/src/mbedtls/library/ecdh.c

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/*
 *  Elliptic curve Diffie-Hellman
 *
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 */

/*
 * References:
 *
 * SEC1 https://www.secg.org/sec1-v2.pdf
 * 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
}

mbedtls_ecp_group_id mbedtls_ecdh_get_grp_id(mbedtls_ecdh_context *ctx)
{
#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
    return ctx->MBEDTLS_PRIVATE(grp).id;
#else
    return ctx->MBEDTLS_PRIVATE(grp_id);
#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,
                                      (size_t) (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, (size_t) (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: 2024-11-21 07:03

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 OR GPL-2.0-or-later
6		*/
7
8		/*
9		* References:
10		*
11		* SEC1 https://www.secg.org/sec1-v2.pdf
12		* RFC 4492
13		*/
14
15		#include "common.h"
16
17		#if defined(MBEDTLS_ECDH_C)
18
19		#include "mbedtls/ecdh.h"
20		#include "mbedtls/platform_util.h"
21		#include "mbedtls/error.h"
22
23		#include <string.h>
24
25		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
26		typedef mbedtls_ecdh_context mbedtls_ecdh_context_mbed;
27		#endif
28
29		static mbedtls_ecp_group_id mbedtls_ecdh_grp_id(
30		const mbedtls_ecdh_context *ctx)
31	0	{
32		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
33		return ctx->grp.id;
34		#else
35	0	return ctx->grp_id;
36	0	#endif
37	0	}
38
39		int mbedtls_ecdh_can_do(mbedtls_ecp_group_id gid)
40	0	{
41		/* At this time, all groups support ECDH. */
42	0	(void) gid;
43	0	return 1;
44	0	}
45
46		#if !defined(MBEDTLS_ECDH_GEN_PUBLIC_ALT)
47		/*
48		* Generate public key (restartable version)
49		*
50		* Note: this internal function relies on its caller preserving the value of
51		* the output parameter 'd' across continuation calls. This would not be
52		* acceptable for a public function but is OK here as we control call sites.
53		*/
54		static int ecdh_gen_public_restartable(mbedtls_ecp_group *grp,
55		mbedtls_mpi d, mbedtls_ecp_point Q,
56		int (f_rng)(void , unsigned char *, size_t),
57		void *p_rng,
58		mbedtls_ecp_restart_ctx *rs_ctx)
59	0	{
60	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
61
62	0	int restarting = 0;
63		#if defined(MBEDTLS_ECP_RESTARTABLE)
64		restarting = (rs_ctx != NULL && rs_ctx->rsm != NULL);
65		#endif
66		/* If multiplication is in progress, we already generated a privkey */
67	0	if (!restarting) {
68	0	MBEDTLS_MPI_CHK(mbedtls_ecp_gen_privkey(grp, d, f_rng, p_rng));
69	0	}
70
71	0	MBEDTLS_MPI_CHK(mbedtls_ecp_mul_restartable(grp, Q, d, &grp->G,
72	0	f_rng, p_rng, rs_ctx));
73
74	0	cleanup:
75	0	return ret;
76	0	}
77
78		/*
79		* Generate public key
80		*/
81		int mbedtls_ecdh_gen_public(mbedtls_ecp_group grp, mbedtls_mpi d, mbedtls_ecp_point *Q,
82		int (f_rng)(void , unsigned char *, size_t),
83		void *p_rng)
84	0	{
85	0	return ecdh_gen_public_restartable(grp, d, Q, f_rng, p_rng, NULL);
86	0	}
87		#endif /* !MBEDTLS_ECDH_GEN_PUBLIC_ALT */
88
89		#if !defined(MBEDTLS_ECDH_COMPUTE_SHARED_ALT)
90		/*
91		* Compute shared secret (SEC1 3.3.1)
92		*/
93		static int ecdh_compute_shared_restartable(mbedtls_ecp_group *grp,
94		mbedtls_mpi *z,
95		const mbedtls_ecp_point Q, const mbedtls_mpi d,
96		int (f_rng)(void , unsigned char *, size_t),
97		void *p_rng,
98		mbedtls_ecp_restart_ctx *rs_ctx)
99	0	{
100	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
101	0	mbedtls_ecp_point P;
102
103	0	mbedtls_ecp_point_init(&P);
104
105	0	MBEDTLS_MPI_CHK(mbedtls_ecp_mul_restartable(grp, &P, d, Q,
