Add ecdh_get_params() to import from an EC key
diff --git a/include/polarssl/ecdh.h b/include/polarssl/ecdh.h
index 4c82f25..d20f9bf 100644
--- a/include/polarssl/ecdh.h
+++ b/include/polarssl/ecdh.h
@@ -34,6 +34,15 @@
#endif
/**
+ * When importing from an EC key, select if it is our key or the peer's key
+ */
+typedef enum
+{
+ POLARSSL_ECDH_OURS,
+ POLARSSL_ECDH_THEIRS,
+} ecdh_side;
+
+/**
* \brief ECDH context structure
*/
typedef struct
@@ -135,6 +144,18 @@
const unsigned char **buf, const unsigned char *end );
/**
+ * \brief Setup an ECDH context from an EC key
+ *
+ * \param ctx ECDH constext to set
+ * \param key EC key to use
+ * \param ours Is it our key (1) or the peer's key (0) ?
+ *
+ * \return 0 if successful, or an POLARSSL_ERR_ECP_XXX error code
+ */
+int ecdh_get_params( ecdh_context *ctx, const ecp_keypair *key,
+ ecdh_side side );
+
+/**
* \brief Setup and export the client's public value
*
* \param ctx ECDH context
diff --git a/library/ecdh.c b/library/ecdh.c
index 400e45f..302531d 100644
--- a/library/ecdh.c
+++ b/library/ecdh.c
@@ -166,6 +166,32 @@
}
/*
+ * Get parameters from a keypair
+ */
+int ecdh_get_params( ecdh_context *ctx, const ecp_keypair *key,
+ ecdh_side side )
+{
+ int ret;
+
+ if( ( ret = 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 == POLARSSL_ECDH_THEIRS )
+ return( ecp_copy( &ctx->Qp, &key->Q ) );
+
+ /* Our key: import public (as Q) and private parts */
+ if( side != POLARSSL_ECDH_OURS )
+ return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
+
+ if( ( ret = ecp_copy( &ctx->Q, &key->Q ) ) != 0 ||
+ ( ret = mpi_copy( &ctx->d, &key->d ) ) != 0 )
+ return( ret );
+
+ return( 0 );
+}
+
+/*
* Setup and export the client public value
*/
int ecdh_make_public( ecdh_context *ctx, size_t *olen,