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

Source
/*
 * Copyright 2019-2026 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
 */

/*
 * DH 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/core_dispatch.h>
#include <openssl/core_names.h>
#include <openssl/dh.h>
#include <openssl/err.h>
#include <openssl/proverr.h>
#include <openssl/params.h>
#include "prov/providercommon.h"
#include "prov/implementations.h"
#include "prov/provider_ctx.h"
#include "prov/securitycheck.h"
#include "crypto/dh.h"

static OSSL_FUNC_keyexch_newctx_fn dh_newctx;
static OSSL_FUNC_keyexch_init_fn dh_init;
static OSSL_FUNC_keyexch_set_peer_fn dh_set_peer;
static OSSL_FUNC_keyexch_derive_fn dh_derive;
static OSSL_FUNC_keyexch_freectx_fn dh_freectx;
static OSSL_FUNC_keyexch_dupctx_fn dh_dupctx;
static OSSL_FUNC_keyexch_set_ctx_params_fn dh_set_ctx_params;
static OSSL_FUNC_keyexch_settable_ctx_params_fn dh_settable_ctx_params;
static OSSL_FUNC_keyexch_get_ctx_params_fn dh_get_ctx_params;
static OSSL_FUNC_keyexch_gettable_ctx_params_fn dh_gettable_ctx_params;

/*
 * This type is only really used to handle some legacy related functionality.
 * If you need to use other KDF's (such as SSKDF) just use PROV_DH_KDF_NONE
 * here and then create and run a KDF after the key is derived.
 * Note that X942 has 2 variants of key derivation:
 *   (1) DH_KDF_X9_42_ASN1 - which contains an ANS1 encoded object that has
 *   the counter embedded in it.
 *   (2) DH_KDF_X941_CONCAT - which is the same as ECDH_X963_KDF (which can be
 *       done by creating a "X963KDF".
 */
enum kdf_type {
    PROV_DH_KDF_NONE = 0,
    PROV_DH_KDF_X9_42_ASN1
};

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

typedef struct {
    OSSL_LIB_CTX *libctx;
    DH *dh;
    DH *dhpeer;
    unsigned int pad : 1;

    /* DH KDF */
    /* KDF (if any) to use for DH */
    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;
    char *kdf_cekalg;
    OSSL_FIPS_IND_DECLARE
} PROV_DH_CTX;

static void *dh_newctx(void *provctx)
{
    PROV_DH_CTX *pdhctx;

    if (!ossl_prov_is_running())
        return NULL;

    pdhctx = OPENSSL_zalloc(sizeof(PROV_DH_CTX));
    if (pdhctx == NULL)
        return NULL;
    OSSL_FIPS_IND_INIT(pdhctx)
    pdhctx->libctx = PROV_LIBCTX_OF(provctx);
    pdhctx->kdf_type = PROV_DH_KDF_NONE;
    return pdhctx;
}

#ifdef FIPS_MODULE
static int dh_check_key(PROV_DH_CTX *ctx)
{
    int key_approved = ossl_dh_check_key(ctx->dh);

    if (!key_approved) {
        if (!OSSL_FIPS_IND_ON_UNAPPROVED(ctx, OSSL_FIPS_IND_SETTABLE0,
                ctx->libctx, "DH Init", "DH Key",
                ossl_fips_config_securitycheck_enabled)) {
            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
            return 0;
        }
    }
    return 1;
}

static int digest_check(PROV_DH_CTX *ctx, const EVP_MD *md)
{
    return ossl_fips_ind_digest_exch_check(OSSL_FIPS_IND_GET(ctx),
        OSSL_FIPS_IND_SETTABLE1, ctx->libctx,
        md, "DH Set Ctx");
}
#endif

static int dh_init(void *vpdhctx, void *vdh, const OSSL_PARAM params[])
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;

    if (!ossl_prov_is_running()
        || pdhctx == NULL
        || vdh == NULL
        || !DH_up_ref(vdh))
        return 0;
    DH_free(pdhctx->dh);
    pdhctx->dh = vdh;
    pdhctx->kdf_type = PROV_DH_KDF_NONE;

    OSSL_FIPS_IND_SET_APPROVED(pdhctx)
    if (!dh_set_ctx_params(pdhctx, params))
        return 0;
#ifdef FIPS_MODULE
    if (!dh_check_key(pdhctx))
        return 0;
#endif
    return 1;
}

