/src/mbedtls/library/ecdh.c

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/*
 *  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>

#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;

    int restarting = 0;
#if defined(MBEDTLS_ECP_RESTARTABLE)
    restarting = (rs_ctx != NULL && rs_ctx->rsm != NULL);
#endif
    /* If multiplication is in progress, we already generated a privkey */
    if (!restarting) {
        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)
{
    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)
{
    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)
{
#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)
{
#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)
{
    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;
#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 ServerKeyExchange 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;
    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;
    if (side != MBEDTLS_ECDH_OURS && side != MBEDTLS_ECDH_THEIRS) {
        return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
    }

    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;
#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)
{
#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;
#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 */

Coverage Report

Created: 2023-09-24 16:03

Line	Count	Source (jump to first uncovered line)
1		/*
2		* Elliptic curve Diffie-Hellman
3		*
4		* Copyright The Mbed TLS Contributors
5		* SPDX-License-Identifier: Apache-2.0
6		*
7		* Licensed under the Apache License, Version 2.0 (the "License"); you may
8		* not use this file except in compliance with the License.
9		* You may obtain a copy of the License at
10		*
11		* http://www.apache.org/licenses/LICENSE-2.0
12		*
13		* Unless required by applicable law or agreed to in writing, software
14		* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
15		* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16		* See the License for the specific language governing permissions and
17		* limitations under the License.
18		*/
19
20		/*
21		* References:
22		*
23		* SEC1 http://www.secg.org/index.php?action=secg,docs_secg
24		* RFC 4492
25		*/
26
27		#include "common.h"
28
29		#if defined(MBEDTLS_ECDH_C)
30
31		#include "mbedtls/ecdh.h"
32		#include "mbedtls/platform_util.h"
33		#include "mbedtls/error.h"
34
35		#include <string.h>
36
37		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
38		typedef mbedtls_ecdh_context mbedtls_ecdh_context_mbed;
39		#endif
40
41		static mbedtls_ecp_group_id mbedtls_ecdh_grp_id(
42		const mbedtls_ecdh_context *ctx)
43	149	{
44		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
45		return ctx->grp.id;
46		#else
47	149	return ctx->grp_id;
48	149	#endif
49	149	}
50
51		int mbedtls_ecdh_can_do(mbedtls_ecp_group_id gid)
52	0	{
53		/* At this time, all groups support ECDH. */
54	0	(void) gid;
55	0	return 1;
56	0	}
57
58		#if !defined(MBEDTLS_ECDH_GEN_PUBLIC_ALT)
59		/*
60		* Generate public key (restartable version)
61		*
62		* Note: this internal function relies on its caller preserving the value of
63		* the output parameter 'd' across continuation calls. This would not be
64		* acceptable for a public function but is OK here as we control call sites.
65		*/
66		static int ecdh_gen_public_restartable(mbedtls_ecp_group *grp,
67		mbedtls_mpi d, mbedtls_ecp_point Q,
68		int (f_rng)(void , unsigned char *, size_t),
69		void *p_rng,
70		mbedtls_ecp_restart_ctx *rs_ctx)
71	0	{
72	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
73
74	0	int restarting = 0;
75		#if defined(MBEDTLS_ECP_RESTARTABLE)
76		restarting = (rs_ctx != NULL && rs_ctx->rsm != NULL);
77		#endif
78		/* If multiplication is in progress, we already generated a privkey */
79	0	if (!restarting) {
80	0	MBEDTLS_MPI_CHK(mbedtls_ecp_gen_privkey(grp, d, f_rng, p_rng));
81	0	}
82
83	0	MBEDTLS_MPI_CHK(mbedtls_ecp_mul_restartable(grp, Q, d, &grp->G,
