653 lines
20 KiB
C
653 lines
20 KiB
C
/*
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* Elliptic curve Diffie-Hellman
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*
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* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* This file is part of mbed TLS (https://tls.mbed.org)
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*/
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/*
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* References:
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*
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* SEC1 http://www.secg.org/index.php?action=secg,docs_secg
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* RFC 4492
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*/
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#if !defined(MBEDTLS_CONFIG_FILE)
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#include "mbedtls/config.h"
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#else
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#include MBEDTLS_CONFIG_FILE
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#endif
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#if defined(MBEDTLS_ECDH_C)
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#include "mbedtls/ecdh.h"
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#include "mbedtls/platform_util.h"
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#include <string.h>
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/* Parameter validation macros based on platform_util.h */
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#define ECDH_VALIDATE_RET( cond ) \
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MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_ECP_BAD_INPUT_DATA )
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#define ECDH_VALIDATE( cond ) \
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MBEDTLS_INTERNAL_VALIDATE( cond )
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#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
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typedef mbedtls_ecdh_context mbedtls_ecdh_context_mbed;
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#endif
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#if !defined(MBEDTLS_ECDH_GEN_PUBLIC_ALT)
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/*
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* Generate public key (restartable version)
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*
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* Note: this internal function relies on its caller preserving the value of
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* the output parameter 'd' across continuation calls. This would not be
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* acceptable for a public function but is OK here as we control call sites.
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*/
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static int ecdh_gen_public_restartable( mbedtls_ecp_group *grp,
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mbedtls_mpi *d, mbedtls_ecp_point *Q,
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int (*f_rng)(void *, unsigned char *, size_t),
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void *p_rng,
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mbedtls_ecp_restart_ctx *rs_ctx )
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{
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int ret;
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/* If multiplication is in progress, we already generated a privkey */
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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if( rs_ctx == NULL || rs_ctx->rsm == NULL )
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#endif
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MBEDTLS_MPI_CHK( mbedtls_ecp_gen_privkey( grp, d, f_rng, p_rng ) );
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MBEDTLS_MPI_CHK( mbedtls_ecp_mul_restartable( grp, Q, d, &grp->G,
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f_rng, p_rng, rs_ctx ) );
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cleanup:
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return( ret );
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}
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/*
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* Generate public key
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*/
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int mbedtls_ecdh_gen_public( mbedtls_ecp_group *grp, mbedtls_mpi *d, mbedtls_ecp_point *Q,
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int (*f_rng)(void *, unsigned char *, size_t),
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void *p_rng )
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{
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ECDH_VALIDATE_RET( grp != NULL );
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ECDH_VALIDATE_RET( d != NULL );
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ECDH_VALIDATE_RET( Q != NULL );
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ECDH_VALIDATE_RET( f_rng != NULL );
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return( ecdh_gen_public_restartable( grp, d, Q, f_rng, p_rng, NULL ) );
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}
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#endif /* !MBEDTLS_ECDH_GEN_PUBLIC_ALT */
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#if !defined(MBEDTLS_ECDH_COMPUTE_SHARED_ALT)
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/*
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* Compute shared secret (SEC1 3.3.1)
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*/
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static int ecdh_compute_shared_restartable( mbedtls_ecp_group *grp,
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mbedtls_mpi *z,
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const mbedtls_ecp_point *Q, const mbedtls_mpi *d,
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int (*f_rng)(void *, unsigned char *, size_t),
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void *p_rng,
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mbedtls_ecp_restart_ctx *rs_ctx )
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{
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int ret;
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mbedtls_ecp_point P;
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mbedtls_ecp_point_init( &P );
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MBEDTLS_MPI_CHK( mbedtls_ecp_mul_restartable( grp, &P, d, Q,
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f_rng, p_rng, rs_ctx ) );
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if( mbedtls_ecp_is_zero( &P ) )
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{
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ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
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goto cleanup;
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}
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MBEDTLS_MPI_CHK( mbedtls_mpi_copy( z, &P.X ) );
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cleanup:
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mbedtls_ecp_point_free( &P );
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return( ret );
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}
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/*
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* Compute shared secret (SEC1 3.3.1)
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*/
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int mbedtls_ecdh_compute_shared( mbedtls_ecp_group *grp, mbedtls_mpi *z,
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const mbedtls_ecp_point *Q, const mbedtls_mpi *d,
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int (*f_rng)(void *, unsigned char *, size_t),
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void *p_rng )
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{
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ECDH_VALIDATE_RET( grp != NULL );
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ECDH_VALIDATE_RET( Q != NULL );
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ECDH_VALIDATE_RET( d != NULL );
