[thirdparty/openssl.git] / crypto / dh / dh_key.c

/*
 * Copyright 1995-2020 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
 */

#include <stdio.h>
#include "internal/cryptlib.h"
#include "dh_local.h"
#include "crypto/bn.h"
#include "crypto/dh.h"

static int generate_key(DH *dh);
static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
                         const BIGNUM *a, const BIGNUM *p,
                         const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
static int dh_init(DH *dh);
static int dh_finish(DH *dh);

static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
{
    BN_CTX *ctx = NULL;
    BN_MONT_CTX *mont = NULL;
    BIGNUM *tmp;
    int ret = -1;
#ifndef FIPS_MODE
    int check_result;
#endif

    if (BN_num_bits(dh->params.p) > OPENSSL_DH_MAX_MODULUS_BITS) {
        DHerr(0, DH_R_MODULUS_TOO_LARGE);
        goto err;
    }

    if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS) {
        DHerr(0, DH_R_MODULUS_TOO_SMALL);
        return 0;
    }

    ctx = BN_CTX_new_ex(dh->libctx);
    if (ctx == NULL)
        goto err;
    BN_CTX_start(ctx);
    tmp = BN_CTX_get(ctx);
    if (tmp == NULL)
        goto err;

    if (dh->priv_key == NULL) {
        DHerr(0, DH_R_NO_PRIVATE_VALUE);
        goto err;
    }

    if (dh->flags & DH_FLAG_CACHE_MONT_P) {
        mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
                                      dh->lock, dh->params.p, ctx);
        BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME);
        if (!mont)
            goto err;
    }
/* TODO(3.0) : Solve in a PR related to Key validation for DH */
#ifndef FIPS_MODE
    if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result) {
        DHerr(0, DH_R_INVALID_PUBKEY);
        goto err;
    }
#endif
    if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key, dh->params.p, ctx,
                              mont)) {
        DHerr(0, ERR_R_BN_LIB);
        goto err;
    }

    ret = BN_bn2bin(tmp, key);
 err:
    BN_CTX_end(ctx);
    BN_CTX_free(ctx);
    return ret;
}

int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
{
#ifdef FIPS_MODE
    return compute_key(key, pub_key, dh);
#else
    return dh->meth->compute_key(key, pub_key, dh);
#endif
}

int DH_compute_key_padded(unsigned char *key, const BIGNUM *pub_key, DH *dh)
{
    int rv, pad;

#ifdef FIPS_MODE
    rv = compute_key(key, pub_key, dh);
#else
    rv = dh->meth->compute_key(key, pub_key, dh);
#endif
    if (rv <= 0)
        return rv;
    pad = BN_num_bytes(dh->params.p) - rv;
    if (pad > 0) {
        memmove(key + pad, key, rv);
        memset(key, 0, pad);
    }
    return rv + pad;
}

static DH_METHOD dh_ossl = {
    "OpenSSL DH Method",
    generate_key,
    compute_key,
    dh_bn_mod_exp,
    dh_init,
    dh_finish,
    DH_FLAG_FIPS_METHOD,
    NULL,
    NULL
};

static const DH_METHOD *default_DH_method = &dh_ossl;

const DH_METHOD *DH_OpenSSL(void)
{
    return &dh_ossl;
}

const DH_METHOD *DH_get_default_method(void)
{
    return default_DH_method;
}

static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
                         const BIGNUM *a, const BIGNUM *p,
                         const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx)
{
    return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
}

static int dh_init(DH *dh)
{
    dh->flags |= DH_FLAG_CACHE_MONT_P;
    ffc_params_init(&dh->params);
    dh->dirty_cnt++;
    return 1;
}

static int dh_finish(DH *dh)
{
    BN_MONT_CTX_free(dh->method_mont_p);
    return 1;
}

#ifndef FIPS_MODE
void DH_set_default_method(const DH_METHOD *meth)
{
    default_DH_method = meth;
}
#endif /* FIPS_MODE */

int DH_generate_key(DH *dh)
{
#ifdef FIPS_MODE
    return generate_key(dh);
#else
    return dh->meth->generate_key(dh);
#endif
}

int dh_generate_public_key(BN_CTX *ctx, DH *dh, const BIGNUM *priv_key,
                           BIGNUM *pub_key)
{
    int ret = 0;
    BIGNUM *prk = BN_new();
    BN_MONT_CTX *mont = NULL;

    if (prk == NULL)
        return 0;

    if (dh->flags & DH_FLAG_CACHE_MONT_P) {
        mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
                                      dh->lock, dh->params.p, ctx);
        if (mont == NULL)
            goto err;
    }
    BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);

