/src/openssl35/providers/implementations/exchange/ecdh_exch.c

Source
/*
 * Copyright 2020-2024 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

/*
 * ECDH low level APIs are deprecated for public use, but still ok for
 * internal use.
 */
#include "internal/deprecated.h"

#include <string.h>
#include <openssl/crypto.h>
#include <openssl/evp.h>
#include <openssl/core_dispatch.h>
#include <openssl/core_names.h>
#include <openssl/ec.h>
#include <openssl/params.h>
#include <openssl/err.h>
#include <openssl/proverr.h>
#include "prov/provider_ctx.h"
#include "prov/providercommon.h"
#include "prov/implementations.h"
#include "prov/securitycheck.h"
#include "crypto/ec.h" /* ossl_ecdh_kdf_X9_63() */

static OSSL_FUNC_keyexch_newctx_fn ecdh_newctx;
static OSSL_FUNC_keyexch_init_fn ecdh_init;
static OSSL_FUNC_keyexch_set_peer_fn ecdh_set_peer;
static OSSL_FUNC_keyexch_derive_fn ecdh_derive;
static OSSL_FUNC_keyexch_freectx_fn ecdh_freectx;
static OSSL_FUNC_keyexch_dupctx_fn ecdh_dupctx;
static OSSL_FUNC_keyexch_set_ctx_params_fn ecdh_set_ctx_params;
static OSSL_FUNC_keyexch_settable_ctx_params_fn ecdh_settable_ctx_params;
static OSSL_FUNC_keyexch_get_ctx_params_fn ecdh_get_ctx_params;
static OSSL_FUNC_keyexch_gettable_ctx_params_fn ecdh_gettable_ctx_params;

enum kdf_type {
    PROV_ECDH_KDF_NONE = 0,
    PROV_ECDH_KDF_X9_63
};

/*
 * What's passed as an actual key is defined by the KEYMGMT interface.
 * We happen to know that our KEYMGMT simply passes EC_KEY structures, so
 * we use that here too.
 */

typedef struct {
    OSSL_LIB_CTX *libctx;

    EC_KEY *k;
    EC_KEY *peerk;

    /*
     * ECDH cofactor mode:
     *
     *  . 0  disabled
     *  . 1  enabled
     *  . -1 use cofactor mode set for k
     */
    int cofactor_mode;

    /************
     * ECDH KDF *
     ************/
    /* KDF (if any) to use for ECDH */
    enum kdf_type kdf_type;
    /* Message digest to use for key derivation */
    EVP_MD *kdf_md;
    /* User key material */
    unsigned char *kdf_ukm;
    size_t kdf_ukmlen;
    /* KDF output length */
    size_t kdf_outlen;
    OSSL_FIPS_IND_DECLARE
} PROV_ECDH_CTX;

static void *ecdh_newctx(void *provctx)
{
    PROV_ECDH_CTX *pectx;

    if (!ossl_prov_is_running())
        return NULL;

    pectx = OPENSSL_zalloc(sizeof(*pectx));
    if (pectx == NULL)
        return NULL;

    pectx->libctx = PROV_LIBCTX_OF(provctx);
    pectx->cofactor_mode = -1;
    pectx->kdf_type = PROV_ECDH_KDF_NONE;
    OSSL_FIPS_IND_INIT(pectx)

    return (void *)pectx;
}

static int ecdh_init(void *vpecdhctx, void *vecdh, const OSSL_PARAM params[])
{
    PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;

    if (!ossl_prov_is_running()
        || pecdhctx == NULL
        || vecdh == NULL
        || (EC_KEY_get0_group(vecdh) == NULL)
        || !EC_KEY_up_ref(vecdh))
        return 0;
    EC_KEY_free(pecdhctx->k);
    pecdhctx->k = vecdh;
    pecdhctx->cofactor_mode = -1;
    pecdhctx->kdf_type = PROV_ECDH_KDF_NONE;

    OSSL_FIPS_IND_SET_APPROVED(pecdhctx)
    if (!ecdh_set_ctx_params(pecdhctx, params))
        return 0;
#ifdef FIPS_MODULE
    if (!ossl_fips_ind_ec_key_check(OSSL_FIPS_IND_GET(pecdhctx),
            OSSL_FIPS_IND_SETTABLE0, pecdhctx->libctx,
            EC_KEY_get0_group(vecdh), "ECDH Init", 1))
        return 0;
#endif
    return 1;
}

static int ecdh_match_params(const EC_KEY *priv, const EC_KEY *peer)
{
    int ret;
    BN_CTX *ctx = NULL;
    const EC_GROUP *group_priv = EC_KEY_get0_group(priv);
    const EC_GROUP *group_peer = EC_KEY_get0_group(peer);

    ctx = BN_CTX_new_ex(ossl_ec_key_get_libctx(priv));
    if (ctx == NULL) {
        ERR_raise(ERR_LIB_PROV, ERR_R_BN_LIB);
        return 0;
    }
    ret = group_priv != NULL
        && group_peer != NULL
        && EC_GROUP_cmp(group_priv, group_peer, ctx) == 0;
    if (!ret)
        ERR_raise(ERR_LIB_PROV, PROV_R_MISMATCHING_DOMAIN_PARAMETERS);
    BN_CTX_free(ctx);
    return ret;
}

static int ecdh_set_peer(void *vpecdhctx, void *vecdh)
{
    PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;

    if (!ossl_prov_is_running()
        || pecdhctx == NULL
        || vecdh == NULL
        || !ecdh_match_params(pecdhctx->k, vecdh))
        return 0;
#ifdef FIPS_MODULE
    if (!ossl_fips_ind_ec_key_check(OSSL_FIPS_IND_GET(pecdhctx),
            OSSL_FIPS_IND_SETTABLE0, pecdhctx->libctx,
            EC_KEY_get0_group(vecdh), "ECDH Set Peer",
            1))
        return 0;
#endif
    if (!EC_KEY_up_ref(vecdh))
        return 0;

    EC_KEY_free(pecdhctx->peerk);
    pecdhctx->peerk = vecdh;
    return 1;
}

static void ecdh_freectx(void *vpecdhctx)
{
    PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;