106	0	f_rng, p_rng, rs_ctx));
107
108	0	if (mbedtls_ecp_is_zero(&P)) {
109	0	ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
110	0	goto cleanup;
111	0	}
112
113	0	MBEDTLS_MPI_CHK(mbedtls_mpi_copy(z, &P.X));
114
115	0	cleanup:
116	0	mbedtls_ecp_point_free(&P);
117
118	0	return ret;
119	0	}
120
121		/*
122		* Compute shared secret (SEC1 3.3.1)
123		*/
124		int mbedtls_ecdh_compute_shared(mbedtls_ecp_group grp, mbedtls_mpi z,
125		const mbedtls_ecp_point Q, const mbedtls_mpi d,
126		int (f_rng)(void , unsigned char *, size_t),
127		void *p_rng)
128	0	{
129	0	return ecdh_compute_shared_restartable(grp, z, Q, d,
130	0	f_rng, p_rng, NULL);
131	0	}
132		#endif /* !MBEDTLS_ECDH_COMPUTE_SHARED_ALT */
133
134		static void ecdh_init_internal(mbedtls_ecdh_context_mbed *ctx)
135	0	{
136	0	mbedtls_ecp_group_init(&ctx->grp);
137	0	mbedtls_mpi_init(&ctx->d);
138	0	mbedtls_ecp_point_init(&ctx->Q);
139	0	mbedtls_ecp_point_init(&ctx->Qp);
140	0	mbedtls_mpi_init(&ctx->z);
141
142		#if defined(MBEDTLS_ECP_RESTARTABLE)
143		mbedtls_ecp_restart_init(&ctx->rs);
144		#endif
145	0	}
146
147		mbedtls_ecp_group_id mbedtls_ecdh_get_grp_id(mbedtls_ecdh_context *ctx)
148	0	{
149		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
150		return ctx->MBEDTLS_PRIVATE(grp).id;
151		#else
152	0	return ctx->MBEDTLS_PRIVATE(grp_id);
153	0	#endif
154	0	}
155
156		/*
157		* Initialize context
158		*/
159		void mbedtls_ecdh_init(mbedtls_ecdh_context *ctx)
160	0	{
161		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
162		ecdh_init_internal(ctx);
163		mbedtls_ecp_point_init(&ctx->Vi);
164		mbedtls_ecp_point_init(&ctx->Vf);
165		mbedtls_mpi_init(&ctx->_d);
166		#else
167	0	memset(ctx, 0, sizeof(mbedtls_ecdh_context));
168
169	0	ctx->var = MBEDTLS_ECDH_VARIANT_NONE;
170	0	#endif
171	0	ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
172		#if defined(MBEDTLS_ECP_RESTARTABLE)
173		ctx->restart_enabled = 0;
174		#endif
175	0	}
176
177		static int ecdh_setup_internal(mbedtls_ecdh_context_mbed *ctx,
178		mbedtls_ecp_group_id grp_id)
179	0	{
180	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
181
182	0	ret = mbedtls_ecp_group_load(&ctx->grp, grp_id);
183	0	if (ret != 0) {
184	0	return MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE;
185	0	}
186
187	0	return 0;
188	0	}
189
190		/*
191		* Setup context
192		*/
193		int mbedtls_ecdh_setup(mbedtls_ecdh_context *ctx, mbedtls_ecp_group_id grp_id)
194	0	{
195		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
196		return ecdh_setup_internal(ctx, grp_id);
197		#else
198	0	switch (grp_id) {
199		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
200		case MBEDTLS_ECP_DP_CURVE25519:
201		ctx->point_format = MBEDTLS_ECP_PF_COMPRESSED;
202		ctx->var = MBEDTLS_ECDH_VARIANT_EVEREST;
203		ctx->grp_id = grp_id;
204		return mbedtls_everest_setup(&ctx->ctx.everest_ecdh, grp_id);
205		#endif
206	0	default:
207	0	ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
208	0	ctx->var = MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0;
209	0	ctx->grp_id = grp_id;
210	0	ecdh_init_internal(&ctx->ctx.mbed_ecdh);
211	0	return ecdh_setup_internal(&ctx->ctx.mbed_ecdh, grp_id);
212	0	}
213	0	#endif
214	0	}
215
216		static void ecdh_free_internal(mbedtls_ecdh_context_mbed *ctx)
217	0	{
218	0	mbedtls_ecp_group_free(&ctx->grp);
219	0	mbedtls_mpi_free(&ctx->d);
220	0	mbedtls_ecp_point_free(&ctx->Q);
221	0	mbedtls_ecp_point_free(&ctx->Qp);
222	0	mbedtls_mpi_free(&ctx->z);
223
224		#if defined(MBEDTLS_ECP_RESTARTABLE)
225		mbedtls_ecp_restart_free(&ctx->rs);
226		#endif
227	0	}
228
229		#if defined(MBEDTLS_ECP_RESTARTABLE)
230		/*