/* The 2 parties must share the same domain parameters */
static int dh_match_params(DH *priv, DH *peer)
{
    int ret;
    int ignore_q = 1;
    FFC_PARAMS *dhparams_priv = ossl_dh_get0_params(priv);
    FFC_PARAMS *dhparams_peer = ossl_dh_get0_params(peer);

    if (dhparams_priv != NULL && dhparams_priv->q != NULL)
        ignore_q = 0;
    ret = dhparams_priv != NULL
        && dhparams_peer != NULL
        && ossl_ffc_params_cmp(dhparams_priv, dhparams_peer, ignore_q);
    if (!ret)
        ERR_raise(ERR_LIB_PROV, PROV_R_MISMATCHING_DOMAIN_PARAMETERS);
    return ret;
}

static int dh_set_peer(void *vpdhctx, void *vdh)
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;

    if (!ossl_prov_is_running()
        || pdhctx == NULL
        || vdh == NULL
        || !dh_match_params(vdh, pdhctx->dh)
        || !DH_up_ref(vdh))
        return 0;
    DH_free(pdhctx->dhpeer);
    pdhctx->dhpeer = vdh;
    return 1;
}

static int dh_plain_derive(void *vpdhctx,
    unsigned char *secret, size_t *secretlen,
    size_t outlen, unsigned int pad)
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
    int ret;
    size_t dhsize;
    const BIGNUM *pub_key = NULL;

    if (pdhctx->dh == NULL || pdhctx->dhpeer == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
        return 0;
    }

    dhsize = (size_t)DH_size(pdhctx->dh);
    if (secret == NULL) {
        *secretlen = dhsize;
        return 1;
    }
    if (outlen < dhsize) {
        ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
        return 0;
    }

    DH_get0_key(pdhctx->dhpeer, &pub_key, NULL);
    if (pad)
        ret = DH_compute_key_padded(secret, pub_key, pdhctx->dh);
    else
        ret = DH_compute_key(secret, pub_key, pdhctx->dh);
    if (ret <= 0)
        return 0;

    *secretlen = ret;
    return 1;
}

static int dh_X9_42_kdf_derive(void *vpdhctx, unsigned char *secret,
    size_t *secretlen, size_t outlen)
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
    unsigned char *stmp = NULL;
    size_t stmplen;
    int ret = 0;

    if (secret == NULL) {
        *secretlen = pdhctx->kdf_outlen;
        return 1;
    }

    if (pdhctx->kdf_outlen > outlen) {
        ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
        return 0;
    }
    if (!dh_plain_derive(pdhctx, NULL, &stmplen, 0, 1))
        return 0;
    if ((stmp = OPENSSL_secure_malloc(stmplen)) == NULL)
        return 0;
    if (!dh_plain_derive(pdhctx, stmp, &stmplen, stmplen, 1))
        goto err;

    /* Do KDF stuff */
    if (pdhctx->kdf_type == PROV_DH_KDF_X9_42_ASN1) {
        if (!ossl_dh_kdf_X9_42_asn1(secret, pdhctx->kdf_outlen,
                stmp, stmplen,
                pdhctx->kdf_cekalg,
                pdhctx->kdf_ukm,
                pdhctx->kdf_ukmlen,
                pdhctx->kdf_md,
                pdhctx->libctx, NULL))
            goto err;
    }
    *secretlen = pdhctx->kdf_outlen;
    ret = 1;
err:
    OPENSSL_secure_clear_free(stmp, stmplen);
    return ret;
}

static int dh_derive(void *vpdhctx, unsigned char *secret,
    size_t *psecretlen, size_t outlen)
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;

    if (!ossl_prov_is_running())
        return 0;

    switch (pdhctx->kdf_type) {
    case PROV_DH_KDF_NONE:
        return dh_plain_derive(pdhctx, secret, psecretlen, outlen,
            pdhctx->pad);
    case PROV_DH_KDF_X9_42_ASN1:
        return dh_X9_42_kdf_derive(pdhctx, secret, psecretlen, outlen);
    default:
        break;
    }
    return 0;
}

static void dh_freectx(void *vpdhctx)
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;

    OPENSSL_free(pdhctx->kdf_cekalg);
    DH_free(pdhctx->dh);
    DH_free(pdhctx->dhpeer);
    EVP_MD_free(pdhctx->kdf_md);
    OPENSSL_clear_free(pdhctx->kdf_ukm, pdhctx->kdf_ukmlen);

    OPENSSL_free(pdhctx);
}

static void *dh_dupctx(void *vpdhctx)
{
    PROV_DH_CTX *srcctx = (PROV_DH_CTX *)vpdhctx;
    PROV_DH_CTX *dstctx;

    if (!ossl_prov_is_running())
        return NULL;

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

    *dstctx = *srcctx;
    dstctx->dh = NULL;
    dstctx->dhpeer = NULL;
    dstctx->kdf_md = NULL;
    dstctx->kdf_ukm = NULL;
    dstctx->kdf_cekalg = NULL;

    if (srcctx->dh != NULL && !DH_up_ref(srcctx->dh))
        goto err;
    else
        dstctx->dh = srcctx->dh;

    if (srcctx->dhpeer != NULL && !DH_up_ref(srcctx->dhpeer))
        goto err;
    else
        dstctx->dhpeer = srcctx->dhpeer;