84	0	f_rng, p_rng, rs_ctx));
85
86	0	cleanup:
87	0	return ret;
88	0	}
89
90		/*
91		* Generate public key
92		*/
93		int mbedtls_ecdh_gen_public(mbedtls_ecp_group grp, mbedtls_mpi d, mbedtls_ecp_point *Q,
94		int (f_rng)(void , unsigned char *, size_t),
95		void *p_rng)
96	0	{
97	0	return ecdh_gen_public_restartable(grp, d, Q, f_rng, p_rng, NULL);
98	0	}
99		#endif /* !MBEDTLS_ECDH_GEN_PUBLIC_ALT */
100
101		#if !defined(MBEDTLS_ECDH_COMPUTE_SHARED_ALT)
102		/*
103		* Compute shared secret (SEC1 3.3.1)
104		*/
105		static int ecdh_compute_shared_restartable(mbedtls_ecp_group *grp,
106		mbedtls_mpi *z,
107		const mbedtls_ecp_point Q, const mbedtls_mpi d,
108		int (f_rng)(void , unsigned char *, size_t),
109		void *p_rng,
110		mbedtls_ecp_restart_ctx *rs_ctx)
111	0	{
112	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
113	0	mbedtls_ecp_point P;
114
115	0	mbedtls_ecp_point_init(&P);
116
117	0	MBEDTLS_MPI_CHK(mbedtls_ecp_mul_restartable(grp, &P, d, Q,
118	0	f_rng, p_rng, rs_ctx));
119
120	0	if (mbedtls_ecp_is_zero(&P)) {
121	0	ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
122	0	goto cleanup;
123	0	}
124
125	0	MBEDTLS_MPI_CHK(mbedtls_mpi_copy(z, &P.X));
126
127	0	cleanup:
128	0	mbedtls_ecp_point_free(&P);
129
130	0	return ret;
131	0	}
132
133		/*
134		* Compute shared secret (SEC1 3.3.1)
135		*/
136		int mbedtls_ecdh_compute_shared(mbedtls_ecp_group grp, mbedtls_mpi z,
137		const mbedtls_ecp_point Q, const mbedtls_mpi d,
138		int (f_rng)(void , unsigned char *, size_t),
139		void *p_rng)
140	0	{
141	0	return ecdh_compute_shared_restartable(grp, z, Q, d,
142	0	f_rng, p_rng, NULL);
143	0	}
144		#endif /* !MBEDTLS_ECDH_COMPUTE_SHARED_ALT */
145
146		static void ecdh_init_internal(mbedtls_ecdh_context_mbed *ctx)
147	4.19k	{
148	4.19k	mbedtls_ecp_group_init(&ctx->grp);
149	4.19k	mbedtls_mpi_init(&ctx->d);
150	4.19k	mbedtls_ecp_point_init(&ctx->Q);
151	4.19k	mbedtls_ecp_point_init(&ctx->Qp);
152	4.19k	mbedtls_mpi_init(&ctx->z);
153
154		#if defined(MBEDTLS_ECP_RESTARTABLE)
155		mbedtls_ecp_restart_init(&ctx->rs);
156		#endif
157	4.19k	}
158
159		/*
160		* Initialize context
161		*/
162		void mbedtls_ecdh_init(mbedtls_ecdh_context *ctx)
163	28.3k	{
164		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
165		ecdh_init_internal(ctx);
166		mbedtls_ecp_point_init(&ctx->Vi);
167		mbedtls_ecp_point_init(&ctx->Vf);
168		mbedtls_mpi_init(&ctx->_d);
169		#else
170	28.3k	memset(ctx, 0, sizeof(mbedtls_ecdh_context));
171
172	28.3k	ctx->var = MBEDTLS_ECDH_VARIANT_NONE;
173	28.3k	#endif
174	28.3k	ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
175		#if defined(MBEDTLS_ECP_RESTARTABLE)
176		ctx->restart_enabled = 0;
177		#endif
178	28.3k	}
179
180		static int ecdh_setup_internal(mbedtls_ecdh_context_mbed *ctx,
181		mbedtls_ecp_group_id grp_id)
182	4.19k	{
183	4.19k	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
184
185	4.19k	ret = mbedtls_ecp_group_load(&ctx->grp, grp_id);
186	4.19k	if (ret != 0) {
187	0	return MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE;
188	0	}
189
190	4.19k	return 0;
191	4.19k	}
192
193		/*
194		* Setup context
195		*/
196		int mbedtls_ecdh_setup(mbedtls_ecdh_context *ctx, mbedtls_ecp_group_id grp_id)
197	4.19k	{
198		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
199		return ecdh_setup_internal(ctx, grp_id);
200		#else
201	4.19k	switch (grp_id) {
202		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
203		case MBEDTLS_ECP_DP_CURVE25519:
204		ctx->point_format = MBEDTLS_ECP_PF_COMPRESSED;
205		ctx->var = MBEDTLS_ECDH_VARIANT_EVEREST;
206		ctx->grp_id = grp_id;
207		return mbedtls_everest_setup(&ctx->ctx.everest_ecdh, grp_id);
208		#endif
209	4.19k	default:
210	4.19k	ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
211	4.19k	ctx->var = MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0;
212	4.19k	ctx->grp_id = grp_id;
213	4.19k	ecdh_init_internal(&ctx->ctx.mbed_ecdh);
214	4.19k	return ecdh_setup_internal(&ctx->ctx.mbed_ecdh, grp_id);