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ECDH_VALIDATE_RET( z != NULL );
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return( ecdh_compute_shared_restartable( grp, z, Q, d,
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f_rng, p_rng, NULL ) );
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}
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#endif /* !MBEDTLS_ECDH_COMPUTE_SHARED_ALT */
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static void ecdh_init_internal( mbedtls_ecdh_context_mbed *ctx )
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{
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mbedtls_ecp_group_init( &ctx->grp );
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mbedtls_mpi_init( &ctx->d );
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mbedtls_ecp_point_init( &ctx->Q );
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mbedtls_ecp_point_init( &ctx->Qp );
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mbedtls_mpi_init( &ctx->z );
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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mbedtls_ecp_restart_init( &ctx->rs );
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#endif
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}
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/*
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* Initialize context
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*/
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void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx )
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{
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ECDH_VALIDATE( ctx != NULL );
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#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
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ecdh_init_internal( ctx );
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mbedtls_ecp_point_init( &ctx->Vi );
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mbedtls_ecp_point_init( &ctx->Vf );
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mbedtls_mpi_init( &ctx->_d );
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#else
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memset( ctx, 0, sizeof( mbedtls_ecdh_context ) );
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ctx->var = MBEDTLS_ECDH_VARIANT_NONE;
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#endif
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ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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ctx->restart_enabled = 0;
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#endif
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}
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static int ecdh_setup_internal( mbedtls_ecdh_context_mbed *ctx,
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mbedtls_ecp_group_id grp_id )
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{
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int ret;
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ret = mbedtls_ecp_group_load( &ctx->grp, grp_id );
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if( ret != 0 )
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{
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return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
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}
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return( 0 );
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}
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/*
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* Setup context
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*/
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int mbedtls_ecdh_setup( mbedtls_ecdh_context *ctx, mbedtls_ecp_group_id grp_id )
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{
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ECDH_VALIDATE_RET( ctx != NULL );
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#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
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return( ecdh_setup_internal( ctx, grp_id ) );
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#else
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switch( grp_id )
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{
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default:
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ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
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ctx->var = MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0;
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ctx->grp_id = grp_id;
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ecdh_init_internal( &ctx->ctx.mbed_ecdh );
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return( ecdh_setup_internal( &ctx->ctx.mbed_ecdh, grp_id ) );
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}
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#endif
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}
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static void ecdh_free_internal( mbedtls_ecdh_context_mbed *ctx )
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{
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mbedtls_ecp_group_free( &ctx->grp );
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mbedtls_mpi_free( &ctx->d );
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mbedtls_ecp_point_free( &ctx->Q );
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mbedtls_ecp_point_free( &ctx->Qp );
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mbedtls_mpi_free( &ctx->z );
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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mbedtls_ecp_restart_free( &ctx->rs );
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#endif
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}
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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/*
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* Enable restartable operations for context
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*/
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void mbedtls_ecdh_enable_restart( mbedtls_ecdh_context *ctx )
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{
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ECDH_VALIDATE( ctx != NULL );
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ctx->restart_enabled = 1;
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}
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#endif
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/*
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* Free context
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*/
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void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx )
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{
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if( ctx == NULL )
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return;
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#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
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mbedtls_ecp_point_free( &ctx->Vi );
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mbedtls_ecp_point_free( &ctx->Vf );
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mbedtls_mpi_free( &ctx->_d );
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ecdh_free_internal( ctx );
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#else
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switch( ctx->var )
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{
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case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
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ecdh_free_internal( &ctx->ctx.mbed_ecdh );
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break;
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default:
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break;
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}
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ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
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ctx->var = MBEDTLS_ECDH_VARIANT_NONE;