    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;
    }

    if (srcctx->kdf_cekalg != NULL) {
        dstctx->kdf_cekalg = OPENSSL_strdup(srcctx->kdf_cekalg);
        if (dstctx->kdf_cekalg == NULL)
            goto err;
    }

    return dstctx;
err:
    dh_freectx(dstctx);
    return NULL;
}

static int dh_set_ctx_params(void *vpdhctx, const OSSL_PARAM params[])
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
    const OSSL_PARAM *p;
    unsigned int pad;
    char name[80] = { '\0' }; /* should be big enough */
    char *str = NULL;

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

    if (!OSSL_FIPS_IND_SET_CTX_PARAM(pdhctx, OSSL_FIPS_IND_SETTABLE0, params,
            OSSL_EXCHANGE_PARAM_FIPS_KEY_CHECK))
        return 0;
    if (!OSSL_FIPS_IND_SET_CTX_PARAM(pdhctx, OSSL_FIPS_IND_SETTABLE1, params,
            OSSL_EXCHANGE_PARAM_FIPS_DIGEST_CHECK))
        return 0;

    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')
            pdhctx->kdf_type = PROV_DH_KDF_NONE;
        else if (strcmp(name, OSSL_KDF_NAME_X942KDF_ASN1) == 0)
            pdhctx->kdf_type = PROV_DH_KDF_X9_42_ASN1;
        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(pdhctx->kdf_md);
        pdhctx->kdf_md = EVP_MD_fetch(pdhctx->libctx, name, mdprops);
        if (pdhctx->kdf_md == NULL)
            return 0;
        /* XOF digests are not allowed */
        if (EVP_MD_xof(pdhctx->kdf_md)) {
            ERR_raise(ERR_LIB_PROV, PROV_R_XOF_DIGESTS_NOT_ALLOWED);
            return 0;
        }
#ifdef FIPS_MODULE
        if (!digest_check(pdhctx, pdhctx->kdf_md)) {
            EVP_MD_free(pdhctx->kdf_md);
            pdhctx->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;
        pdhctx->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;

        OPENSSL_free(pdhctx->kdf_ukm);
        pdhctx->kdf_ukm = NULL;
        pdhctx->kdf_ukmlen = 0;
        /* ukm is an optional field so it can be NULL */
        if (p->data != NULL && p->data_size != 0) {
            if (!OSSL_PARAM_get_octet_string(p, &tmp_ukm, 0, &tmp_ukmlen))
                return 0;
            pdhctx->kdf_ukm = tmp_ukm;
            pdhctx->kdf_ukmlen = tmp_ukmlen;
        }
    }

    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_PAD);
    if (p != NULL) {
        if (!OSSL_PARAM_get_uint(p, &pad))
            return 0;
        pdhctx->pad = pad ? 1 : 0;
    }

    p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_CEK_ALG);
    if (p != NULL) {
        str = name;

        OPENSSL_free(pdhctx->kdf_cekalg);
        pdhctx->kdf_cekalg = NULL;
        if (p->data != NULL && p->data_size != 0) {
            if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
                return 0;
            pdhctx->kdf_cekalg = OPENSSL_strdup(name);
            if (pdhctx->kdf_cekalg == NULL)
                return 0;
        }
    }
    return 1;
}

static const OSSL_PARAM known_settable_ctx_params[] = {
    OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_PAD, 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_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, 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_PARAM_END
};

static const OSSL_PARAM *dh_settable_ctx_params(ossl_unused void *vpdhctx,
    ossl_unused void *provctx)
{
    return known_settable_ctx_params;
}

static const OSSL_PARAM known_gettable_ctx_params[] = {
    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_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, NULL, 0),
    OSSL_FIPS_IND_GETTABLE_CTX_PARAM()
        OSSL_PARAM_END
};

static const OSSL_PARAM *dh_gettable_ctx_params(ossl_unused void *vpdhctx,
    ossl_unused void *provctx)
{
    return known_gettable_ctx_params;
}

static int dh_get_ctx_params(void *vpdhctx, OSSL_PARAM params[])
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
    OSSL_PARAM *p;

    if (pdhctx == NULL)
        return 0;

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

        switch (pdhctx->kdf_type) {
        case PROV_DH_KDF_NONE:
            kdf_type = "";
            break;
        case PROV_DH_KDF_X9_42_ASN1:
            kdf_type = OSSL_KDF_NAME_X942KDF_ASN1;
            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, pdhctx->kdf_md == NULL ? "" : EVP_MD_get0_name(pdhctx->kdf_md))) {
        return 0;
    }