231		* Enable restartable operations for context
232		*/
233		void mbedtls_ecdh_enable_restart(mbedtls_ecdh_context *ctx)
234		{
235		ctx->restart_enabled = 1;
236		}
237		#endif
238
239		/*
240		* Free context
241		*/
242		void mbedtls_ecdh_free(mbedtls_ecdh_context *ctx)
243	0	{
244	0	if (ctx == NULL) {
245	0	return;
246	0	}
247
248		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
249		mbedtls_ecp_point_free(&ctx->Vi);
250		mbedtls_ecp_point_free(&ctx->Vf);
251		mbedtls_mpi_free(&ctx->_d);
252		ecdh_free_internal(ctx);
253		#else
254	0	switch (ctx->var) {
255		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
256		case MBEDTLS_ECDH_VARIANT_EVEREST:
257		mbedtls_everest_free(&ctx->ctx.everest_ecdh);
258		break;
259		#endif
260	0	case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
261	0	ecdh_free_internal(&ctx->ctx.mbed_ecdh);
262	0	break;
263	0	default:
264	0	break;
265	0	}
266
267	0	ctx->point_format = MBEDTLS_ECP_PF_UNCOMPRESSED;
268	0	ctx->var = MBEDTLS_ECDH_VARIANT_NONE;
269	0	ctx->grp_id = MBEDTLS_ECP_DP_NONE;
270	0	#endif
271	0	}
272
273		static int ecdh_make_params_internal(mbedtls_ecdh_context_mbed *ctx,
274		size_t *olen, int point_format,
275		unsigned char *buf, size_t blen,
276		int (f_rng)(void ,
277		unsigned char *,
278		size_t),
279		void *p_rng,
280		int restart_enabled)
281	0	{
282	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
283	0	size_t grp_len, pt_len;
284		#if defined(MBEDTLS_ECP_RESTARTABLE)
285		mbedtls_ecp_restart_ctx *rs_ctx = NULL;
286		#endif
287
288	0	if (ctx->grp.pbits == 0) {
289	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
290	0	}
291
292		#if defined(MBEDTLS_ECP_RESTARTABLE)
293		if (restart_enabled) {
294		rs_ctx = &ctx->rs;
295		}
296		#else
297	0	(void) restart_enabled;
298	0	#endif
299
300
301		#if defined(MBEDTLS_ECP_RESTARTABLE)
302		if ((ret = ecdh_gen_public_restartable(&ctx->grp, &ctx->d, &ctx->Q,
303		f_rng, p_rng, rs_ctx)) != 0) {
304		return ret;
305		}
306		#else
307	0	if ((ret = mbedtls_ecdh_gen_public(&ctx->grp, &ctx->d, &ctx->Q,
308	0	f_rng, p_rng)) != 0) {
309	0	return ret;
310	0	}
311	0	#endif /* MBEDTLS_ECP_RESTARTABLE */
312
313	0	if ((ret = mbedtls_ecp_tls_write_group(&ctx->grp, &grp_len, buf,
314	0	blen)) != 0) {
315	0	return ret;
316	0	}
317
318	0	buf += grp_len;
319	0	blen -= grp_len;
320
321	0	if ((ret = mbedtls_ecp_tls_write_point(&ctx->grp, &ctx->Q, point_format,
322	0	&pt_len, buf, blen)) != 0) {
323	0	return ret;
324	0	}
325
326	0	*olen = grp_len + pt_len;
327	0	return 0;
328	0	}
329
330		/*
331		* Setup and write the ServerKeyExchange parameters (RFC 4492)
332		* struct {
333		* ECParameters curve_params;
334		* ECPoint public;
335		* } ServerECDHParams;
336		*/
337		int mbedtls_ecdh_make_params(mbedtls_ecdh_context ctx, size_t olen,
338		unsigned char *buf, size_t blen,
339		int (f_rng)(void , unsigned char *, size_t),
340		void *p_rng)
341	0	{
342	0	int restart_enabled = 0;
343		#if defined(MBEDTLS_ECP_RESTARTABLE)
344		restart_enabled = ctx->restart_enabled;
345		#else
346	0	(void) restart_enabled;
347	0	#endif
348
349		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
350		return ecdh_make_params_internal(ctx, olen, ctx->point_format, buf, blen,
351		f_rng, p_rng, restart_enabled);
352		#else
353	0	switch (ctx->var) {
354		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
355		case MBEDTLS_ECDH_VARIANT_EVEREST:
356		return mbedtls_everest_make_params(&ctx->ctx.everest_ecdh, olen,
357		buf, blen, f_rng, p_rng);
358		#endif
359	0	case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
360	0	return ecdh_make_params_internal(&ctx->ctx.mbed_ecdh, olen,
361	0	ctx->point_format, buf, blen,
