 0 );
+    TEST_ASSERT( mbedtls_mpi_cmp_mpi( &srv.z, &cli.z ) == 0 );
+
+exit:
     mbedtls_ecdh_free( &srv );
     mbedtls_ecdh_free( &cli );
 }