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

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

    p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_CEK_ALG);
    if (p != NULL
        && !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_cekalg == NULL ? "" : pdhctx->kdf_cekalg))
        return 0;
    if (!OSSL_FIPS_IND_GET_CTX_PARAM(pdhctx, params))
        return 0;
    return 1;
}

const OSSL_DISPATCH ossl_dh_keyexch_functions[] = {
    { OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))dh_newctx },
    { OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))dh_init },
    { OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))dh_derive },
    { OSSL_FUNC_KEYEXCH_SET_PEER, (void (*)(void))dh_set_peer },
    { OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))dh_freectx },
    { OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))dh_dupctx },
    { OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS, (void (*)(void))dh_set_ctx_params },
    { OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS,
        (void (*)(void))dh_settable_ctx_params },
    { OSSL_FUNC_KEYEXCH_GET_CTX_PARAMS, (void (*)(void))dh_get_ctx_params },
    { OSSL_FUNC_KEYEXCH_GETTABLE_CTX_PARAMS,
        (void (*)(void))dh_gettable_ctx_params },
    OSSL_DISPATCH_END
};

Coverage Report

Created: 2026-07-23 06:28

Line	Count	Source
1		/*
2		* Copyright 2019-2026 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		* DH 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/core_dispatch.h>
19		#include <openssl/core_names.h>
20		#include <openssl/dh.h>
21		#include <openssl/err.h>
22		#include <openssl/proverr.h>
23		#include <openssl/params.h>
24		#include "prov/providercommon.h"
25		#include "prov/implementations.h"
26		#include "prov/provider_ctx.h"
27		#include "prov/securitycheck.h"
28		#include "crypto/dh.h"
29
30		static OSSL_FUNC_keyexch_newctx_fn dh_newctx;
31		static OSSL_FUNC_keyexch_init_fn dh_init;
32		static OSSL_FUNC_keyexch_set_peer_fn dh_set_peer;
33		static OSSL_FUNC_keyexch_derive_fn dh_derive;
34		static OSSL_FUNC_keyexch_freectx_fn dh_freectx;
35		static OSSL_FUNC_keyexch_dupctx_fn dh_dupctx;
36		static OSSL_FUNC_keyexch_set_ctx_params_fn dh_set_ctx_params;
37		static OSSL_FUNC_keyexch_settable_ctx_params_fn dh_settable_ctx_params;
38		static OSSL_FUNC_keyexch_get_ctx_params_fn dh_get_ctx_params;
39		static OSSL_FUNC_keyexch_gettable_ctx_params_fn dh_gettable_ctx_params;
40
41		/*
42		* This type is only really used to handle some legacy related functionality.
43		* If you need to use other KDF's (such as SSKDF) just use PROV_DH_KDF_NONE
44		* here and then create and run a KDF after the key is derived.
45		* Note that X942 has 2 variants of key derivation:
46		* (1) DH_KDF_X9_42_ASN1 - which contains an ANS1 encoded object that has
47		* the counter embedded in it.
48		* (2) DH_KDF_X941_CONCAT - which is the same as ECDH_X963_KDF (which can be
49		* done by creating a "X963KDF".
50		*/
51		enum kdf_type {
52		PROV_DH_KDF_NONE = 0,
53		PROV_DH_KDF_X9_42_ASN1
54		};
55
56		/*
57		* What's passed as an actual key is defined by the KEYMGMT interface.
58		* We happen to know that our KEYMGMT simply passes DH structures, so
59		* we use that here too.
60		*/
61
62		typedef struct {
63		OSSL_LIB_CTX *libctx;
64		DH *dh;
65		DH *dhpeer;
66		unsigned int pad : 1;
67
68		/* DH KDF */
69		/* KDF (if any) to use for DH */
70		enum kdf_type kdf_type;
71		/* Message digest to use for key derivation */
72		EVP_MD *kdf_md;
73		/* User key material */
74		unsigned char *kdf_ukm;
75		size_t kdf_ukmlen;
76		/* KDF output length */
77		size_t kdf_outlen;
78		char *kdf_cekalg;
79		OSSL_FIPS_IND_DECLARE
