diff --git a/include/mbedtls/ecdh.h b/include/mbedtls/ecdh.h index 27f2ffc6a..68a6989c8 100644 --- a/include/mbedtls/ecdh.h +++ b/include/mbedtls/ecdh.h @@ -134,6 +134,24 @@ int mbedtls_ecdh_compute_shared( mbedtls_ecp_group *grp, mbedtls_mpi *z, */ 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. * @@ -145,8 +163,8 @@ void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx ); * \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 +260,9 @@ int mbedtls_ecdh_make_public( mbedtls_ecdh_context *ctx, size_t *olen, * \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/library/ecdh.c b/library/ecdh.c index e6ae99994..702ba1a40 100644 --- a/library/ecdh.c +++ b/library/ecdh.c @@ -145,6 +145,23 @@ void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx ) #endif } +/* + * Setup context + */ +int mbedtls_ecdh_setup( mbedtls_ecdh_context *ctx, mbedtls_ecp_group_id grp_id ) +{ + int ret; + + ret = mbedtls_ecp_group_load( &ctx->grp, grp_id ); + if( ret != 0 ) + { + mbedtls_ecdh_free( ctx ); + return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE ); + } + + return( 0 ); +} + /* * Free context */ @@ -240,12 +257,17 @@ int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx, 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( ( 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 ); + + if( ( ret = mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, buf, + end - *buf ) ) != 0 ) return( ret ); return( 0 ); @@ -259,7 +281,7 @@ int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx, const mbedtls_ecp_keypai { int ret; - if( ( ret = mbedtls_ecp_group_copy( &ctx->grp, &key->grp ) ) != 0 ) + if( ( ret = mbedtls_ecdh_setup( ctx, key->grp.id ) ) != 0 ) return( ret ); /* If it's not our key, just import the public part as Qp */