Add ecdh_read_params().

include/polarssl/ecdh.h

@@ -105,11 +105,23 @@ void ecdh_free( ecdh_context *ctx );
  *
  * \return          0 if successful, or an POLARSSL_ERR_ECP_XXX error code
  */
-int ecdh_make_server_params( ecdh_context *ctx, size_t *olen,
+int ecdh_make_params( ecdh_context *ctx, size_t *olen,
                       unsigned char *buf, size_t blen,
                       int (*f_rng)(void *, unsigned char *, size_t),
                       void *p_rng );
 
+/**
+ * \brief           Parse the ServerKeyExhange parameters
+ *
+ * \param ctx       ECDH context
+ * \param buf       $(start of input buffer)
+ * \param end       one past end of buffer
+ *
+ * \return          0 if successful, or an POLARSSL_ERR_ECP_XXX error code
+ */
+int ecdh_read_params( ecdh_context *ctx,
+                      const unsigned char **buf, const unsigned char *end );
+
 /**
  * \brief          Checkup routine
  *

library/ecdh.c

@@ -104,13 +104,13 @@ void ecdh_free( ecdh_context *ctx )
 }
 
 /*
- * Setup and write the ServerKeyExhange parameters
+ * Setup and write the ServerKeyExhange parameters (RFC 4492)
  *      struct {
  *          ECParameters    curve_params;
  *          ECPoint         public;
  *      } ServerECDHParams;
  */
-int ecdh_make_server_params( ecdh_context *ctx, size_t *olen,
+int ecdh_make_params( ecdh_context *ctx, size_t *olen,
                       unsigned char *buf, size_t blen,
                       int (*f_rng)(void *, unsigned char *, size_t),
                       void *p_rng )
@@ -137,6 +137,27 @@ int ecdh_make_server_params( ecdh_context *ctx, size_t *olen,
     return 0;
 }
 
+/*
+ * Read the ServerKeyExhange parameters (RFC 4492)
+ *      struct {
+ *          ECParameters    curve_params;
+ *          ECPoint         public;
+ *      } ServerECDHParams;
+ */
+int ecdh_read_params( ecdh_context *ctx,
+                      const unsigned char **buf, const unsigned char *end )
+{
+    int ret;
+
+    if( ( ret = ecp_tls_read_group( &ctx->grp, buf, end - *buf ) ) != 0 )
+        return( ret );
+
+    if( ( ret = ecp_tls_read_point( &ctx->grp, &ctx->Qp, buf, end - *buf ) )
+                != 0 )
+        return( ret );
+
+    return 0;
+}
 
 #if defined(POLARSSL_SELF_TEST)
 

tests/suites/test_suite_ecdh.data

@@ -21,3 +21,9 @@ ecdh_primitive_testvec:SECP384R1:099F3C7034D4A2C699884D73A375A67F7624EF7C6B3C0F1
 
 ECDH primitive rfc 5903 p521
 ecdh_primitive_testvec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
+
+ECDH exchange #1
+ecdh_exchange:SECP192R1
+
+ECDH exchange #2
+ecdh_exchange:SECP521R1

tests/suites/test_suite_ecdh.function

@@ -78,3 +78,28 @@ ecdh_primitive_testvec:id:dA:xA:yA:dB:xB:yB:z
     mpi_free( &zA ); mpi_free( &zB ); mpi_free( &check );
 }
 END_CASE
+
+BEGIN_CASE
+ecdh_exchange:id
+{
+    ecdh_context srv, cli;
+    unsigned char buf[1000];
+    const unsigned char *vbuf;
+    size_t len;
+    rnd_pseudo_info rnd_info;
+
+    ecdh_init( &srv );
+    ecdh_init( &cli );
+    memset( &rnd_info, 0x00, sizeof( rnd_pseudo_info ) );
+
+    TEST_ASSERT( ecp_use_known_dp( &srv.grp, POLARSSL_ECP_DP_{id} ) == 0 );
+
+    memset( buf, 0x00, sizeof( buf ) ); vbuf = buf;
+    TEST_ASSERT( ecdh_make_params( &srv, &len, buf, 1000,
+                                   &rnd_pseudo_rand, &rnd_info ) == 0 );
+    TEST_ASSERT( ecdh_read_params( &cli, &vbuf, buf + len ) == 0 );
+
+    ecdh_free( &srv );
+    ecdh_free( &cli );
+}
+END_CASE