    EC_KEY_free(pecdhctx->k);
    EC_KEY_free(pecdhctx->peerk);

    EVP_MD_free(pecdhctx->kdf_md);
    OPENSSL_clear_free(pecdhctx->kdf_ukm, pecdhctx->kdf_ukmlen);

    OPENSSL_free(pecdhctx);
}

static void *ecdh_dupctx(void *vpecdhctx)
{
    PROV_ECDH_CTX *srcctx = (PROV_ECDH_CTX *)vpecdhctx;
    PROV_ECDH_CTX *dstctx;

    if (!ossl_prov_is_running())
        return NULL;

    dstctx = OPENSSL_zalloc(sizeof(*srcctx));
    if (dstctx == NULL)
        return NULL;

    *dstctx = *srcctx;

    /* clear all pointers */

    dstctx->k = NULL;
    dstctx->peerk = NULL;
    dstctx->kdf_md = NULL;
    dstctx->kdf_ukm = NULL;

    /* up-ref all ref-counted objects referenced in dstctx */

    if (srcctx->k != NULL && !EC_KEY_up_ref(srcctx->k))
        goto err;
    else
        dstctx->k = srcctx->k;

    if (srcctx->peerk != NULL && !EC_KEY_up_ref(srcctx->peerk))
        goto err;
    else
        dstctx->peerk = srcctx->peerk;

    if (srcctx->kdf_md != NULL && !EVP_MD_up_ref(srcctx->kdf_md))
        goto err;
    else
        dstctx->kdf_md = srcctx->kdf_md;

    /* Duplicate UKM data if present */
    if (srcctx->kdf_ukm != NULL && srcctx->kdf_ukmlen > 0) {
        dstctx->kdf_ukm = OPENSSL_memdup(srcctx->kdf_ukm,
            srcctx->kdf_ukmlen);
        if (dstctx->kdf_ukm == NULL)
            goto err;
    }

    return dstctx;

err:
    ecdh_freectx(dstctx);
    return NULL;
}

static int ecdh_set_ctx_params(void *vpecdhctx, const OSSL_PARAM params[])
{
    char name[80] = { '\0' }; /* should be big enough */
    char *str = NULL;
    PROV_ECDH_CTX *pectx = (PROV_ECDH_CTX *)vpecdhctx;
    const OSSL_PARAM *p;

    if (pectx == NULL)
        return 0;
    if (ossl_param_is_empty(params))
        return 1;

    if (!OSSL_FIPS_IND_SET_CTX_PARAM(pectx, OSSL_FIPS_IND_SETTABLE0, params,
            OSSL_EXCHANGE_PARAM_FIPS_KEY_CHECK))
        return 0;
    if (!OSSL_FIPS_IND_SET_CTX_PARAM(pectx, OSSL_FIPS_IND_SETTABLE1, params,
            OSSL_EXCHANGE_PARAM_FIPS_DIGEST_CHECK))
        return 0;
    if (!OSSL_FIPS_IND_SET_CTX_PARAM(pectx, OSSL_FIPS_IND_SETTABLE2, params,
            OSSL_EXCHANGE_PARAM_FIPS_ECDH_COFACTOR_CHECK))
        return 0;

    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE);
    if (p != NULL) {
        int mode;

        if (!OSSL_PARAM_get_int(p, &mode))
            return 0;

        if (mode < -1 || mode > 1)
            return 0;

        pectx->cofactor_mode = mode;
    }

    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
    if (p != NULL) {
        str = name;
        if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
            return 0;

        if (name[0] == '\0')
            pectx->kdf_type = PROV_ECDH_KDF_NONE;
        else if (strcmp(name, OSSL_KDF_NAME_X963KDF) == 0)
            pectx->kdf_type = PROV_ECDH_KDF_X9_63;
        else
            return 0;
    }

    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
    if (p != NULL) {
        char mdprops[80] = { '\0' }; /* should be big enough */

        str = name;
        if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
            return 0;

        str = mdprops;
        p = OSSL_PARAM_locate_const(params,
            OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS);

        if (p != NULL) {
            if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(mdprops)))
                return 0;
        }

        EVP_MD_free(pectx->kdf_md);
        pectx->kdf_md = EVP_MD_fetch(pectx->libctx, name, mdprops);
        if (pectx->kdf_md == NULL)
            return 0;
        /* XOF digests are not allowed */
        if (EVP_MD_xof(pectx->kdf_md)) {
            ERR_raise(ERR_LIB_PROV, PROV_R_XOF_DIGESTS_NOT_ALLOWED);
            return 0;
        }
#ifdef FIPS_MODULE
        if (!ossl_fips_ind_digest_exch_check(OSSL_FIPS_IND_GET(pectx),
                OSSL_FIPS_IND_SETTABLE1, pectx->libctx,
                pectx->kdf_md, "ECDH Set Ctx")) {
            EVP_MD_free(pectx->kdf_md);
            pectx->kdf_md = NULL;
            return 0;
        }
#endif
    }

    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
    if (p != NULL) {
        size_t outlen;

        if (!OSSL_PARAM_get_size_t(p, &outlen))
            return 0;
        pectx->kdf_outlen = outlen;
    }

    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
    if (p != NULL) {
        void *tmp_ukm = NULL;
        size_t tmp_ukmlen;

        if (!OSSL_PARAM_get_octet_string(p, &tmp_ukm, 0, &tmp_ukmlen))
            return 0;
        OPENSSL_free(pectx->kdf_ukm);
        pectx->kdf_ukm = tmp_ukm;
        pectx->kdf_ukmlen = tmp_ukmlen;
    }

    return 1;
}

static const OSSL_PARAM known_settable_ctx_params[] = {
    OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE, NULL),
    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS, NULL, 0),
    OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
    OSSL_PARAM_octet_string(OSSL_EXCHANGE_PARAM_KDF_UKM, NULL, 0),
    OSSL_FIPS_IND_SETTABLE_CTX_PARAM(OSSL_EXCHANGE_PARAM_FIPS_KEY_CHECK)
        OSSL_FIPS_IND_SETTABLE_CTX_PARAM(OSSL_EXCHANGE_PARAM_FIPS_DIGEST_CHECK)
            OSSL_FIPS_IND_SETTABLE_CTX_PARAM(OSSL_EXCHANGE_PARAM_FIPS_ECDH_COFACTOR_CHECK)
                OSSL_PARAM_END
};

static const OSSL_PARAM *ecdh_settable_ctx_params(ossl_unused void *vpecdhctx,
    ossl_unused void *provctx)
{
    return known_settable_ctx_params;
}

static int ecdh_get_ctx_params(void *vpecdhctx, OSSL_PARAM params[])
{
    PROV_ECDH_CTX *pectx = (PROV_ECDH_CTX *)vpecdhctx;
    OSSL_PARAM *p;

    if (pectx == NULL)
        return 0;