80		} PROV_DH_CTX;
81
82		static void dh_newctx(void provctx)
83	4.64k	{
84	4.64k	PROV_DH_CTX *pdhctx;
85
86	4.64k	if (!ossl_prov_is_running())
87	0	return NULL;
88
89	4.64k	pdhctx = OPENSSL_zalloc(sizeof(PROV_DH_CTX));
90	4.64k	if (pdhctx == NULL)
91	0	return NULL;
92	4.64k	OSSL_FIPS_IND_INIT(pdhctx)
93	4.64k	pdhctx->libctx = PROV_LIBCTX_OF(provctx);
94	4.64k	pdhctx->kdf_type = PROV_DH_KDF_NONE;
95	4.64k	return pdhctx;
96	4.64k	}
97
98		#ifdef FIPS_MODULE
99		static int dh_check_key(PROV_DH_CTX *ctx)
100		{
101		int key_approved = ossl_dh_check_key(ctx->dh);
102
103		if (!key_approved) {
104		if (!OSSL_FIPS_IND_ON_UNAPPROVED(ctx, OSSL_FIPS_IND_SETTABLE0,
105		ctx->libctx, "DH Init", "DH Key",
106		ossl_fips_config_securitycheck_enabled)) {
107		ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
108		return 0;
109		}
110		}
111		return 1;
112		}
113
114		static int digest_check(PROV_DH_CTX ctx, const EVP_MD md)
115		{
116		return ossl_fips_ind_digest_exch_check(OSSL_FIPS_IND_GET(ctx),
117		OSSL_FIPS_IND_SETTABLE1, ctx->libctx,
118		md, "DH Set Ctx");
119		}
120		#endif
121
122		static int dh_init(void vpdhctx, void vdh, const OSSL_PARAM params[])
123	2.79k	{
124	2.79k	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
125
126	2.79k	if (!ossl_prov_is_running()
127	2.79k	\|\| pdhctx == NULL
128	2.79k	\|\| vdh == NULL
129	2.79k	\|\| !DH_up_ref(vdh))
130	0	return 0;
131	2.79k	DH_free(pdhctx->dh);
132	2.79k	pdhctx->dh = vdh;
133	2.79k	pdhctx->kdf_type = PROV_DH_KDF_NONE;
134
135	2.79k	OSSL_FIPS_IND_SET_APPROVED(pdhctx)
136	2.79k	if (!dh_set_ctx_params(pdhctx, params))
137	0	return 0;
138		#ifdef FIPS_MODULE
139		if (!dh_check_key(pdhctx))
140		return 0;
141		#endif
142	2.79k	return 1;
143	2.79k	}
144
145		/* The 2 parties must share the same domain parameters */
146		static int dh_match_params(DH priv, DH peer)
147	3.46k	{
148	3.46k	int ret;
149	3.46k	int ignore_q = 1;
150	3.46k	FFC_PARAMS *dhparams_priv = ossl_dh_get0_params(priv);
151	3.46k	FFC_PARAMS *dhparams_peer = ossl_dh_get0_params(peer);
152
153	3.46k	if (dhparams_priv != NULL && dhparams_priv->q != NULL)
154	480	ignore_q = 0;
155	3.46k	ret = dhparams_priv != NULL
156	3.46k	&& dhparams_peer != NULL
157	3.46k	&& ossl_ffc_params_cmp(dhparams_priv, dhparams_peer, ignore_q);
158	3.46k	if (!ret)
159	3.46k	ERR_raise(ERR_LIB_PROV, PROV_R_MISMATCHING_DOMAIN_PARAMETERS);
160	3.46k	return ret;
161	3.46k	}
162
163		static int dh_set_peer(void vpdhctx, void vdh)
164	4.34k	{
165	4.34k	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
166
167	4.34k	if (!ossl_prov_is_running()
168	4.34k	\|\| pdhctx == NULL
169	4.34k	\|\| vdh == NULL
170	4.34k	\|\| !dh_match_params(vdh, pdhctx->dh)
171	4.34k	\|\| !DH_up_ref(vdh))
172	0	return 0;
173	4.34k	DH_free(pdhctx->dhpeer);
174	4.34k	pdhctx->dhpeer = vdh;
175	4.34k	return 1;
176	4.34k	}
177
178		static int dh_plain_derive(void *vpdhctx,
179		unsigned char secret, size_t secretlen,
180		size_t outlen, unsigned int pad)
181	8.68k	{
182	8.68k	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
183	8.68k	int ret;
184	8.68k	size_t dhsize;
185	8.68k	const BIGNUM *pub_key = NULL;
186
187	8.68k	if (pdhctx->dh == NULL \|\| pdhctx->dhpeer == NULL) {
188	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
189	0	return 0;
190	0	}
191
192	8.68k	dhsize = (size_t)DH_size(pdhctx->dh);
193	8.68k	if (secret == NULL) {
194	4.34k	*secretlen = dhsize;
195	4.34k	return 1;
196	4.34k	}
197	4.34k	if (outlen < dhsize) {
198	0	ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
199	0	return 0;
200	0	}
201
202	4.34k	DH_get0_key(pdhctx->dhpeer, &pub_key, NULL);
203	4.34k	if (pad)
204	96	ret = DH_compute_key_padded(secret, pub_key, pdhctx->dh);
205	4.24k	else