362	0	f_rng, p_rng,
363	0	restart_enabled);
364	0	default:
365	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
366	0	}
367	0	#endif
368	0	}
369
370		static int ecdh_read_params_internal(mbedtls_ecdh_context_mbed *ctx,
371		const unsigned char **buf,
372		const unsigned char *end)
373	0	{
374	0	return mbedtls_ecp_tls_read_point(&ctx->grp, &ctx->Qp, buf,
375	0	(size_t) (end - *buf));
376	0	}
377
378		/*
379		* Read the ServerKeyExchange parameters (RFC 4492)
380		* struct {
381		* ECParameters curve_params;
382		* ECPoint public;
383		* } ServerECDHParams;
384		*/
385		int mbedtls_ecdh_read_params(mbedtls_ecdh_context *ctx,
386		const unsigned char **buf,
387		const unsigned char *end)
388	0	{
389	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
390	0	mbedtls_ecp_group_id grp_id;
391	0	if ((ret = mbedtls_ecp_tls_read_group_id(&grp_id, buf, (size_t) (end - *buf)))
392	0	!= 0) {
393	0	return ret;
394	0	}
395
396	0	if ((ret = mbedtls_ecdh_setup(ctx, grp_id)) != 0) {
397	0	return ret;
398	0	}
399
400		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
401		return ecdh_read_params_internal(ctx, buf, end);
402		#else
403	0	switch (ctx->var) {
404		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
405		case MBEDTLS_ECDH_VARIANT_EVEREST:
406		return mbedtls_everest_read_params(&ctx->ctx.everest_ecdh,
407		buf, end);
408		#endif
409	0	case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
410	0	return ecdh_read_params_internal(&ctx->ctx.mbed_ecdh,
411	0	buf, end);
412	0	default:
413	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
414	0	}
415	0	#endif
416	0	}
417
418		static int ecdh_get_params_internal(mbedtls_ecdh_context_mbed *ctx,
419		const mbedtls_ecp_keypair *key,
420		mbedtls_ecdh_side side)
421	0	{
422	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
423
424		/* If it's not our key, just import the public part as Qp */
425	0	if (side == MBEDTLS_ECDH_THEIRS) {
426	0	return mbedtls_ecp_copy(&ctx->Qp, &key->Q);
427	0	}
428
429		/* Our key: import public (as Q) and private parts */
430	0	if (side != MBEDTLS_ECDH_OURS) {
431	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
432	0	}
433
434	0	if ((ret = mbedtls_ecp_copy(&ctx->Q, &key->Q)) != 0 \|\|
435	0	(ret = mbedtls_mpi_copy(&ctx->d, &key->d)) != 0) {
436	0	return ret;
437	0	}
438
439	0	return 0;
440	0	}
441
442		/*
443		* Get parameters from a keypair
444		*/
445		int mbedtls_ecdh_get_params(mbedtls_ecdh_context *ctx,
446		const mbedtls_ecp_keypair *key,
447		mbedtls_ecdh_side side)
448	0	{
449	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
450	0	if (side != MBEDTLS_ECDH_OURS && side != MBEDTLS_ECDH_THEIRS) {
451	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
452	0	}
453
454	0	if (mbedtls_ecdh_grp_id(ctx) == MBEDTLS_ECP_DP_NONE) {
455		/* This is the first call to get_params(). Set up the context
456		* for use with the group. */
457	0	if ((ret = mbedtls_ecdh_setup(ctx, key->grp.id)) != 0) {
458	0	return ret;
459	0	}
460	0	} else {
461		/* This is not the first call to get_params(). Check that the
462		* current key's group is the same as the context's, which was set
463		* from the first key's group. */
464	0	if (mbedtls_ecdh_grp_id(ctx) != key->grp.id) {
465	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
466	0	}
467	0	}
468
469		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
470		return ecdh_get_params_internal(ctx, key, side);
471		#else
472	0	switch (ctx->var) {
473		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
474		case MBEDTLS_ECDH_VARIANT_EVEREST:
475		{
476		mbedtls_everest_ecdh_side s = side == MBEDTLS_ECDH_OURS ?