215	4.19k	}
216	4.19k	#endif
217	4.19k	}
218
219		static void ecdh_free_internal(mbedtls_ecdh_context_mbed *ctx)
220	4.19k	{
221	4.19k	mbedtls_ecp_group_free(&ctx->grp);
222	4.19k	mbedtls_mpi_free(&ctx->d);
223	4.19k	mbedtls_ecp_point_free(&ctx->Q);
224	4.19k	mbedtls_ecp_point_free(&ctx->Qp);
225	4.19k	mbedtls_mpi_free(&ctx->z);
226
227		#if defined(MBEDTLS_ECP_RESTARTABLE)
228		mbedtls_ecp_restart_free(&ctx->rs);
229		#endif
230	4.19k	}
231
232		#if defined(MBEDTLS_ECP_RESTARTABLE)
233		/*
234		* Enable restartable operations for context
235		*/
236		void mbedtls_ecdh_enable_restart(mbedtls_ecdh_context *ctx)
237		{
238		ctx->restart_enabled = 1;
239		}
240		#endif
241
242		/*
243		* Free context
244		*/
245		void mbedtls_ecdh_free(mbedtls_ecdh_context *ctx)
246	28.3k	{
247	28.3k	if (ctx == NULL) {
248	0	return;
249	0	}
250
251		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
252		mbedtls_ecp_point_free(&ctx->Vi);
253		mbedtls_ecp_point_free(&ctx->Vf);
254		mbedtls_mpi_free(&ctx->_d);
255		ecdh_free_internal(ctx);
256		#else
257	28.3k	switch (ctx->var) {
258		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
259		case MBEDTLS_ECDH_VARIANT_EVEREST:
260		mbedtls_everest_free(&ctx->ctx.everest_ecdh);
261		break;
262		#endif
263	4.19k	case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
264	4.19k	ecdh_free_internal(&ctx->ctx.mbed_ecdh);
265	4.19k	break;
266	24.1k	default:
267	24.1k	break;
268	28.3k	}
269
270	28.3k	ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
271	28.3k	ctx->var = MBEDTLS_ECDH_VARIANT_NONE;
272	28.3k	ctx->grp_id = MBEDTLS_ECP_DP_NONE;
273	28.3k	#endif
274	28.3k	}
275
276		static int ecdh_make_params_internal(mbedtls_ecdh_context_mbed *ctx,
277		size_t *olen, int point_format,
278		unsigned char *buf, size_t blen,
279		int (f_rng)(void ,
280		unsigned char *,
281		size_t),
282		void *p_rng,
283		int restart_enabled)
284	0	{
285	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
286	0	size_t grp_len, pt_len;
287		#if defined(MBEDTLS_ECP_RESTARTABLE)
288		mbedtls_ecp_restart_ctx *rs_ctx = NULL;
289		#endif
290
291	0	if (ctx->grp.pbits == 0) {
292	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
293	0	}
294
295		#if defined(MBEDTLS_ECP_RESTARTABLE)
296		if (restart_enabled) {
297		rs_ctx = &ctx->rs;
298		}
299		#else
300	0	(void) restart_enabled;
301	0	#endif
302
303
304		#if defined(MBEDTLS_ECP_RESTARTABLE)
305		if ((ret = ecdh_gen_public_restartable(&ctx->grp, &ctx->d, &ctx->Q,
306		f_rng, p_rng, rs_ctx)) != 0) {
307		return ret;
308		}
309		#else
310	0	if ((ret = mbedtls_ecdh_gen_public(&ctx->grp, &ctx->d, &ctx->Q,
311	0	f_rng, p_rng)) != 0) {
312	0	return ret;
313	0	}
314	0	#endif /* MBEDTLS_ECP_RESTARTABLE */
315
316	0	if ((ret = mbedtls_ecp_tls_write_group(&ctx->grp, &grp_len, buf,
317	0	blen)) != 0) {
318	0	return ret;
319	0	}
320
321	0	buf += grp_len;
322	0	blen -= grp_len;
323
324	0	if ((ret = mbedtls_ecp_tls_write_point(&ctx->grp, &ctx->Q, point_format,
325	0	&pt_len, buf, blen)) != 0) {
326	0	return ret;
327	0	}
328
329	0	*olen = grp_len + pt_len;
330	0	return 0;
331	0	}
332
333		/*
334		* Setup and write the ServerKeyExchange parameters (RFC 4492)
335		* struct {
336		* ECParameters curve_params;
337		* ECPoint public;
338		* } ServerECDHParams;
339		*/
340		int mbedtls_ecdh_make_params(mbedtls_ecdh_context ctx, size_t olen,
341		unsigned char *buf, size_t blen,
342		int (f_rng)(void , unsigned char *, size_t),
343		void *p_rng)
344	0	{
345	0	int restart_enabled = 0;
346		#if defined(MBEDTLS_ECP_RESTARTABLE)
347		restart_enabled = ctx->restart_enabled;
348		#else
349	0	(void) restart_enabled;
350	0	#endif
351
352		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
353		return ecdh_make_params_internal(ctx, olen, ctx->point_format, buf, blen,
354		f_rng, p_rng, restart_enabled);
355		#else
356	0	switch (ctx->var) {
357		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
358		case MBEDTLS_ECDH_VARIANT_EVEREST:
359		return mbedtls_everest_make_params(&ctx->ctx.everest_ecdh, olen,
360		buf, blen, f_rng, p_rng);
361		#endif
362	0	case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
363	0	return ecdh_make_params_internal(&ctx->ctx.mbed_ecdh, olen,
364	0	ctx->point_format, buf, blen,
365	0	f_rng, p_rng,
366	0	restart_enabled);
367	0	default:
368	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
369	0	}
370	0	#endif
371	0	}
372
373		static int ecdh_read_params_internal(mbedtls_ecdh_context_mbed *ctx,
374		const unsigned char **buf,
375		const unsigned char *end)
376	4.04k	{
377	4.04k	return mbedtls_ecp_tls_read_point(&ctx->grp, &ctx->Qp, buf,
378	4.04k	end - *buf);
379	4.04k	}
380
381		/*
382		* Read the ServerKeyExchange parameters (RFC 4492)
383		* struct {
384		* ECParameters curve_params;
385		* ECPoint public;
386		* } ServerECDHParams;
387		*/
388		int mbedtls_ecdh_read_params(mbedtls_ecdh_context *ctx,
389		const unsigned char **buf,
390		const unsigned char *end)
391	4.09k	{
392	4.09k	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
393	4.09k	mbedtls_ecp_group_id grp_id;
394	4.09k	if ((ret = mbedtls_ecp_tls_read_group_id(&grp_id, buf, end - *buf))
395	4.09k	!= 0) {
396	56	return ret;
397	56	}
398
399	4.04k	if ((ret = mbedtls_ecdh_setup(ctx, grp_id)) != 0) {
400	0	return ret;
401	0	}
402
403		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
404		return ecdh_read_params_internal(ctx, buf, end);
405		#else
406	4.04k	switch (ctx->var) {
407		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
408		case MBEDTLS_ECDH_VARIANT_EVEREST:
409		return mbedtls_everest_read_params(&ctx->ctx.everest_ecdh,
410		buf, end);
411		#endif
412	4.04k	case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
413	4.04k	return ecdh_read_params_internal(&ctx->ctx.mbed_ecdh,
414	4.04k	buf, end);
415	0	default:
416	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
417	4.04k	}
418	4.04k	#endif
419	4.04k	}
420
421		static int ecdh_get_params_internal(mbedtls_ecdh_context_mbed *ctx,
422		const mbedtls_ecp_keypair *key,
423		mbedtls_ecdh_side side)
424	149	{
425	149	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
426
427		/* If it's not our key, just import the public part as Qp */
428	149	if (side == MBEDTLS_ECDH_THEIRS) {
429	149	return mbedtls_ecp_copy(&ctx->Qp, &key->Q);
430	149	}
431
432		/* Our key: import public (as Q) and private parts */
433	0	if (side != MBEDTLS_ECDH_OURS) {
434	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
435	0	}
436
437	0	if ((ret = mbedtls_ecp_copy(&ctx->Q, &key->Q)) != 0 \|\|
438	0	(ret = mbedtls_mpi_copy(&ctx->d, &key->d)) != 0) {
439	0	return ret;
440	0	}
441
442	0	return 0;
443	0	}
444
445		/*
446		* Get parameters from a keypair
447		*/
448		int mbedtls_ecdh_get_params(mbedtls_ecdh_context *ctx,
449		const mbedtls_ecp_keypair *key,
450		mbedtls_ecdh_side side)
451	149	{
452	149	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
453	149	if (side != MBEDTLS_ECDH_OURS && side != MBEDTLS_ECDH_THEIRS) {
454	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
455	0	}
456
457	149	if (mbedtls_ecdh_grp_id(ctx) == MBEDTLS_ECP_DP_NONE) {
458		/* This is the first call to get_params(). Set up the context
459		* for use with the group. */
460	149	if ((ret = mbedtls_ecdh_setup(ctx, key->grp.id)) != 0) {
461	0	return ret;
462	0	}
463	149	} else {
464		/* This is not the first call to get_params(). Check that the
465		* current key's group is the same as the context's, which was set
466		* from the first key's group. */
467	0	if (mbedtls_ecdh_grp_id(ctx) != key->grp.id) {
468	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
469	0	}
470	0	}
471
472		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
473		return ecdh_get_params_internal(ctx, key, side);
474		#else
475	149	switch (ctx->var) {
476		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
477		case MBEDTLS_ECDH_VARIANT_EVEREST:
478		{
479		mbedtls_everest_ecdh_side s = side == MBEDTLS_ECDH_OURS ?