206	4.24k	ret = DH_compute_key(secret, pub_key, pdhctx->dh);
207	4.34k	if (ret <= 0)
208	0	return 0;
209
210	4.34k	*secretlen = ret;
211	4.34k	return 1;
212	4.34k	}
213
214		static int dh_X9_42_kdf_derive(void vpdhctx, unsigned char secret,
215		size_t *secretlen, size_t outlen)
216	0	{
217	0	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
218	0	unsigned char *stmp = NULL;
219	0	size_t stmplen;
220	0	int ret = 0;
221
222	0	if (secret == NULL) {
223	0	*secretlen = pdhctx->kdf_outlen;
224	0	return 1;
225	0	}
226
227	0	if (pdhctx->kdf_outlen > outlen) {
228	0	ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
229	0	return 0;
230	0	}
231	0	if (!dh_plain_derive(pdhctx, NULL, &stmplen, 0, 1))
232	0	return 0;
233	0	if ((stmp = OPENSSL_secure_malloc(stmplen)) == NULL)
234	0	return 0;
235	0	if (!dh_plain_derive(pdhctx, stmp, &stmplen, stmplen, 1))
236	0	goto err;
237
238		/* Do KDF stuff */
239	0	if (pdhctx->kdf_type == PROV_DH_KDF_X9_42_ASN1) {
240	0	if (!ossl_dh_kdf_X9_42_asn1(secret, pdhctx->kdf_outlen,
241	0	stmp, stmplen,
242	0	pdhctx->kdf_cekalg,
243	0	pdhctx->kdf_ukm,
244	0	pdhctx->kdf_ukmlen,
245	0	pdhctx->kdf_md,
246	0	pdhctx->libctx, NULL))
247	0	goto err;
248	0	}
249	0	*secretlen = pdhctx->kdf_outlen;
250	0	ret = 1;
251	0	err:
252	0	OPENSSL_secure_clear_free(stmp, stmplen);
253	0	return ret;
254	0	}
255
256		static int dh_derive(void vpdhctx, unsigned char secret,
257		size_t *psecretlen, size_t outlen)
258	8.68k	{
259	8.68k	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
260
261	8.68k	if (!ossl_prov_is_running())
262	0	return 0;
263
264	8.68k	switch (pdhctx->kdf_type) {
265	8.68k	case PROV_DH_KDF_NONE:
266	8.68k	return dh_plain_derive(pdhctx, secret, psecretlen, outlen,
267	8.68k	pdhctx->pad);
268	0	case PROV_DH_KDF_X9_42_ASN1:
269	0	return dh_X9_42_kdf_derive(pdhctx, secret, psecretlen, outlen);
270	0	default:
271	0	break;
272	8.68k	}
273	0	return 0;
274	8.68k	}
275
276		static void dh_freectx(void *vpdhctx)
277	4.64k	{
278	4.64k	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
279
280	4.64k	OPENSSL_free(pdhctx->kdf_cekalg);
281	4.64k	DH_free(pdhctx->dh);
282	4.64k	DH_free(pdhctx->dhpeer);
283	4.64k	EVP_MD_free(pdhctx->kdf_md);
284	4.64k	OPENSSL_clear_free(pdhctx->kdf_ukm, pdhctx->kdf_ukmlen);
285
286	4.64k	OPENSSL_free(pdhctx);
287	4.64k	}
288
289		static void dh_dupctx(void vpdhctx)
290	0	{
291	0	PROV_DH_CTX srcctx = (PROV_DH_CTX )vpdhctx;
292	0	PROV_DH_CTX *dstctx;
293
294	0	if (!ossl_prov_is_running())
295	0	return NULL;
296
297	0	dstctx = OPENSSL_zalloc(sizeof(*srcctx));
298	0	if (dstctx == NULL)
299	0	return NULL;
300
301	0	dstctx = srcctx;
302	0	dstctx->dh = NULL;
303	0	dstctx->dhpeer = NULL;
304	0	dstctx->kdf_md = NULL;
305	0	dstctx->kdf_ukm = NULL;
306	0	dstctx->kdf_cekalg = NULL;
307
308	0	if (srcctx->dh != NULL && !DH_up_ref(srcctx->dh))
309	0	goto err;
310	0	else
311	0	dstctx->dh = srcctx->dh;
312
313	0	if (srcctx->dhpeer != NULL && !DH_up_ref(srcctx->dhpeer))
314	0	goto err;
315	0	else
316	0	dstctx->dhpeer = srcctx->dhpeer;
317
318	0	if (srcctx->kdf_md != NULL && !EVP_MD_up_ref(srcctx->kdf_md))
319	0	goto err;
320	0	else
321	0	dstctx->kdf_md = srcctx->kdf_md;
322
323		/* Duplicate UKM data if present */
324	0	if (srcctx->kdf_ukm != NULL && srcctx->kdf_ukmlen > 0) {
325	0	dstctx->kdf_ukm = OPENSSL_memdup(srcctx->kdf_ukm,
326	0	srcctx->kdf_ukmlen);
327	0	if (dstctx->kdf_ukm == NULL)
328	0	goto err;
329	0	}
330
331	0	if (srcctx->kdf_cekalg != NULL) {
332	0	dstctx->kdf_cekalg = OPENSSL_strdup(srcctx->kdf_cekalg);
333	0	if (dstctx->kdf_cekalg == NULL)
334	0	goto err;
335	0	}
336
337	0	return dstctx;
338	0	err:
339	0	dh_freectx(dstctx);
340	0	return NULL;
341	0	}
342
343		static int dh_set_ctx_params(void *vpdhctx, const OSSL_PARAM params[])
