729 lines
22 KiB
C
729 lines
22 KiB
C
/*
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* Elliptic curve Diffie-Hellman
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
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*/
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/*
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* References:
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*
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* SEC1 https://www.secg.org/sec1-v2.pdf
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* RFC 4492
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*/
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#include "common.h"
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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 "mbedtls/error.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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static mbedtls_ecp_group_id mbedtls_ecdh_grp_id(
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const mbedtls_ecdh_context *ctx)
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{
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#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
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return ctx->grp.id;
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#else
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return ctx->grp_id;
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#endif
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}
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int mbedtls_ecdh_can_do(mbedtls_ecp_group_id gid)
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{
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/* At this time, all groups support ECDH. */
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(void) gid;
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return 1;
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}
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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 = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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int restarting = 0;
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#if defined(MBEDTLS_ECP_RESTARTABLE)
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restarting = (rs_ctx != NULL && rs_ctx->rsm != NULL);
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#endif
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/* If multiplication is in progress, we already generated a privkey */
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if (!restarting) {
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MBEDTLS_MPI_CHK(mbedtls_ecp_gen_privkey(grp, d, f_rng, p_rng));
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}
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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 = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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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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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 = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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ret = mbedtls_ecp_group_load(&ctx->grp, grp_id);
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if (ret != 0) {
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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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#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
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case MBEDTLS_ECP_DP_CURVE25519:
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ctx->point_format = MBEDTLS_ECP_PF_COMPRESSED;
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ctx->var = MBEDTLS_ECDH_VARIANT_EVEREST;
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ctx->grp_id = grp_id;
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return mbedtls_everest_setup(&ctx->ctx.everest_ecdh, grp_id);
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#endif
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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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}
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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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#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
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case MBEDTLS_ECDH_VARIANT_EVEREST:
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mbedtls_everest_free(&ctx->ctx.everest_ecdh);
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break;
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#endif
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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 = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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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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}
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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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}
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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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}
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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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}
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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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}
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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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}
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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 ServerKeyExchange 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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#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
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case MBEDTLS_ECDH_VARIANT_EVEREST:
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return mbedtls_everest_make_params(&ctx->ctx.everest_ecdh, olen,
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buf, blen, f_rng, p_rng);
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#endif
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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 ServerKeyExchange 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 = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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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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}
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if ((ret = mbedtls_ecdh_setup(ctx, grp_id)) != 0) {
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return ret;
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}
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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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#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
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case MBEDTLS_ECDH_VARIANT_EVEREST:
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return mbedtls_everest_read_params(&ctx->ctx.everest_ecdh,
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buf, end);
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#endif
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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 = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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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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}
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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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}
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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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}
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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 = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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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 (mbedtls_ecdh_grp_id(ctx) == MBEDTLS_ECP_DP_NONE) {
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/* This is the first call to get_params(). Set up the context
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* for use with the group. */
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if ((ret = mbedtls_ecdh_setup(ctx, key->grp.id)) != 0) {
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return ret;
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}
|
|
} 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 */
|