480		MBEDTLS_EVEREST_ECDH_OURS :
481		MBEDTLS_EVEREST_ECDH_THEIRS;
482		return mbedtls_everest_get_params(&ctx->ctx.everest_ecdh,
483		key, s);
484		}
485		#endif
486	149	case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
487	149	return ecdh_get_params_internal(&ctx->ctx.mbed_ecdh,
488	149	key, side);
489	0	default:
490	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
491	149	}
492	149	#endif
493	149	}
494
495		static int ecdh_make_public_internal(mbedtls_ecdh_context_mbed *ctx,
496		size_t *olen, int point_format,
497		unsigned char *buf, size_t blen,
498		int (f_rng)(void ,
499		unsigned char *,
500		size_t),
501		void *p_rng,
502		int restart_enabled)
503	0	{
504	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
505		#if defined(MBEDTLS_ECP_RESTARTABLE)
506		mbedtls_ecp_restart_ctx *rs_ctx = NULL;
507		#endif
508
509	0	if (ctx->grp.pbits == 0) {
510	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
511	0	}
512
513		#if defined(MBEDTLS_ECP_RESTARTABLE)
514		if (restart_enabled) {
515		rs_ctx = &ctx->rs;
516		}
517		#else
518	0	(void) restart_enabled;
519	0	#endif
520
521		#if defined(MBEDTLS_ECP_RESTARTABLE)
522		if ((ret = ecdh_gen_public_restartable(&ctx->grp, &ctx->d, &ctx->Q,
523		f_rng, p_rng, rs_ctx)) != 0) {
524		return ret;
525		}
526		#else
527	0	if ((ret = mbedtls_ecdh_gen_public(&ctx->grp, &ctx->d, &ctx->Q,
528	0	f_rng, p_rng)) != 0) {
529	0	return ret;
530	0	}
531	0	#endif /* MBEDTLS_ECP_RESTARTABLE */
532
533	0	return mbedtls_ecp_tls_write_point(&ctx->grp, &ctx->Q, point_format, olen,
534	0	buf, blen);
535	0	}
536
537		/*
538		* Setup and export the client public value
539		*/
540		int mbedtls_ecdh_make_public(mbedtls_ecdh_context ctx, size_t olen,
541		unsigned char *buf, size_t blen,
542		int (f_rng)(void , unsigned char *, size_t),
543		void *p_rng)
544	0	{
545	0	int restart_enabled = 0;
546		#if defined(MBEDTLS_ECP_RESTARTABLE)
547		restart_enabled = ctx->restart_enabled;
548		#endif
549
550		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
551		return ecdh_make_public_internal(ctx, olen, ctx->point_format, buf, blen,
552		f_rng, p_rng, restart_enabled);
553		#else
554	0	switch (ctx->var) {
555		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
556		case MBEDTLS_ECDH_VARIANT_EVEREST:
557		return mbedtls_everest_make_public(&ctx->ctx.everest_ecdh, olen,
558		buf, blen, f_rng, p_rng);
559		#endif
560	0	case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
561	0	return ecdh_make_public_internal(&ctx->ctx.mbed_ecdh, olen,
562	0	ctx->point_format, buf, blen,
563	0	f_rng, p_rng,
564	0	restart_enabled);
565	0	default:
566	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
567	0	}
568	0	#endif
569	0	}
570
571		static int ecdh_read_public_internal(mbedtls_ecdh_context_mbed *ctx,
572		const unsigned char *buf, size_t blen)
573	0	{
574	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
575	0	const unsigned char *p = buf;
576
577	0	if ((ret = mbedtls_ecp_tls_read_point(&ctx->grp, &ctx->Qp, &p,
578	0	blen)) != 0) {
579	0	return ret;
580	0	}
581
582	0	if ((size_t) (p - buf) != blen) {
583	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
584	0	}
585
586	0	return 0;
587	0	}
588
589		/*
590		* Parse and import the client's public value
591		*/