477		MBEDTLS_EVEREST_ECDH_OURS :
478		MBEDTLS_EVEREST_ECDH_THEIRS;
479		return mbedtls_everest_get_params(&ctx->ctx.everest_ecdh,
480		key, s);
481		}
482		#endif
483	0	case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
484	0	return ecdh_get_params_internal(&ctx->ctx.mbed_ecdh,
485	0	key, side);
486	0	default:
487	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
488	0	}
489	0	#endif
490	0	}
491
492		static int ecdh_make_public_internal(mbedtls_ecdh_context_mbed *ctx,
493		size_t *olen, int point_format,
494		unsigned char *buf, size_t blen,
495		int (f_rng)(void ,
496		unsigned char *,
497		size_t),
498		void *p_rng,
499		int restart_enabled)
500	0	{
501	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
502		#if defined(MBEDTLS_ECP_RESTARTABLE)
503		mbedtls_ecp_restart_ctx *rs_ctx = NULL;
504		#endif
505
506	0	if (ctx->grp.pbits == 0) {
507	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
508	0	}
509
510		#if defined(MBEDTLS_ECP_RESTARTABLE)
511		if (restart_enabled) {
512		rs_ctx = &ctx->rs;
513		}
514		#else
515	0	(void) restart_enabled;
516	0	#endif
517
518		#if defined(MBEDTLS_ECP_RESTARTABLE)
519		if ((ret = ecdh_gen_public_restartable(&ctx->grp, &ctx->d, &ctx->Q,
520		f_rng, p_rng, rs_ctx)) != 0) {
521		return ret;
522		}
523		#else
524	0	if ((ret = mbedtls_ecdh_gen_public(&ctx->grp, &ctx->d, &ctx->Q,
525	0	f_rng, p_rng)) != 0) {
526	0	return ret;
527	0	}
528	0	#endif /* MBEDTLS_ECP_RESTARTABLE */
529
530	0	return mbedtls_ecp_tls_write_point(&ctx->grp, &ctx->Q, point_format, olen,
531	0	buf, blen);
532	0	}
533
534		/*
535		* Setup and export the client public value
536		*/
537		int mbedtls_ecdh_make_public(mbedtls_ecdh_context ctx, size_t olen,
538		unsigned char *buf, size_t blen,
539		int (f_rng)(void , unsigned char *, size_t),
540		void *p_rng)
541	0	{
542	0	int restart_enabled = 0;
543		#if defined(MBEDTLS_ECP_RESTARTABLE)
544		restart_enabled = ctx->restart_enabled;
545		#endif
546
547		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
548		return ecdh_make_public_internal(ctx, olen, ctx->point_format, buf, blen,
549		f_rng, p_rng, restart_enabled);
550		#else
551	0	switch (ctx->var) {
552		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
553		case MBEDTLS_ECDH_VARIANT_EVEREST:
554		return mbedtls_everest_make_public(&ctx->ctx.everest_ecdh, olen,
555		buf, blen, f_rng, p_rng);
556		#endif
557	0	case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
558	0	return ecdh_make_public_internal(&ctx->ctx.mbed_ecdh, olen,
559	0	ctx->point_format, buf, blen,
560	0	f_rng, p_rng,
561	0	restart_enabled);
562	0	default:
563	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
564	0	}
565	0	#endif
566	0	}
567
568		static int ecdh_read_public_internal(mbedtls_ecdh_context_mbed *ctx,
569		const unsigned char *buf, size_t blen)
570	0	{
571	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
572	0	const unsigned char *p = buf;
573
574	0	if ((ret = mbedtls_ecp_tls_read_point(&ctx->grp, &ctx->Qp, &p,
575	0	blen)) != 0) {
576	0	return ret;
577	0	}
578
579	0	if ((size_t) (p - buf) != blen) {
580	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
581	0	}
582
583	0	return 0;
584	0	}
585
586		/*
587		* Parse and import the client's public value
588		*/