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ctx->grp_id = MBEDTLS_ECP_DP_NONE;
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#endif
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}
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static int ecdh_make_params_internal( mbedtls_ecdh_context_mbed *ctx,
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size_t *olen, int point_format,
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unsigned char *buf, size_t blen,
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int (*f_rng)(void *,
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unsigned char *,
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size_t),
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void *p_rng,
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int restart_enabled )
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{
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int ret;
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size_t grp_len, pt_len;
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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mbedtls_ecp_restart_ctx *rs_ctx = NULL;
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#endif
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if( ctx->grp.pbits == 0 )
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return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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if( restart_enabled )
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rs_ctx = &ctx->rs;
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#else
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(void) restart_enabled;
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#endif
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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if( ( ret = ecdh_gen_public_restartable( &ctx->grp, &ctx->d, &ctx->Q,
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f_rng, p_rng, rs_ctx ) ) != 0 )
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return( ret );
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#else
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if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q,
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f_rng, p_rng ) ) != 0 )
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return( ret );
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#endif /* MBEDTLS_ECP_RESTARTABLE */
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if( ( ret = mbedtls_ecp_tls_write_group( &ctx->grp, &grp_len, buf,
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blen ) ) != 0 )
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return( ret );
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buf += grp_len;
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blen -= grp_len;
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if( ( ret = mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, point_format,
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&pt_len, buf, blen ) ) != 0 )
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return( ret );
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*olen = grp_len + pt_len;
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return( 0 );
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}
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/*
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* Setup and write the ServerKeyExhange parameters (RFC 4492)
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* struct {
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* ECParameters curve_params;
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* ECPoint public;
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* } ServerECDHParams;
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*/
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int mbedtls_ecdh_make_params( mbedtls_ecdh_context *ctx, size_t *olen,
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unsigned char *buf, size_t blen,
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int (*f_rng)(void *, unsigned char *, size_t),
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void *p_rng )
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{
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int restart_enabled = 0;
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ECDH_VALIDATE_RET( ctx != NULL );
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ECDH_VALIDATE_RET( olen != NULL );
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ECDH_VALIDATE_RET( buf != NULL );
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ECDH_VALIDATE_RET( f_rng != NULL );
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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restart_enabled = ctx->restart_enabled;
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#else
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(void) restart_enabled;
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#endif
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#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
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return( ecdh_make_params_internal( ctx, olen, ctx->point_format, buf, blen,
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f_rng, p_rng, restart_enabled ) );
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#else
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switch( ctx->var )
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{
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case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
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return( ecdh_make_params_internal( &ctx->ctx.mbed_ecdh, olen,
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ctx->point_format, buf, blen,
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f_rng, p_rng,
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restart_enabled ) );
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default:
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return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
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}
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#endif
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}
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static int ecdh_read_params_internal( mbedtls_ecdh_context_mbed *ctx,
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const unsigned char **buf,
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const unsigned char *end )
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{
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return( mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, buf,
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end - *buf ) );
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}
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/*
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* Read the ServerKeyExhange parameters (RFC 4492)
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* struct {
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* ECParameters curve_params;
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* ECPoint public;
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* } ServerECDHParams;
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*/
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int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx,
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const unsigned char **buf,
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const unsigned char *end )
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{
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int ret;
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mbedtls_ecp_group_id grp_id;
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ECDH_VALIDATE_RET( ctx != NULL );
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ECDH_VALIDATE_RET( buf != NULL );
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ECDH_VALIDATE_RET( *buf != NULL );
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ECDH_VALIDATE_RET( end != NULL );
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if( ( ret = mbedtls_ecp_tls_read_group_id( &grp_id, buf, end - *buf ) )
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!= 0 )