344	699	{
345	699	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
346	699	const OSSL_PARAM *p;
347	699	unsigned int pad;
348	699	char name[80] = { '\0' }; /* should be big enough */
349	699	char *str = NULL;
350
351	699	if (pdhctx == NULL)
352	0	return 0;
353	699	if (ossl_param_is_empty(params))
354	699	return 1;
355
356	0	if (!OSSL_FIPS_IND_SET_CTX_PARAM(pdhctx, OSSL_FIPS_IND_SETTABLE0, params,
357	0	OSSL_EXCHANGE_PARAM_FIPS_KEY_CHECK))
358	0	return 0;
359	0	if (!OSSL_FIPS_IND_SET_CTX_PARAM(pdhctx, OSSL_FIPS_IND_SETTABLE1, params,
360	0	OSSL_EXCHANGE_PARAM_FIPS_DIGEST_CHECK))
361	0	return 0;
362
363	0	p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
364	0	if (p != NULL) {
365	0	str = name;
366	0	if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
367	0	return 0;
368
369	0	if (name[0] == '\0')
370	0	pdhctx->kdf_type = PROV_DH_KDF_NONE;
371	0	else if (strcmp(name, OSSL_KDF_NAME_X942KDF_ASN1) == 0)
372	0	pdhctx->kdf_type = PROV_DH_KDF_X9_42_ASN1;
373	0	else
374	0	return 0;
375	0	}
376	0	p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
377	0	if (p != NULL) {
378	0	char mdprops[80] = { '\0' }; /* should be big enough */
379
380	0	str = name;
381	0	if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
382	0	return 0;
383
384	0	str = mdprops;
385	0	p = OSSL_PARAM_locate_const(params,
386	0	OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS);
387
388	0	if (p != NULL) {
389	0	if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(mdprops)))
390	0	return 0;
391	0	}
392
393	0	EVP_MD_free(pdhctx->kdf_md);
394	0	pdhctx->kdf_md = EVP_MD_fetch(pdhctx->libctx, name, mdprops);
395	0	if (pdhctx->kdf_md == NULL)
396	0	return 0;
397		/* XOF digests are not allowed */
398	0	if (EVP_MD_xof(pdhctx->kdf_md)) {
399	0	ERR_raise(ERR_LIB_PROV, PROV_R_XOF_DIGESTS_NOT_ALLOWED);
400	0	return 0;
401	0	}
402		#ifdef FIPS_MODULE
403		if (!digest_check(pdhctx, pdhctx->kdf_md)) {
404		EVP_MD_free(pdhctx->kdf_md);
405		pdhctx->kdf_md = NULL;
406		return 0;
407		}
408		#endif
409	0	}
410
411	0	p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
412	0	if (p != NULL) {
413	0	size_t outlen;
414
415	0	if (!OSSL_PARAM_get_size_t(p, &outlen))
416	0	return 0;
417	0	pdhctx->kdf_outlen = outlen;
418	0	}
419
420	0	p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
421	0	if (p != NULL) {
422	0	void *tmp_ukm = NULL;
423	0	size_t tmp_ukmlen;
424
425	0	OPENSSL_free(pdhctx->kdf_ukm);
426	0	pdhctx->kdf_ukm = NULL;
427	0	pdhctx->kdf_ukmlen = 0;
428		/* ukm is an optional field so it can be NULL */
429	0	if (p->data != NULL && p->data_size != 0) {
430	0	if (!OSSL_PARAM_get_octet_string(p, &tmp_ukm, 0, &tmp_ukmlen))
431	0	return 0;
432	0	pdhctx->kdf_ukm = tmp_ukm;
433	0	pdhctx->kdf_ukmlen = tmp_ukmlen;
434	0	}
435	0	}
436
437	0	p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_PAD);
438	0	if (p != NULL) {
439	0	if (!OSSL_PARAM_get_uint(p, &pad))
440	0	return 0;
441	0	pdhctx->pad = pad ? 1 : 0;
442	0	}
443
444	0	p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_CEK_ALG);
445	0	if (p != NULL) {
446	0	str = name;
447
448	0	OPENSSL_free(pdhctx->kdf_cekalg);
449	0	pdhctx->kdf_cekalg = NULL;
450	0	if (p->data != NULL && p->data_size != 0) {
451	0	if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
452	0	return 0;
453	0	pdhctx->kdf_cekalg = OPENSSL_strdup(name);
454	0	if (pdhctx->kdf_cekalg == NULL)
455	0	return 0;
456	0	}
457	0	}
458	0	return 1;
459	0	}
460
461		static const OSSL_PARAM known_settable_ctx_params[] = {
462		OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_PAD, NULL),
463		OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
464		OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
