Add ecdh_{make,read}_public()

include/polarssl/ecdh.h

@@ -122,6 +122,33 @@ int ecdh_make_params( ecdh_context *ctx, size_t *olen,
 int ecdh_read_params( ecdh_context *ctx,
                       const unsigned char **buf, const unsigned char *end );
 
+/**
+ * \brief           Setup and export the client's public value
+ *
+ * \param ctx       ECDH context
+ * \param olen      number of bytes actually written
+ * \param buf       destination buffer
+ * \param blen      size of destination buffer
+ *
+ * \return          0 if successful, or an POLARSSL_ERR_ECP_XXX error code
+ */
+int ecdh_make_public( 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 and import the client's public value
+ *
+ * \param ctx       ECDH context
+ * \param buf       start of input buffer
+ * \param blen      length of input buffer
+ *
+ * \return          0 if successful, or an POLARSSL_ERR_ECP_XXX error code
+ */
+int ecdh_read_public( ecdh_context *ctx,
+                      const unsigned char *buf, size_t blen );
+
 /**
  * \brief          Checkup routine
  *

library/ecdh.c

@@ -159,6 +159,33 @@ int ecdh_read_params( ecdh_context *ctx,
     return 0;
 }
 
+/*
+ * Setup and export the client public value
+ */
+int ecdh_make_public( 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;
+
+    if( ( ret = ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) )
+                != 0 )
+        return( ret );
+
+    return ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format,
+                                olen, buf, blen );
+}
+
+/*
+ * Parse and import the client's public value
+ */
+int ecdh_read_public( ecdh_context *ctx,
+                      const unsigned char *buf, size_t blen )
+{
+    return ecp_tls_read_point( &ctx->grp, &ctx->Qp, &buf, blen );
+}
+
 #if defined(POLARSSL_SELF_TEST)
 
 /*

tests/suites/test_suite_ecdh.function

@@ -99,6 +99,11 @@ ecdh_exchange:id
                                    &rnd_pseudo_rand, &rnd_info ) == 0 );
     TEST_ASSERT( ecdh_read_params( &cli, &vbuf, buf + len ) == 0 );
 
+    memset( buf, 0x00, sizeof( buf ) ); vbuf = buf;
+    TEST_ASSERT( ecdh_make_public( &cli, &len, buf, 1000,
+                                   &rnd_pseudo_rand, &rnd_info ) == 0 );
+    TEST_ASSERT( ecdh_read_public( &srv, buf, len ) == 0 );
+
     ecdh_free( &srv );
     ecdh_free( &cli );
 }