diff options
Diffstat (limited to 'lib/mbedtls-2.27.0/library/ecdh.c')
| -rw-r--r-- | lib/mbedtls-2.27.0/library/ecdh.c | 729 |
1 files changed, 729 insertions, 0 deletions
diff --git a/lib/mbedtls-2.27.0/library/ecdh.c b/lib/mbedtls-2.27.0/library/ecdh.c new file mode 100644 index 0000000..9dfa868 --- /dev/null +++ b/lib/mbedtls-2.27.0/library/ecdh.c @@ -0,0 +1,729 @@ +/* + * Elliptic curve Diffie-Hellman + * + * Copyright The Mbed TLS Contributors + * SPDX-License-Identifier: Apache-2.0 + * + * Licensed under the Apache License, Version 2.0 (the "License"); you may + * not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +/* + * References: + * + * SEC1 http://www.secg.org/index.php?action=secg,docs_secg + * RFC 4492 + */ + +#include "common.h" + +#if defined(MBEDTLS_ECDH_C) + +#include "mbedtls/ecdh.h" +#include "mbedtls/platform_util.h" +#include "mbedtls/error.h" + +#include <string.h> + +/* Parameter validation macros based on platform_util.h */ +#define ECDH_VALIDATE_RET( cond ) \ + MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_ECP_BAD_INPUT_DATA ) +#define ECDH_VALIDATE( cond ) \ + MBEDTLS_INTERNAL_VALIDATE( cond ) + +#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT) +typedef mbedtls_ecdh_context mbedtls_ecdh_context_mbed; +#endif + +static mbedtls_ecp_group_id mbedtls_ecdh_grp_id( + const mbedtls_ecdh_context *ctx ) +{ +#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT) + return( ctx->grp.id ); +#else + return( ctx->grp_id ); +#endif +} + +int mbedtls_ecdh_can_do( mbedtls_ecp_group_id gid ) +{ + /* At this time, all groups support ECDH. */ + (void) gid; + return( 1 ); +} + +#if !defined(MBEDTLS_ECDH_GEN_PUBLIC_ALT) +/* + * Generate public key (restartable version) + * + * Note: this internal function relies on its caller preserving the value of + * the output parameter 'd' across continuation calls. This would not be + * acceptable for a public function but is OK here as we control call sites. + */ +static int ecdh_gen_public_restartable( mbedtls_ecp_group *grp, + mbedtls_mpi *d, mbedtls_ecp_point *Q, + int (*f_rng)(void *, unsigned char *, size_t), + void *p_rng, + mbedtls_ecp_restart_ctx *rs_ctx ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + /* If multiplication is in progress, we already generated a privkey */ +#if defined(MBEDTLS_ECP_RESTARTABLE) + if( rs_ctx == NULL || rs_ctx->rsm == NULL ) +#endif + MBEDTLS_MPI_CHK( mbedtls_ecp_gen_privkey( grp, d, f_rng, p_rng ) ); + + MBEDTLS_MPI_CHK( mbedtls_ecp_mul_restartable( grp, Q, d, &grp->G, + f_rng, p_rng, rs_ctx ) ); + +cleanup: + return( ret ); +} + +/* + * Generate public key + */ +int mbedtls_ecdh_gen_public( mbedtls_ecp_group *grp, mbedtls_mpi *d, mbedtls_ecp_point *Q, + int (*f_rng)(void *, unsigned char *, size_t), + void *p_rng ) +{ + ECDH_VALIDATE_RET( grp != NULL ); + ECDH_VALIDATE_RET( d != NULL ); + ECDH_VALIDATE_RET( Q != NULL ); + ECDH_VALIDATE_RET( f_rng != NULL ); + return( ecdh_gen_public_restartable( grp, d, Q, f_rng, p_rng, NULL ) ); +} +#endif /* !MBEDTLS_ECDH_GEN_PUBLIC_ALT */ + +#if !defined(MBEDTLS_ECDH_COMPUTE_SHARED_ALT) +/* + * Compute shared secret (SEC1 3.3.1) + */ +static int ecdh_compute_shared_restartable( mbedtls_ecp_group *grp, + mbedtls_mpi *z, + const mbedtls_ecp_point *Q, const mbedtls_mpi *d, + int (*f_rng)(void *, unsigned char *, size_t), + void *p_rng, + mbedtls_ecp_restart_ctx *rs_ctx ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + mbedtls_ecp_point P; + + mbedtls_ecp_point_init( &P ); + + MBEDTLS_MPI_CHK( mbedtls_ecp_mul_restartable( grp, &P, d, Q, + f_rng, p_rng, rs_ctx ) ); + + if( mbedtls_ecp_is_zero( &P ) ) + { + ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA; + goto cleanup; + } + + MBEDTLS_MPI_CHK( mbedtls_mpi_copy( z, &P.X ) ); + +cleanup: + mbedtls_ecp_point_free( &P ); + + return( ret ); +} + +/* + * Compute shared secret (SEC1 3.3.1) + */ +int mbedtls_ecdh_compute_shared( mbedtls_ecp_group *grp, mbedtls_mpi *z, + const mbedtls_ecp_point *Q, const mbedtls_mpi *d, + int (*f_rng)(void *, unsigned char *, size_t), + void *p_rng ) +{ + ECDH_VALIDATE_RET( grp != NULL ); + ECDH_VALIDATE_RET( Q != NULL ); + ECDH_VALIDATE_RET( d != NULL ); + ECDH_VALIDATE_RET( z != NULL ); + return( ecdh_compute_shared_restartable( grp, z, Q, d, + f_rng, p_rng, NULL ) ); +} +#endif /* !MBEDTLS_ECDH_COMPUTE_SHARED_ALT */ + +static void ecdh_init_internal( mbedtls_ecdh_context_mbed *ctx ) +{ + mbedtls_ecp_group_init( &ctx->grp ); + mbedtls_mpi_init( &ctx->d ); + mbedtls_ecp_point_init( &ctx->Q ); + mbedtls_ecp_point_init( &ctx->Qp ); + mbedtls_mpi_init( &ctx->z ); + +#if defined(MBEDTLS_ECP_RESTARTABLE) + mbedtls_ecp_restart_init( &ctx->rs ); +#endif +} + +/* + * Initialize context + */ +void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx ) +{ + ECDH_VALIDATE( ctx != NULL ); + +#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT) + ecdh_init_internal( ctx ); + mbedtls_ecp_point_init( &ctx->Vi ); + mbedtls_ecp_point_init( &ctx->Vf ); + mbedtls_mpi_init( &ctx->_d ); +#else + memset( ctx, 0, sizeof( mbedtls_ecdh_context ) ); + + ctx->var = MBEDTLS_ECDH_VARIANT_NONE; +#endif + ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED; +#if defined(MBEDTLS_ECP_RESTARTABLE) + ctx->restart_enabled = 0; +#endif +} + +static int ecdh_setup_internal( mbedtls_ecdh_context_mbed *ctx, + mbedtls_ecp_group_id grp_id ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + ret = mbedtls_ecp_group_load( &ctx->grp, grp_id ); + if( ret != 0 ) + { + return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE ); + } + + return( 0 ); +} + +/* + * Setup context + */ +int mbedtls_ecdh_setup( mbedtls_ecdh_context *ctx, mbedtls_ecp_group_id grp_id ) +{ + ECDH_VALIDATE_RET( ctx != NULL ); + +#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT) + return( ecdh_setup_internal( ctx, grp_id ) ); +#else + switch( grp_id ) + { +#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED) + case MBEDTLS_ECP_DP_CURVE25519: + ctx->point_format = MBEDTLS_ECP_PF_COMPRESSED; + ctx->var = MBEDTLS_ECDH_VARIANT_EVEREST; + ctx->grp_id = grp_id; + return( mbedtls_everest_setup( &ctx->ctx.everest_ecdh, grp_id ) ); +#endif + default: + ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED; + ctx->var = MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0; + ctx->grp_id = grp_id; + ecdh_init_internal( &ctx->ctx.mbed_ecdh ); + return( ecdh_setup_internal( &ctx->ctx.mbed_ecdh, grp_id ) ); + } +#endif +} + +static void ecdh_free_internal( mbedtls_ecdh_context_mbed *ctx ) +{ + mbedtls_ecp_group_free( &ctx->grp ); + mbedtls_mpi_free( &ctx->d ); + mbedtls_ecp_point_free( &ctx->Q ); + mbedtls_ecp_point_free( &ctx->Qp ); + mbedtls_mpi_free( &ctx->z ); + +#if defined(MBEDTLS_ECP_RESTARTABLE) + mbedtls_ecp_restart_free( &ctx->rs ); +#endif +} + +#if defined(MBEDTLS_ECP_RESTARTABLE) +/* + * Enable restartable operations for context + */ +void mbedtls_ecdh_enable_restart( mbedtls_ecdh_context *ctx ) +{ + ECDH_VALIDATE( ctx != NULL ); + + ctx->restart_enabled = 1; +} +#endif + +/* + * Free context + */ +void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx ) +{ + if( ctx == NULL ) + return; + +#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT) + mbedtls_ecp_point_free( &ctx->Vi ); + mbedtls_ecp_point_free( &ctx->Vf ); + mbedtls_mpi_free( &ctx->_d ); + ecdh_free_internal( ctx ); +#else + switch( ctx->var ) + { +#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED) + case MBEDTLS_ECDH_VARIANT_EVEREST: + mbedtls_everest_free( &ctx->ctx.everest_ecdh ); + break; +#endif + case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0: + ecdh_free_internal( &ctx->ctx.mbed_ecdh ); + break; + default: + break; + } + + ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED; + ctx->var = MBEDTLS_ECDH_VARIANT_NONE; + ctx->grp_id = MBEDTLS_ECP_DP_NONE; +#endif +} + +static int ecdh_make_params_internal( mbedtls_ecdh_context_mbed *ctx, + size_t *olen, int point_format, + unsigned char *buf, size_t blen, + int (*f_rng)(void *, + unsigned char *, + size_t), + void *p_rng, + int restart_enabled ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t grp_len, pt_len; +#if defined(MBEDTLS_ECP_RESTARTABLE) + mbedtls_ecp_restart_ctx *rs_ctx = NULL; +#endif + + if( 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_gen_public_restartable( &ctx->grp, &ctx->d, &ctx->Q, + 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 */ + + if( ( ret = mbedtls_ecp_tls_write_group( &ctx->grp, &grp_len, buf, + blen ) ) != 0 ) + return( ret ); + + buf += grp_len; + blen -= grp_len; + + if( ( ret = mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, point_format, + &pt_len, buf, blen ) ) != 0 ) + return( ret ); + + *olen = grp_len + pt_len; + return( 0 ); +} + +/* + * Setup and write the ServerKeyExchange parameters (RFC 4492) + * struct { + * ECParameters curve_params; + * ECPoint public; + * } ServerECDHParams; + */ +int mbedtls_ecdh_make_params( 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; +#else + (void) restart_enabled; +#endif + +#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT) + return( ecdh_make_params_internal( ctx, olen, ctx->point_format, buf, blen, + f_rng, p_rng, restart_enabled ) ); +#else + switch( ctx->var ) + { +#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED) + case MBEDTLS_ECDH_VARIANT_EVEREST: + return( mbedtls_everest_make_params( &ctx->ctx.everest_ecdh, olen, + buf, blen, f_rng, p_rng ) ); +#endif + case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0: + return( ecdh_make_params_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_params_internal( mbedtls_ecdh_context_mbed *ctx, + const unsigned char **buf, + const unsigned char *end ) +{ + return( mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, buf, + end - *buf ) ); +} + +/* + * Read the ServerKeyExhange parameters (RFC 4492) + * struct { + * ECParameters curve_params; + * ECPoint public; + * } ServerECDHParams; + */ +int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx, + const unsigned char **buf, + const unsigned char *end ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + mbedtls_ecp_group_id grp_id; + ECDH_VALIDATE_RET( ctx != NULL ); + ECDH_VALIDATE_RET( buf != NULL ); + ECDH_VALIDATE_RET( *buf != NULL ); + ECDH_VALIDATE_RET( end != NULL ); + + if( ( ret = mbedtls_ecp_tls_read_group_id( &grp_id, buf, end - *buf ) ) + != 0 ) + return( ret ); + + if( ( ret = mbedtls_ecdh_setup( ctx, grp_id ) ) != 0 ) + return( ret ); + +#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT) + return( ecdh_read_params_internal( ctx, buf, end ) ); +#else + switch( ctx->var ) + { +#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED) + case MBEDTLS_ECDH_VARIANT_EVEREST: + return( mbedtls_everest_read_params( &ctx->ctx.everest_ecdh, + buf, end) ); +#endif + case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0: + return( ecdh_read_params_internal( &ctx->ctx.mbed_ecdh, + buf, end ) ); + default: + return MBEDTLS_ERR_ECP_BAD_INPUT_DATA; + } +#endif +} + +static int ecdh_get_params_internal( mbedtls_ecdh_context_mbed *ctx, + const mbedtls_ecp_keypair *key, + mbedtls_ecdh_side side ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + + /* If it's not our key, just import the public