465		OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS, NULL, 0),
466		OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
467		OSSL_PARAM_octet_string(OSSL_EXCHANGE_PARAM_KDF_UKM, NULL, 0),
468		OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, NULL, 0),
469		OSSL_FIPS_IND_SETTABLE_CTX_PARAM(OSSL_EXCHANGE_PARAM_FIPS_KEY_CHECK)
470		OSSL_FIPS_IND_SETTABLE_CTX_PARAM(OSSL_EXCHANGE_PARAM_FIPS_DIGEST_CHECK)
471		OSSL_PARAM_END
472		};
473
474		static const OSSL_PARAM dh_settable_ctx_params(ossl_unused void vpdhctx,
475		ossl_unused void *provctx)
476	112	{
477	112	return known_settable_ctx_params;
478	112	}
479
480		static const OSSL_PARAM known_gettable_ctx_params[] = {
481		OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
482		OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
483		OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
484		OSSL_PARAM_DEFN(OSSL_EXCHANGE_PARAM_KDF_UKM, OSSL_PARAM_OCTET_PTR,
485		NULL, 0),
486		OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, NULL, 0),
487		OSSL_FIPS_IND_GETTABLE_CTX_PARAM()
488		OSSL_PARAM_END
489		};
490
491		static const OSSL_PARAM dh_gettable_ctx_params(ossl_unused void vpdhctx,
492		ossl_unused void *provctx)
493	0	{
494	0	return known_gettable_ctx_params;
495	0	}
496
497		static int dh_get_ctx_params(void *vpdhctx, OSSL_PARAM params[])
498	0	{
499	0	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
500	0	OSSL_PARAM *p;
501
502	0	if (pdhctx == NULL)
503	0	return 0;
504
505	0	p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
506	0	if (p != NULL) {
507	0	const char *kdf_type = NULL;
508
509	0	switch (pdhctx->kdf_type) {
510	0	case PROV_DH_KDF_NONE:
511	0	kdf_type = "";
512	0	break;
513	0	case PROV_DH_KDF_X9_42_ASN1:
514	0	kdf_type = OSSL_KDF_NAME_X942KDF_ASN1;
515	0	break;
516	0	default:
517	0	return 0;
518	0	}
519
520	0	if (!OSSL_PARAM_set_utf8_string(p, kdf_type))
521	0	return 0;
522	0	}
523
524	0	p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
525	0	if (p != NULL
526	0	&& !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_md == NULL ? "" : EVP_MD_get0_name(pdhctx->kdf_md))) {
527	0	return 0;
528	0	}
529
530	0	p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
531	0	if (p != NULL && !OSSL_PARAM_set_size_t(p, pdhctx->kdf_outlen))
532	0	return 0;
533
534	0	p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
535	0	if (p != NULL
536	0	&& !OSSL_PARAM_set_octet_ptr(p, pdhctx->kdf_ukm, pdhctx->kdf_ukmlen))
537	0	return 0;
538
539	0	p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_CEK_ALG);
540	0	if (p != NULL
541	0	&& !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_cekalg == NULL ? "" : pdhctx->kdf_cekalg))
542	0	return 0;
543	0	if (!OSSL_FIPS_IND_GET_CTX_PARAM(pdhctx, params))
544	0	return 0;
545	0	return 1;
546	0	}
547
548		const OSSL_DISPATCH ossl_dh_keyexch_functions[] = {
549		{ OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))dh_newctx },
550		{ OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))dh_init },
551		{ OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))dh_derive },
552		{ OSSL_FUNC_KEYEXCH_SET_PEER, (void (*)(void))dh_set_peer },
553		{ OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))dh_freectx },
554		{ OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))dh_dupctx },
555		{ OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS, (void (*)(void))dh_set_ctx_params },
556		{ OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS,
557		(void (*)(void))dh_settable_ctx_params },
558		{ OSSL_FUNC_KEYEXCH_GET_CTX_PARAMS, (void (*)(void))dh_get_ctx_params },
559		{ OSSL_FUNC_KEYEXCH_GETTABLE_CTX_PARAMS,
560		(void (*)(void))dh_gettable_ctx_params },
561		OSSL_DISPATCH_END
562		};