    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE);
    if (p != NULL) {
        int mode = pectx->cofactor_mode;

        if (mode == -1) {
            /* check what is the default for pecdhctx->k */
            mode = EC_KEY_get_flags(pectx->k) & EC_FLAG_COFACTOR_ECDH ? 1 : 0;
        }

        if (!OSSL_PARAM_set_int(p, mode))
            return 0;
    }

    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
    if (p != NULL) {
        const char *kdf_type = NULL;

        switch (pectx->kdf_type) {
        case PROV_ECDH_KDF_NONE:
            kdf_type = "";
            break;
        case PROV_ECDH_KDF_X9_63:
            kdf_type = OSSL_KDF_NAME_X963KDF;
            break;
        default:
            return 0;
        }

        if (!OSSL_PARAM_set_utf8_string(p, kdf_type))
            return 0;
    }

    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
    if (p != NULL
        && !OSSL_PARAM_set_utf8_string(p, pectx->kdf_md == NULL ? "" : EVP_MD_get0_name(pectx->kdf_md))) {
        return 0;
    }

    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
    if (p != NULL && !OSSL_PARAM_set_size_t(p, pectx->kdf_outlen))
        return 0;

    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
    if (p != NULL && !OSSL_PARAM_set_octet_ptr(p, pectx->kdf_ukm, pectx->kdf_ukmlen))
        return 0;
    if (!OSSL_FIPS_IND_GET_CTX_PARAM(pectx, params))
        return 0;
    return 1;
}

static const OSSL_PARAM known_gettable_ctx_params[] = {
    OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE, NULL),
    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
    OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
    OSSL_PARAM_DEFN(OSSL_EXCHANGE_PARAM_KDF_UKM, OSSL_PARAM_OCTET_PTR,
        NULL, 0),
    OSSL_FIPS_IND_GETTABLE_CTX_PARAM()
        OSSL_PARAM_END
};

static const OSSL_PARAM *ecdh_gettable_ctx_params(ossl_unused void *vpecdhctx,
    ossl_unused void *provctx)
{
    return known_gettable_ctx_params;
}

static ossl_inline
    size_t
    ecdh_size(const EC_KEY *k)
{
    size_t degree = 0;
    const EC_GROUP *group;

    if (k == NULL
        || (group = EC_KEY_get0_group(k)) == NULL)
        return 0;

    degree = EC_GROUP_get_degree(group);

    return (degree + 7) / 8;
}

static ossl_inline int ecdh_plain_derive(void *vpecdhctx, unsigned char *secret,
    size_t *psecretlen, size_t outlen)
{
    PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;
    int retlen, ret = 0;
    size_t ecdhsize, size;
    const EC_POINT *ppubkey = NULL;
    EC_KEY *privk = NULL;
    const EC_GROUP *group;
    const BIGNUM *cofactor;
    int key_cofactor_mode;
    int has_cofactor;
#ifdef FIPS_MODULE
    int cofactor_approved = 0;
#endif

    if (pecdhctx->k == NULL || pecdhctx->peerk == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
        return 0;
    }

    ecdhsize = ecdh_size(pecdhctx->k);
    if (secret == NULL) {
        *psecretlen = ecdhsize;
        return 1;
    }

    if ((group = EC_KEY_get0_group(pecdhctx->k)) == NULL
        || (cofactor = EC_GROUP_get0_cofactor(group)) == NULL)
        return 0;

    has_cofactor = !BN_is_one(cofactor);

    /*
     * NB: unlike PKCS#3 DH, if outlen is less than maximum size this is not
     * an error, the result is truncated.
     */
    size = outlen < ecdhsize ? outlen : ecdhsize;

    /*
     * The ctx->cofactor_mode flag has precedence over the
     * cofactor_mode flag set on ctx->k.
     *
     * - if ctx->cofactor_mode == -1, use ctx->k directly
     * - if ctx->cofactor_mode == key_cofactor_mode, use ctx->k directly
     * - if ctx->cofactor_mode != key_cofactor_mode:
     *     - if ctx->k->cofactor == 1, the cofactor_mode flag is irrelevant, use
     *          ctx->k directly
     *     - if ctx->k->cofactor != 1, use a duplicate of ctx->k with the flag
     *          set to ctx->cofactor_mode
     */
    key_cofactor_mode = (EC_KEY_get_flags(pecdhctx->k) & EC_FLAG_COFACTOR_ECDH) ? 1 : 0;
    if (pecdhctx->cofactor_mode != -1
        && pecdhctx->cofactor_mode != key_cofactor_mode
        && has_cofactor) {
        if ((privk = EC_KEY_dup(pecdhctx->k)) == NULL)
            return 0;

        if (pecdhctx->cofactor_mode == 1) {
            EC_KEY_set_flags(privk, EC_FLAG_COFACTOR_ECDH);
#ifdef FIPS_MODULE
            cofactor_approved = 1;
#endif
        } else {
            EC_KEY_clear_flags(privk, EC_FLAG_COFACTOR_ECDH);
        }
    } else {
        privk = pecdhctx->k;
#ifdef FIPS_MODULE
        cofactor_approved = key_cofactor_mode;
#endif
    }