592		int mbedtls_ecdh_read_public(mbedtls_ecdh_context *ctx,
593		const unsigned char *buf, size_t blen)
594	0	{
595		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
596		return ecdh_read_public_internal(ctx, buf, blen);
597		#else
598	0	switch (ctx->var) {
599		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
600		case MBEDTLS_ECDH_VARIANT_EVEREST:
601		return mbedtls_everest_read_public(&ctx->ctx.everest_ecdh,
602		buf, blen);
603		#endif
604	0	case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
605	0	return ecdh_read_public_internal(&ctx->ctx.mbed_ecdh,
606	0	buf, blen);
607	0	default:
608	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
609	0	}
610	0	#endif
611	0	}
612
613		static int ecdh_calc_secret_internal(mbedtls_ecdh_context_mbed *ctx,
614		size_t olen, unsigned char buf,
615		size_t blen,
616		int (f_rng)(void ,
617		unsigned char *,
618		size_t),
619		void *p_rng,
620		int restart_enabled)
621	0	{
622	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
623		#if defined(MBEDTLS_ECP_RESTARTABLE)
624		mbedtls_ecp_restart_ctx *rs_ctx = NULL;
625		#endif
626
627	0	if (ctx == NULL \|\| ctx->grp.pbits == 0) {
628	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
629	0	}
630
631		#if defined(MBEDTLS_ECP_RESTARTABLE)
632		if (restart_enabled) {
633		rs_ctx = &ctx->rs;
634		}
635		#else
636	0	(void) restart_enabled;
637	0	#endif
638
639		#if defined(MBEDTLS_ECP_RESTARTABLE)
640		if ((ret = ecdh_compute_shared_restartable(&ctx->grp, &ctx->z, &ctx->Qp,
641		&ctx->d, f_rng, p_rng,
642		rs_ctx)) != 0) {
643		return ret;
644		}
645		#else
646	0	if ((ret = mbedtls_ecdh_compute_shared(&ctx->grp, &ctx->z, &ctx->Qp,
647	0	&ctx->d, f_rng, p_rng)) != 0) {
648	0	return ret;
649	0	}
650	0	#endif /* MBEDTLS_ECP_RESTARTABLE */
651
652	0	if (mbedtls_mpi_size(&ctx->z) > blen) {
653	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
654	0	}
655
656	0	*olen = ctx->grp.pbits / 8 + ((ctx->grp.pbits % 8) != 0);
657
658	0	if (mbedtls_ecp_get_type(&ctx->grp) == MBEDTLS_ECP_TYPE_MONTGOMERY) {
659	0	return mbedtls_mpi_write_binary_le(&ctx->z, buf, *olen);
660	0	}
661
662	0	return mbedtls_mpi_write_binary(&ctx->z, buf, *olen);
663	0	}
664
665		/*
666		* Derive and export the shared secret
667		*/
668		int mbedtls_ecdh_calc_secret(mbedtls_ecdh_context ctx, size_t olen,
669		unsigned char *buf, size_t blen,
670		int (f_rng)(void , unsigned char *, size_t),
671		void *p_rng)
672	0	{
673	0	int restart_enabled = 0;
674		#if defined(MBEDTLS_ECP_RESTARTABLE)
675		restart_enabled = ctx->restart_enabled;
676		#endif
677
678		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
679		return ecdh_calc_secret_internal(ctx, olen, buf, blen, f_rng, p_rng,
680		restart_enabled);
681		#else
682	0	switch (ctx->var) {
683		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
684		case MBEDTLS_ECDH_VARIANT_EVEREST:
685		return mbedtls_everest_calc_secret(&ctx->ctx.everest_ecdh, olen,
686		buf, blen, f_rng, p_rng);
687		#endif
688	0	case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
689	0	return ecdh_calc_secret_internal(&ctx->ctx.mbed_ecdh, olen, buf,
690	0	blen, f_rng, p_rng,
691	0	restart_enabled);
692	0	default:
693	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
694	0	}
695	0	#endif
696	0	}
697		#endif /* MBEDTLS_ECDH_C */