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return( ret );
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if( ( ret = mbedtls_ecdh_setup( ctx, grp_id ) ) != 0 )
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return( ret );
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#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
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return( ecdh_read_params_internal( ctx, buf, end ) );
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#else
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switch( ctx->var )
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{
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case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
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return( ecdh_read_params_internal( &ctx->ctx.mbed_ecdh,
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buf, end ) );
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default:
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return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
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}
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#endif
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}
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static int ecdh_get_params_internal( mbedtls_ecdh_context_mbed *ctx,
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const mbedtls_ecp_keypair *key,
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mbedtls_ecdh_side side )
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{
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int ret;
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/* If it's not our key, just import the public part as Qp */
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if( side == MBEDTLS_ECDH_THEIRS )
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return( mbedtls_ecp_copy( &ctx->Qp, &key->Q ) );
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/* Our key: import public (as Q) and private parts */
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if( side != MBEDTLS_ECDH_OURS )
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return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
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if( ( ret = mbedtls_ecp_copy( &ctx->Q, &key->Q ) ) != 0 ||
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( ret = mbedtls_mpi_copy( &ctx->d, &key->d ) ) != 0 )
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return( ret );
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return( 0 );
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}
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/*
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* Get parameters from a keypair
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*/
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int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx,
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const mbedtls_ecp_keypair *key,
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mbedtls_ecdh_side side )
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{
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int ret;
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ECDH_VALIDATE_RET( ctx != NULL );
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ECDH_VALIDATE_RET( key != NULL );
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ECDH_VALIDATE_RET( side == MBEDTLS_ECDH_OURS ||
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side == MBEDTLS_ECDH_THEIRS );
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if( ( ret = mbedtls_ecdh_setup( ctx, key->grp.id ) ) != 0 )
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return( ret );
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#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
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return( ecdh_get_params_internal( ctx, key, side ) );
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#else
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switch( ctx->var )
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{
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case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
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return( ecdh_get_params_internal( &ctx->ctx.mbed_ecdh,
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key, side ) );
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default:
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return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
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}
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#endif
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}
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static int ecdh_make_public_internal( mbedtls_ecdh_context_mbed *ctx,
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size_t *olen, int point_format,
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unsigned char *buf, size_t blen,
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int (*f_rng)(void *,
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unsigned char *,
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size_t),
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void *p_rng,
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int restart_enabled )
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{
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int ret;
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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mbedtls_ecp_restart_ctx *rs_ctx = NULL;
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#endif
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if( ctx->grp.pbits == 0 )
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return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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if( restart_enabled )
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rs_ctx = &ctx->rs;
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#else
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(void) restart_enabled;
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#endif
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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if( ( ret = ecdh_gen_public_restartable( &ctx->grp, &ctx->d, &ctx->Q,
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f_rng, p_rng, rs_ctx ) ) != 0 )
|
|
return( ret );
|
|
#else
|
|
if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q,
|
|
f_rng, p_rng ) ) != 0 )
|
|
return( ret );
|
|
#endif /* MBEDTLS_ECP_RESTARTABLE */
|
|
|
|
return mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, point_format, olen,
|
|
buf, blen );
|
|
}
|
|
|
|
/*
|
|
* Setup and export the client public value
|
|
*/
|
|
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 restart_enabled = 0;
|
|
ECDH_VALIDATE_RET( ctx != NULL );
|
|
ECDH_VALIDATE_RET( olen != NULL );
|
|
ECDH_VALIDATE_RET( buf != NULL );
|
|
ECDH_VALIDATE_RET( f_rng != NULL );
|
|
|
|
#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 )
|
|
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
|
|
|
|
return( 0 );
|
|
}
|
|
|
|
/*
|
|
* Parse and import the client's public value
|
|
*/
|
|
int mbedtls_ecdh_read_public( mbedtls_ecdh_context *ctx,
|
|
const unsigned char *buf, size_t blen )
|
|
{
|
|
ECDH_VALIDATE_RET( ctx != NULL );
|
|
ECDH_VALIDATE_RET( buf != NULL );
|
|
|
|
#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)
|
|
mbedtls_ecp_restart_ctx *rs_ctx = NULL;
|
|
#endif
|
|
|
|
if( ctx == NULL || ctx->grp.pbits == 0 )
|
|
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
|
|
|
|
#if defined(MBEDTLS_ECP_RESTARTABLE)
|
|
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 )
|
|
{
|
|
return( ret );
|
|
}
|
|
#else
|
|
if( ( ret = mbedtls_ecdh_compute_shared( &ctx->grp, &ctx->z, &ctx->Qp,
|
|
&ctx->d, f_rng, p_rng ) ) != 0 )
|
|
{
|
|
return( ret );
|
|
}
|
|
#endif /* MBEDTLS_ECP_RESTARTABLE */
|
|
|
|
if( mbedtls_mpi_size( &ctx->z ) > blen )
|
|
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
|
|
|
|
*olen = ctx->grp.pbits / 8 + ( ( ctx->grp.pbits % 8 ) != 0 );
|
|
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;
|
|
ECDH_VALIDATE_RET( ctx != NULL );
|
|
ECDH_VALIDATE_RET( olen != NULL );
|
|
ECDH_VALIDATE_RET( buf != NULL );
|
|
|
|
#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 */
|