#ifdef FIPS_MODULE
    /*
     * SP800-56A r3 Section 5.7.1.2 requires ECC Cofactor DH to be used.
     * This applies to the 'B' and 'K' curves that have cofactors that are not 1.
     */
    if (has_cofactor && !cofactor_approved) {
        if (!OSSL_FIPS_IND_ON_UNAPPROVED(pecdhctx, OSSL_FIPS_IND_SETTABLE2,
                pecdhctx->libctx, "ECDH", "Cofactor",
                ossl_fips_config_ecdh_cofactor_check)) {
            ERR_raise(ERR_LIB_PROV, PROV_R_COFACTOR_REQUIRED);
            goto end;
        }
    }
#endif

    ppubkey = EC_KEY_get0_public_key(pecdhctx->peerk);

    retlen = ECDH_compute_key(secret, size, ppubkey, privk, NULL);

    if (retlen <= 0)
        goto end;

    *psecretlen = retlen;
    ret = 1;

end:
    if (privk != pecdhctx->k)
        EC_KEY_free(privk);
    return ret;
}

static ossl_inline int ecdh_X9_63_kdf_derive(void *vpecdhctx, unsigned char *secret,
    size_t *psecretlen, size_t outlen)
{
    PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;
    unsigned char *stmp = NULL;
    size_t stmplen;
    int ret = 0;

    if (secret == NULL) {
        *psecretlen = pecdhctx->kdf_outlen;
        return 1;
    }

    if (pecdhctx->kdf_outlen > outlen) {
        ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
        return 0;
    }
    if (!ecdh_plain_derive(vpecdhctx, NULL, &stmplen, 0))
        return 0;
    if ((stmp = OPENSSL_secure_malloc(stmplen)) == NULL)
        return 0;
    if (!ecdh_plain_derive(vpecdhctx, stmp, &stmplen, stmplen))
        goto err;

    /* Do KDF stuff */
    if (!ossl_ecdh_kdf_X9_63(secret, pecdhctx->kdf_outlen,
            stmp, stmplen,
            pecdhctx->kdf_ukm,
            pecdhctx->kdf_ukmlen,
            pecdhctx->kdf_md,
            pecdhctx->libctx, NULL))
        goto err;
    *psecretlen = pecdhctx->kdf_outlen;
    ret = 1;

err:
    OPENSSL_secure_clear_free(stmp, stmplen);
    return ret;
}

static int ecdh_derive(void *vpecdhctx, unsigned char *secret,
    size_t *psecretlen, size_t outlen)
{
    PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;

    switch (pecdhctx->kdf_type) {
    case PROV_ECDH_KDF_NONE:
        return ecdh_plain_derive(vpecdhctx, secret, psecretlen, outlen);
    case PROV_ECDH_KDF_X9_63:
        return ecdh_X9_63_kdf_derive(vpecdhctx, secret, psecretlen, outlen);
    default:
        break;
    }
    return 0;
}

const OSSL_DISPATCH ossl_ecdh_keyexch_functions[] = {
    { OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))ecdh_newctx },
    { OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))ecdh_init },
    { OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))ecdh_derive },
    { OSSL_FUNC_KEYEXCH_SET_PEER, (void (*)(void))ecdh_set_peer },
    { OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))ecdh_freectx },
    { OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))ecdh_dupctx },
    { OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS, (void (*)(void))ecdh_set_ctx_params },
    { OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS,
        (void (*)(void))ecdh_settable_ctx_params },
    { OSSL_FUNC_KEYEXCH_GET_CTX_PARAMS, (void (*)(void))ecdh_get_ctx_params },
    { OSSL_FUNC_KEYEXCH_GETTABLE_CTX_PARAMS,
        (void (*)(void))ecdh_gettable_ctx_params },
    OSSL_DISPATCH_END
};