589		int mbedtls_ecdh_read_public(mbedtls_ecdh_context *ctx,
590		const unsigned char *buf, size_t blen)
591	0	{
592		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
593		return ecdh_read_public_internal(ctx, buf, blen);
594		#else
595	0	switch (ctx->var) {
596		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
597		case MBEDTLS_ECDH_VARIANT_EVEREST:
598		return mbedtls_everest_read_public(&ctx->ctx.everest_ecdh,
599		buf, blen);
600		#endif
601	0	case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
602	0	return ecdh_read_public_internal(&ctx->ctx.mbed_ecdh,
603	0	buf, blen);
604	0	default:
605	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
606	0	}
607	0	#endif
608	0	}
609
610		static int ecdh_calc_secret_internal(mbedtls_ecdh_context_mbed *ctx,
611		size_t olen, unsigned char buf,
612		size_t blen,
613		int (f_rng)(void ,
614		unsigned char *,
615		size_t),
616		void *p_rng,
617		int restart_enabled)
618	0	{
619	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
620		#if defined(MBEDTLS_ECP_RESTARTABLE)
621		mbedtls_ecp_restart_ctx *rs_ctx = NULL;
622		#endif
623
624	0	if (ctx == NULL \|\| ctx->grp.pbits == 0) {
625	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
626	0	}
627
628		#if defined(MBEDTLS_ECP_RESTARTABLE)
629		if (restart_enabled) {
630		rs_ctx = &ctx->rs;
631		}
632		#else
633	0	(void) restart_enabled;
634	0	#endif
635
636		#if defined(MBEDTLS_ECP_RESTARTABLE)
637		if ((ret = ecdh_compute_shared_restartable(&ctx->grp, &ctx->z, &ctx->Qp,
638		&ctx->d, f_rng, p_rng,
639		rs_ctx)) != 0) {
640		return ret;
641		}
642		#else
643	0	if ((ret = mbedtls_ecdh_compute_shared(&ctx->grp, &ctx->z, &ctx->Qp,
644	0	&ctx->d, f_rng, p_rng)) != 0) {
645	0	return ret;
646	0	}
647	0	#endif /* MBEDTLS_ECP_RESTARTABLE */
648
649	0	if (mbedtls_mpi_size(&ctx->z) > blen) {
650	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
651	0	}
652
653	0	*olen = ctx->grp.pbits / 8 + ((ctx->grp.pbits % 8) != 0);
654
655	0	if (mbedtls_ecp_get_type(&ctx->grp) == MBEDTLS_ECP_TYPE_MONTGOMERY) {
656	0	return mbedtls_mpi_write_binary_le(&ctx->z, buf, *olen);
657	0	}
658
659	0	return mbedtls_mpi_write_binary(&ctx->z, buf, *olen);
660	0	}
661
662		/*
663		* Derive and export the shared secret
664		*/
665		int mbedtls_ecdh_calc_secret(mbedtls_ecdh_context ctx, size_t olen,
666		unsigned char *buf, size_t blen,
667		int (f_rng)(void , unsigned char *, size_t),
668		void *p_rng)
669	0	{
670	0	int restart_enabled = 0;
671		#if defined(MBEDTLS_ECP_RESTARTABLE)
672		restart_enabled = ctx->restart_enabled;
673		#endif
674
675		#if defined(MBEDTLS_ECDH_LEGACY_CONTEXT)
676		return ecdh_calc_secret_internal(ctx, olen, buf, blen, f_rng, p_rng,
677		restart_enabled);
678		#else
679	0	switch (ctx->var) {
680		#if defined(MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED)
681		case MBEDTLS_ECDH_VARIANT_EVEREST:
682		return mbedtls_everest_calc_secret(&ctx->ctx.everest_ecdh, olen,
683		buf, blen, f_rng, p_rng);
684		#endif
685	0	case MBEDTLS_ECDH_VARIANT_MBEDTLS_2_0:
686	0	return ecdh_calc_secret_internal(&ctx->ctx.mbed_ecdh, olen, buf,
687	0	blen, f_rng, p_rng,
688	0	restart_enabled);
689	0	default:
690	0	return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
691	0	}
692	0	#endif
693	0	}
694		#endif /* MBEDTLS_ECDH_C */