part as Qp */ + if( side == MBEDTLS_ECDH_THEIRS ) + return( mbedtls_ecp_copy( &ctx->Qp, &key->Q ) ); + + /* Our key: import public (as Q) and private parts */ + if( side != MBEDTLS_ECDH_OURS ) + return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); + + if( ( ret = mbedtls_ecp_copy( &ctx->Q, &key->Q ) ) != 0 || + ( ret = mbedtls_mpi_copy( &ctx->d, &key->d ) ) != 0 ) + return( ret ); + + return( 0 ); +} + +/* + * Get parameters from a keypair + */ +int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx, + const mbedtls_ecp_keypair *key, + mbedtls_ecdh_side side ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + ECDH_VALIDATE_RET( ctx != NULL ); + ECDH_VALIDATE_RET( key != NULL ); + ECDH_VALIDATE_RET( side == MBEDTLS_ECDH_OURS || + side == MBEDTLS_ECDH_THEIRS ); + + if( mbedtls_ecdh_grp_id( ctx ) == MBEDTLS_ECP_DP_NONE ) + { + /* This is the first call to get_params(). Set up the context + * for use with the group. */ + if( ( ret = mbedtls_ecdh_setup( ctx, key->grp.id ) ) != 0 ) + return( ret ); + } + else + { + /* This is not the first call to get_params(). Check that the + * current key's group is the same as the context's, which was set + * from the first key's group. */ + if( mbedtls_ecdh_grp_id( ctx ) != key->grp.id ) + return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); + } + +#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT) + return( ecdh_get_params_internal( ctx, key, side ) ); +#else + switch( ctx->var ) + { +#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED) + case MBEDTLS_ECDH_VARIANT_EVEREST: + { + mbedtls_everest_ecdh_side s = side == MBEDTLS_ECDH_OURS ? + MBEDTLS_EVEREST_ECDH_OURS : + MBEDTLS_EVEREST_ECDH_THEIRS; + return( mbedtls_everest_get_params( &ctx->ctx.everest_ecdh, + key, s) ); + } +#endif + case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0: + return( ecdh_get_params_internal( &ctx->ctx.mbed_ecdh, + key, side ) ); + default: + return MBEDTLS_ERR_ECP_BAD_INPUT_DATA; + } +#endif +} + +static int ecdh_make_public_internal( mbedtls_ecdh_context_mbed *ctx, + size_t *olen, int point_format, + unsigned char *buf, size_t blen, + int (*f_rng)(void *, + unsigned char *, + size_t), + void *p_rng, + int restart_enabled ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; +#if defined(MBEDTLS_ECP_RESTARTABLE) + mbedtls_ecp_restart_ctx *rs_ctx = NULL; +#endif + + if( 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_gen_public_restartable( &ctx->grp, &ctx->d, &ctx->Q, + 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 ) + { +#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED) + case MBEDTLS_ECDH_VARIANT_EVEREST: + return( mbedtls_everest_make_public( &ctx->ctx.everest_ecdh, olen, + buf, blen, f_rng, p_rng ) ); +#endif + 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 = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + 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 ) + { +#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED) + case MBEDTLS_ECDH_VARIANT_EVEREST: + return( mbedtls_everest_read_public( &ctx->ctx.everest_ecdh, + buf, blen ) ); +#endif + 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 = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; +#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 ); + + if( mbedtls_ecp_get_type( &ctx->grp ) == MBEDTLS_ECP_TYPE_MONTGOMERY ) + return mbedtls_mpi_write_binary_le( &ctx->z, buf, *olen ); + + 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 ) + { +#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED) + case MBEDTLS_ECDH_VARIANT_EVEREST: + return( mbedtls_everest_calc_secret( &ctx->ctx.everest_ecdh, olen, + buf, blen, f_rng, p_rng ) ); +#endif + 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 */ |