Coverage Report

Created: 2025-12-31 06:58

Line	Count	Source
1		/*
2		* Copyright 2020-2024 The OpenSSL Project Authors. All Rights Reserved.
3		*
4		* Licensed under the Apache License 2.0 (the "License"). You may not use
5		* this file except in compliance with the License. You can obtain a copy
6		* in the file LICENSE in the source distribution or at
7		* https://www.openssl.org/source/license.html
8		*/
9
10		/*
11		* ECDH low level APIs are deprecated for public use, but still ok for
12		* internal use.
13		*/
14		#include "internal/deprecated.h"
15
16		#include <string.h>
17		#include <openssl/crypto.h>
18		#include <openssl/evp.h>
19		#include <openssl/core_dispatch.h>
20		#include <openssl/core_names.h>
21		#include <openssl/ec.h>
22		#include <openssl/params.h>
23		#include <openssl/err.h>
24		#include <openssl/proverr.h>
25		#include "prov/provider_ctx.h"
26		#include "prov/providercommon.h"
27		#include "prov/implementations.h"
28		#include "prov/securitycheck.h"
29		#include "crypto/ec.h" /* ossl_ecdh_kdf_X9_63() */
30
31		static OSSL_FUNC_keyexch_newctx_fn ecdh_newctx;
32		static OSSL_FUNC_keyexch_init_fn ecdh_init;
33		static OSSL_FUNC_keyexch_set_peer_fn ecdh_set_peer;
34		static OSSL_FUNC_keyexch_derive_fn ecdh_derive;
35		static OSSL_FUNC_keyexch_freectx_fn ecdh_freectx;
36		static OSSL_FUNC_keyexch_dupctx_fn ecdh_dupctx;
37		static OSSL_FUNC_keyexch_set_ctx_params_fn ecdh_set_ctx_params;
38		static OSSL_FUNC_keyexch_settable_ctx_params_fn ecdh_settable_ctx_params;
39		static OSSL_FUNC_keyexch_get_ctx_params_fn ecdh_get_ctx_params;
40		static OSSL_FUNC_keyexch_gettable_ctx_params_fn ecdh_gettable_ctx_params;
41
42		enum kdf_type {
43		PROV_ECDH_KDF_NONE = 0,
44		PROV_ECDH_KDF_X9_63
45		};
46
47		/*
48		* What's passed as an actual key is defined by the KEYMGMT interface.
49		* We happen to know that our KEYMGMT simply passes EC_KEY structures, so
50		* we use that here too.
51		*/
52
53		typedef struct {
54		OSSL_LIB_CTX *libctx;
55
56		EC_KEY *k;
57		EC_KEY *peerk;
58
59		/*
60		* ECDH cofactor mode:
61		*
62		* . 0 disabled
63		* . 1 enabled
64		* . -1 use cofactor mode set for k
65		*/
66		int cofactor_mode;
67
68		/************
69		* ECDH KDF *
70		************/
71		/* KDF (if any) to use for ECDH */
72		enum kdf_type kdf_type;
73		/* Message digest to use for key derivation */
74		EVP_MD *kdf_md;
75		/* User key material */
76		unsigned char *kdf_ukm;
77		size_t kdf_ukmlen;
78		/* KDF output length */
79		size_t kdf_outlen;
80		OSSL_FIPS_IND_DECLARE
81		} PROV_ECDH_CTX;
82
83		static void ecdh_newctx(void provctx)
84	4.31k	{
85	4.31k	PROV_ECDH_CTX *pectx;
86
87	4.31k	if (!ossl_prov_is_running())
88	0	return NULL;
89
90	4.31k	pectx = OPENSSL_zalloc(sizeof(*pectx));
91	4.31k	if (pectx == NULL)
92	0	return NULL;
93
94	4.31k	pectx->libctx = PROV_LIBCTX_OF(provctx);
95	4.31k	pectx->cofactor_mode = -1;
96	4.31k	pectx->kdf_type = PROV_ECDH_KDF_NONE;
97	4.31k	OSSL_FIPS_IND_INIT(pectx)
98
99	4.31k	return (void *)pectx;
100	4.31k	}
101
102		static int ecdh_init(void vpecdhctx, void vecdh, const OSSL_PARAM params[])
103	3.04k	{
104	3.04k	PROV_ECDH_CTX pecdhctx = (PROV_ECDH_CTX )vpecdhctx;
105
106	3.04k	if (!ossl_prov_is_running()
107	3.04k	\|\| pecdhctx == NULL
108	3.04k	\|\| vecdh == NULL
109	3.04k	\|\| (EC_KEY_get0_group(vecdh) == NULL)
110	3.04k	\|\| !EC_KEY_up_ref(vecdh))
111	0	return 0;
112	3.04k	EC_KEY_free(pecdhctx->k);
113	3.04k	pecdhctx->k = vecdh;
114	3.04k	pecdhctx->cofactor_mode = -1;
115	3.04k	pecdhctx->kdf_type = PROV_ECDH_KDF_NONE;
116
117	3.04k	OSSL_FIPS_IND_SET_APPROVED(pecdhctx)
118	3.04k	if (!ecdh_set_ctx_params(pecdhctx, params))
119	0	return 0;
120		#ifdef FIPS_MODULE
121		if (!ossl_fips_ind_ec_key_check(OSSL_FIPS_IND_GET(pecdhctx),
122		OSSL_FIPS_IND_SETTABLE0, pecdhctx->libctx,
123		EC_KEY_get0_group(vecdh), "ECDH Init", 1))
124		return 0;
125		#endif
126	3.04k	return 1;
127	3.04k	}
128
129		static int ecdh_match_params(const EC_KEY priv, const EC_KEY peer)
130	4.28k	{
131	4.28k	int ret;
132	4.28k	BN_CTX *ctx = NULL;
133	4.28k	const EC_GROUP *group_priv = EC_KEY_get0_group(priv);
134	4.28k	const EC_GROUP *group_peer = EC_KEY_get0_group(peer);
135
136	4.28k	ctx = BN_CTX_new_ex(ossl_ec_key_get_libctx(priv));
137	4.28k	if (ctx == NULL) {
138	0	ERR_raise(ERR_LIB_PROV, ERR_R_BN_LIB);
139	0	return 0;
140	0	}
141	4.28k	ret = group_priv != NULL
142	4.28k	&& group_peer != NULL
143	4.28k	&& EC_GROUP_cmp(group_priv, group_peer, ctx) == 0;
144	4.28k	if (!ret)
145	4.28k	ERR_raise(ERR_LIB_PROV, PROV_R_MISMATCHING_DOMAIN_PARAMETERS);
146	4.28k	BN_CTX_free(ctx);
147	4.28k	return ret;
148	4.28k	}
149
150		static int ecdh_set_peer(void vpecdhctx, void vecdh)
151	3.02k	{
152	3.02k	PROV_ECDH_CTX pecdhctx = (PROV_ECDH_CTX )vpecdhctx;
153
154	3.02k	if (!ossl_prov_is_running()
155	3.02k	\|\| pecdhctx == NULL
156	3.02k	\|\| vecdh == NULL
157	3.02k	\|\| !ecdh_match_params(pecdhctx->k, vecdh))
158	0	return 0;
159		#ifdef FIPS_MODULE
160		if (!ossl_fips_ind_ec_key_check(OSSL_FIPS_IND_GET(pecdhctx),
161		OSSL_FIPS_IND_SETTABLE0, pecdhctx->libctx,
162		EC_KEY_get0_group(vecdh), "ECDH Set Peer",
163		1))
164		return 0;
165		#endif
166	3.02k	if (!EC_KEY_up_ref(vecdh))
167	0	return 0;
168
169	3.02k	EC_KEY_free(pecdhctx->peerk);
170	3.02k	pecdhctx->peerk = vecdh;
171	3.02k	return 1;
172	3.02k	}
173
174		static void ecdh_freectx(void *vpecdhctx)
175	4.31k	{
176	4.31k	PROV_ECDH_CTX pecdhctx = (PROV_ECDH_CTX )vpecdhctx;
177
178	4.31k	EC_KEY_free(pecdhctx->k);
179	4.31k	EC_KEY_free(pecdhctx->peerk);
180
181	4.31k	EVP_MD_free(pecdhctx->kdf_md);
182	4.31k	OPENSSL_clear_free(pecdhctx->kdf_ukm, pecdhctx->kdf_ukmlen);
183
184	4.31k	OPENSSL_free(pecdhctx);
185	4.31k	}
186
187		static void ecdh_dupctx(void vpecdhctx)
188	0	{
189	0	PROV_ECDH_CTX srcctx = (PROV_ECDH_CTX )vpecdhctx;
190	0	PROV_ECDH_CTX *dstctx;
191
192	0	if (!ossl_prov_is_running())
193	0	return NULL;
194
195	0	dstctx = OPENSSL_zalloc(sizeof(*srcctx));
196	0	if (dstctx == NULL)
197	0	return NULL;
198
199	0	dstctx = srcctx;
200
201		/* clear all pointers */
202
203	0	dstctx->k = NULL;
204	0	dstctx->peerk = NULL;
205	0	dstctx->kdf_md = NULL;
206	0	dstctx->kdf_ukm = NULL;
207
208		/* up-ref all ref-counted objects referenced in dstctx */
209
210	0	if (srcctx->k != NULL && !EC_KEY_up_ref(srcctx->k))
211	0	goto err;
212	0	else
213	0	dstctx->k = srcctx->k;
214
215	0	if (srcctx->peerk != NULL && !EC_KEY_up_ref(srcctx->peerk))
216	0	goto err;
217	0	else
218	0	dstctx->peerk = srcctx->peerk;
219
220	0	if (srcctx->kdf_md != NULL && !EVP_MD_up_ref(srcctx->kdf_md))
221	0	goto err;
222	0	else
223	0	dstctx->kdf_md = srcctx->kdf_md;
224
225		/* Duplicate UKM data if present */
226	0	if (srcctx->kdf_ukm != NULL && srcctx->kdf_ukmlen > 0) {
227	0	dstctx->kdf_ukm = OPENSSL_memdup(srcctx->kdf_ukm,
228	0	srcctx->kdf_ukmlen);
229	0	if (dstctx->kdf_ukm == NULL)
230	0	goto err;
231	0	}
232
233	0	return dstctx;
234
235	0	err:
236	0	ecdh_freectx(dstctx);
237	0	return NULL;
238	0	}
239
240		static int ecdh_set_ctx_params(void *vpecdhctx, const OSSL_PARAM params[])
241	752	{
242	752	char name[80] = { '\0' }; /* should be big enough */
243	752	char *str = NULL;
244	752	PROV_ECDH_CTX pectx = (PROV_ECDH_CTX )vpecdhctx;
245	752	const OSSL_PARAM *p;
246
247	752	if (pectx == NULL)
248	0	return 0;
249	752	if (ossl_param_is_empty(params))
250	752	return 1;
251
252	0	if (!OSSL_FIPS_IND_SET_CTX_PARAM(pectx, OSSL_FIPS_IND_SETTABLE0, params,
253	0	OSSL_EXCHANGE_PARAM_FIPS_KEY_CHECK))
254	0	return 0;
255	0	if (!OSSL_FIPS_IND_SET_CTX_PARAM(pectx, OSSL_FIPS_IND_SETTABLE1, params,
256	0	OSSL_EXCHANGE_PARAM_FIPS_DIGEST_CHECK))
257	0	return 0;
258	0	if (!OSSL_FIPS_IND_SET_CTX_PARAM(pectx, OSSL_FIPS_IND_SETTABLE2, params,
259	0	OSSL_EXCHANGE_PARAM_FIPS_ECDH_COFACTOR_CHECK))
260	0	return 0;
261
262	0	p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE);
263	0	if (p != NULL) {
264	0	int mode;
265
266	0	if (!OSSL_PARAM_get_int(p, &mode))
267	0	return 0;
268
269	0	if (mode < -1 \|\| mode > 1)
270	0	return 0;
271
272	0	pectx->cofactor_mode = mode;
273	0	}
274
275	0	p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
276	0	if (p != NULL) {
277	0	str = name;
278	0	if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
279	0	return 0;
280
281	0	if (name[0] == '\0')
282	0	pectx->kdf_type = PROV_ECDH_KDF_NONE;
283	0	else if (strcmp(name, OSSL_KDF_NAME_X963KDF) == 0)
284	0	pectx->kdf_type = PROV_ECDH_KDF_X9_63;
285	0	else
286	0	return 0;
287	0	}
288
289	0	p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
290	0	if (p != NULL) {
291	0	char mdprops[80] = { '\0' }; /* should be big enough */
292
293	0	str = name;
294	0	if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
295	0	return 0;
296
297	0	str = mdprops;
298	0	p = OSSL_PARAM_locate_const(params,
299	0	OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS);
300
301	0	if (p != NULL) {
302	0	if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(mdprops)))
303	0	return 0;
304	0	}
305
306	0	EVP_MD_free(pectx->kdf_md);
307	0	pectx->kdf_md = EVP_MD_fetch(pectx->libctx, name, mdprops);
308	0	if (pectx->kdf_md == NULL)
309	0	return 0;
310		/* XOF digests are not allowed */
311	0	if (EVP_MD_xof(pectx->kdf_md)) {
312	0	ERR_raise(ERR_LIB_PROV, PROV_R_XOF_DIGESTS_NOT_ALLOWED);
313	0	return 0;
314	0	}
315		#ifdef FIPS_MODULE
316		if (!ossl_fips_ind_digest_exch_check(OSSL_FIPS_IND_GET(pectx),
317		OSSL_FIPS_IND_SETTABLE1, pectx->libctx,
318		pectx->kdf_md, "ECDH Set Ctx")) {
319		EVP_MD_free(pectx->kdf_md);
320		pectx->kdf_md = NULL;
321		return 0;
322		}
323		#endif
324	0	}
325
326	0	p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
327	0	if (p != NULL) {
328	0	size_t outlen;
329
330	0	if (!OSSL_PARAM_get_size_t(p, &outlen))
331	0	return 0;
332	0	pectx->kdf_outlen = outlen;
333	0	}
334
335	0	p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
336	0	if (p != NULL) {
337	0	void *tmp_ukm = NULL;
338	0	size_t tmp_ukmlen;
339
340	0	if (!OSSL_PARAM_get_octet_string(p, &tmp_ukm, 0, &tmp_ukmlen))
341	0	return 0;
342	0	OPENSSL_free(pectx->kdf_ukm);
343	0	pectx->kdf_ukm = tmp_ukm;
344	0	pectx->kdf_ukmlen = tmp_ukmlen;
345	0	}
346
347	0	return 1;
348	0	}
349
350		static const OSSL_PARAM known_settable_ctx_params[] = {
351		OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE, NULL),
352		OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
353		OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
354		OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS, NULL, 0),
355		OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
356		OSSL_PARAM_octet_string(OSSL_EXCHANGE_PARAM_KDF_UKM, NULL, 0),
357		OSSL_FIPS_IND_SETTABLE_CTX_PARAM(OSSL_EXCHANGE_PARAM_FIPS_KEY_CHECK)
358		OSSL_FIPS_IND_SETTABLE_CTX_PARAM(OSSL_EXCHANGE_PARAM_FIPS_DIGEST_CHECK)
359		OSSL_FIPS_IND_SETTABLE_CTX_PARAM(OSSL_EXCHANGE_PARAM_FIPS_ECDH_COFACTOR_CHECK)
360		OSSL_PARAM_END
361		};
362
363		static const OSSL_PARAM ecdh_settable_ctx_params(ossl_unused void vpecdhctx,
364		ossl_unused void *provctx)
365	25	{
366	25	return known_settable_ctx_params;
367	25	}
368
369		static int ecdh_get_ctx_params(void *vpecdhctx, OSSL_PARAM params[])
370	0	{
371	0	PROV_ECDH_CTX pectx = (PROV_ECDH_CTX )vpecdhctx;
372	0	OSSL_PARAM *p;
373
374	0	if (pectx == NULL)
375	0	return 0;
376
377	0	p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE);
378	0	if (p != NULL) {
379	0	int mode = pectx->cofactor_mode;
380
381	0	if (mode == -1) {
382		/* check what is the default for pecdhctx->k */
383	0	mode = EC_KEY_get_flags(pectx->k) & EC_FLAG_COFACTOR_ECDH ? 1 : 0;
384	0	}
385
386	0	if (!OSSL_PARAM_set_int(p, mode))
387	0	return 0;
388	0	}
389
390	0	p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
391	0	if (p != NULL) {
392	0	const char *kdf_type = NULL;
393
394	0	switch (pectx->kdf_type) {
395	0	case PROV_ECDH_KDF_NONE:
396	0	kdf_type = "";
397	0	break;
398	0	case PROV_ECDH_KDF_X9_63:
399	0	kdf_type = OSSL_KDF_NAME_X963KDF;
400	0	break;
401	0	default:
402	0	return 0;
403	0	}
404
405	0	if (!OSSL_PARAM_set_utf8_string(p, kdf_type))
406	0	return 0;
407	0	}
408
409	0	p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
410	0	if (p != NULL
411	0	&& !OSSL_PARAM_set_utf8_string(p, pectx->kdf_md == NULL ? "" : EVP_MD_get0_name(pectx->kdf_md))) {
412	0	return 0;
413	0	}
414
415	0	p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
416	0	if (p != NULL && !OSSL_PARAM_set_size_t(p, pectx->kdf_outlen))
417	0	return 0;
418
419	0	p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
420	0	if (p != NULL && !OSSL_PARAM_set_octet_ptr(p, pectx->kdf_ukm, pectx->kdf_ukmlen))
421	0	return 0;
422	0	if (!OSSL_FIPS_IND_GET_CTX_PARAM(pectx, params))
423	0	return 0;
424	0	return 1;
425	0	}
426
427		static const OSSL_PARAM known_gettable_ctx_params[] = {
428		OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE, NULL),
429		OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
430		OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
431		OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
432		OSSL_PARAM_DEFN(OSSL_EXCHANGE_PARAM_KDF_UKM, OSSL_PARAM_OCTET_PTR,
433		NULL, 0),
434		OSSL_FIPS_IND_GETTABLE_CTX_PARAM()
435		OSSL_PARAM_END
436		};
437
438		static const OSSL_PARAM ecdh_gettable_ctx_params(ossl_unused void vpecdhctx,
439		ossl_unused void *provctx)
440	0	{
441	0	return known_gettable_ctx_params;
442	0	}
443
444		static ossl_inline
445		size_t
446		ecdh_size(const EC_KEY *k)
447	8.57k	{
448	8.57k	size_t degree = 0;
449	8.57k	const EC_GROUP *group;
450
451	8.57k	if (k == NULL
452	8.57k	\|\| (group = EC_KEY_get0_group(k)) == NULL)
453	0	return 0;
454
455	8.57k	degree = EC_GROUP_get_degree(group);
456
457	8.57k	return (degree + 7) / 8;
458	8.57k	}
459
460		static ossl_inline int ecdh_plain_derive(void vpecdhctx, unsigned char secret,
461		size_t *psecretlen, size_t outlen)
462	6.04k	{
463	6.04k	PROV_ECDH_CTX pecdhctx = (PROV_ECDH_CTX )vpecdhctx;
464	6.04k	int retlen, ret = 0;
465	6.04k	size_t ecdhsize, size;
466	6.04k	const EC_POINT *ppubkey = NULL;
467	6.04k	EC_KEY *privk = NULL;
468	6.04k	const EC_GROUP *group;
469	6.04k	const BIGNUM *cofactor;
470	6.04k	int key_cofactor_mode;
471	6.04k	int has_cofactor;
472		#ifdef FIPS_MODULE
473		int cofactor_approved = 0;
474		#endif
475
476	6.04k	if (pecdhctx->k == NULL \|\| pecdhctx->peerk == NULL) {
477	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
478	0	return 0;
479	0	}
480
481	6.04k	ecdhsize = ecdh_size(pecdhctx->k);
482	6.04k	if (secret == NULL) {
483	3.02k	*psecretlen = ecdhsize;
484	3.02k	return 1;
485	3.02k	}
486
487	3.02k	if ((group = EC_KEY_get0_group(pecdhctx->k)) == NULL
488	3.02k	\|\| (cofactor = EC_GROUP_get0_cofactor(group)) == NULL)
489	0	return 0;
490
491	3.02k	has_cofactor = !BN_is_one(cofactor);
492
493		/*
494		* NB: unlike PKCS#3 DH, if outlen is less than maximum size this is not
495		* an error, the result is truncated.
496		*/
497	3.02k	size = outlen < ecdhsize ? outlen : ecdhsize;
498
499		/*
500		* The ctx->cofactor_mode flag has precedence over the
501		* cofactor_mode flag set on ctx->k.
502		*
503		* - if ctx->cofactor_mode == -1, use ctx->k directly
504		* - if ctx->cofactor_mode == key_cofactor_mode, use ctx->k directly
505		* - if ctx->cofactor_mode != key_cofactor_mode:
506		* - if ctx->k->cofactor == 1, the cofactor_mode flag is irrelevant, use
507		* ctx->k directly
508		* - if ctx->k->cofactor != 1, use a duplicate of ctx->k with the flag
509		* set to ctx->cofactor_mode
510		*/
511	3.02k	key_cofactor_mode = (EC_KEY_get_flags(pecdhctx->k) & EC_FLAG_COFACTOR_ECDH) ? 1 : 0;
512	3.02k	if (pecdhctx->cofactor_mode != -1
513	0	&& pecdhctx->cofactor_mode != key_cofactor_mode
514	0	&& has_cofactor) {
515	0	if ((privk = EC_KEY_dup(pecdhctx->k)) == NULL)
516	0	return 0;
517
518	0	if (pecdhctx->cofactor_mode == 1) {
519	0	EC_KEY_set_flags(privk, EC_FLAG_COFACTOR_ECDH);
520		#ifdef FIPS_MODULE
521		cofactor_approved = 1;
522		#endif
523	0	} else {
524	0	EC_KEY_clear_flags(privk, EC_FLAG_COFACTOR_ECDH);
525	0	}
526	3.02k	} else {
527	3.02k	privk = pecdhctx->k;
528		#ifdef FIPS_MODULE
529		cofactor_approved = key_cofactor_mode;
530		#endif
531	3.02k	}
532
533		#ifdef FIPS_MODULE
534		/*
535		* SP800-56A r3 Section 5.7.1.2 requires ECC Cofactor DH to be used.
536		* This applies to the 'B' and 'K' curves that have cofactors that are not 1.
537		*/
538		if (has_cofactor && !cofactor_approved) {
539		if (!OSSL_FIPS_IND_ON_UNAPPROVED(pecdhctx, OSSL_FIPS_IND_SETTABLE2,
540		pecdhctx->libctx, "ECDH", "Cofactor",
541		ossl_fips_config_ecdh_cofactor_check)) {
542		ERR_raise(ERR_LIB_PROV, PROV_R_COFACTOR_REQUIRED);
543		goto end;
544		}
545		}
546		#endif
547
548	3.02k	ppubkey = EC_KEY_get0_public_key(pecdhctx->peerk);
549
550	3.02k	retlen = ECDH_compute_key(secret, size, ppubkey, privk, NULL);
551
552	3.02k	if (retlen <= 0)
553	0	goto end;
554
555	3.02k	*psecretlen = retlen;
556	3.02k	ret = 1;
557
558	3.02k	end:
559	3.02k	if (privk != pecdhctx->k)
560	0	EC_KEY_free(privk);
561	3.02k	return ret;
562	3.02k	}
563
564		static ossl_inline int ecdh_X9_63_kdf_derive(void vpecdhctx, unsigned char secret,
565		size_t *psecretlen, size_t outlen)
566	0	{
567	0	PROV_ECDH_CTX pecdhctx = (PROV_ECDH_CTX )vpecdhctx;
568	0	unsigned char *stmp = NULL;
569	0	size_t stmplen;
570	0	int ret = 0;
571
572	0	if (secret == NULL) {
573	0	*psecretlen = pecdhctx->kdf_outlen;
574	0	return 1;
575	0	}
576
577	0	if (pecdhctx->kdf_outlen > outlen) {
578	0	ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
579	0	return 0;
580	0	}
581	0	if (!ecdh_plain_derive(vpecdhctx, NULL, &stmplen, 0))
582	0	return 0;
583	0	if ((stmp = OPENSSL_secure_malloc(stmplen)) == NULL)
584	0	return 0;
585	0	if (!ecdh_plain_derive(vpecdhctx, stmp, &stmplen, stmplen))
586	0	goto err;
587
588		/* Do KDF stuff */
589	0	if (!ossl_ecdh_kdf_X9_63(secret, pecdhctx->kdf_outlen,
590	0	stmp, stmplen,
591	0	pecdhctx->kdf_ukm,
592	0	pecdhctx->kdf_ukmlen,
593	0	pecdhctx->kdf_md,
594	0	pecdhctx->libctx, NULL))
595	0	goto err;
596	0	*psecretlen = pecdhctx->kdf_outlen;
597	0	ret = 1;
598
599	0	err:
600	0	OPENSSL_secure_clear_free(stmp, stmplen);
601	0	return ret;
602	0	}
603
604		static int ecdh_derive(void vpecdhctx, unsigned char secret,
605		size_t *psecretlen, size_t outlen)
606	8.57k	{
607	8.57k	PROV_ECDH_CTX pecdhctx = (PROV_ECDH_CTX )vpecdhctx;
608
609	8.57k	switch (pecdhctx->kdf_type) {
610	8.57k	case PROV_ECDH_KDF_NONE:
611	8.57k	return ecdh_plain_derive(vpecdhctx, secret, psecretlen, outlen);
612	0	case PROV_ECDH_KDF_X9_63:
613	0	return ecdh_X9_63_kdf_derive(vpecdhctx, secret, psecretlen, outlen);
614	0	default:
615	0	break;
616	8.57k	}
617	0	return 0;
618	8.57k	}
619
620		const OSSL_DISPATCH ossl_ecdh_keyexch_functions[] = {
621		{ OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))ecdh_newctx },
622		{ OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))ecdh_init },
623		{ OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))ecdh_derive },
624		{ OSSL_FUNC_KEYEXCH_SET_PEER, (void (*)(void))ecdh_set_peer },
625		{ OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))ecdh_freectx },
626		{ OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))ecdh_dupctx },
627		{ OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS, (void (*)(void))ecdh_set_ctx_params },
628		{ OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS,
629		(void (*)(void))ecdh_settable_ctx_params },
630		{ OSSL_FUNC_KEYEXCH_GET_CTX_PARAMS, (void (*)(void))ecdh_get_ctx_params },
631		{ OSSL_FUNC_KEYEXCH_GETTABLE_CTX_PARAMS,
632		(void (*)(void))ecdh_gettable_ctx_params },
633		OSSL_DISPATCH_END
634		};