    /* pub_key = g^priv_key mod p */
    if (!dh->meth->bn_mod_exp(dh, pub_key, dh->params.g, prk, dh->params.p,
                              ctx, mont))
        goto err;
    ret = 1;
err:
    BN_clear_free(prk);
    return ret;
}

static int generate_key(DH *dh)
{
    int ok = 0;
    int generate_new_key = 0;
#ifndef FIPS_MODE
    unsigned l;
#endif
    BN_CTX *ctx = NULL;
    BIGNUM *pub_key = NULL, *priv_key = NULL;

    if (BN_num_bits(dh->params.p) > OPENSSL_DH_MAX_MODULUS_BITS) {
        DHerr(0, DH_R_MODULUS_TOO_LARGE);
        return 0;
    }

    if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS) {
        DHerr(0, DH_R_MODULUS_TOO_SMALL);
        return 0;
    }

    ctx = BN_CTX_new_ex(dh->libctx);
    if (ctx == NULL)
        goto err;

    if (dh->priv_key == NULL) {
        priv_key = BN_secure_new();
        if (priv_key == NULL)
            goto err;
        generate_new_key = 1;
    } else {
        priv_key = dh->priv_key;
    }

    if (dh->pub_key == NULL) {
        pub_key = BN_new();
        if (pub_key == NULL)
            goto err;
    } else {
        pub_key = dh->pub_key;
    }
    if (generate_new_key) {
        /* Is it an approved safe prime ?*/
        if (DH_get_nid(dh) != NID_undef) {
            /*
             * The safe prime group code sets N = 2*s
             * (where s = max security strength supported).
             * N = dh->length (N = maximum bit length of private key)
             */
            if (dh->length == 0
                || dh->params.q == NULL
                || dh->length > BN_num_bits(dh->params.q))
                goto err;
            if (!ffc_generate_private_key(ctx, &dh->params, dh->length,
                                          dh->length / 2, priv_key))
                goto err;
        } else {
#ifdef FIPS_MODE
            if (dh->params.q == NULL)
                goto err;
#else
            if (dh->params.q == NULL) {
                /* secret exponent length */
                l = dh->length ? dh->length : BN_num_bits(dh->params.p) - 1;
                if (!BN_priv_rand_ex(priv_key, l, BN_RAND_TOP_ONE,
                                     BN_RAND_BOTTOM_ANY, ctx))
                    goto err;
                /*
                 * We handle just one known case where g is a quadratic non-residue:
                 * for g = 2: p % 8 == 3
                 */
                if (BN_is_word(dh->params.g, DH_GENERATOR_2)
                    && !BN_is_bit_set(dh->params.p, 2)) {
                    /* clear bit 0, since it won't be a secret anyway */
                    if (!BN_clear_bit(priv_key, 0))
                        goto err;
                }
            } else
#endif
            {
                /*
                 * For FFC FIPS 186-4 keygen
                 * security strength s = 112,
                 * Max Private key size N = len(q)
                 */
                if (!ffc_generate_private_key(ctx, &dh->params,
                                              BN_num_bits(dh->params.q), 112,
                                              priv_key))
                    goto err;
            }
        }
    }

    if (!dh_generate_public_key(ctx, dh, priv_key, pub_key))
        goto err;

    dh->pub_key = pub_key;
    dh->priv_key = priv_key;
    dh->dirty_cnt++;
    ok = 1;
 err:
    if (ok != 1)
        DHerr(0, ERR_R_BN_LIB);

    if (pub_key != dh->pub_key)
        BN_free(pub_key);
    if (priv_key != dh->priv_key)
        BN_free(priv_key);
    BN_CTX_free(ctx);
    return ok;
}

int dh_buf2key(DH *dh, const unsigned char *buf, size_t len)
{
    int err_reason = DH_R_BN_ERROR;
    BIGNUM *pubkey = NULL;
    const BIGNUM *p;
    size_t p_size;

    if ((pubkey = BN_bin2bn(buf, len, NULL)) == NULL)
        goto err;
    DH_get0_pqg(dh, &p, NULL, NULL);
    if (p == NULL || (p_size = BN_num_bytes(p)) == 0) {
        err_reason = DH_R_NO_PARAMETERS_SET;
        goto err;
    }
    /*
     * As per Section 4.2.8.1 of RFC 8446 fail if DHE's
     * public key is of size not equal to size of p
     */
    if (BN_is_zero(pubkey) || p_size != len) {
        err_reason = DH_R_INVALID_PUBKEY;
        goto err;
    }
    if (DH_set0_key(dh, pubkey, NULL) != 1)
        goto err;
    return 1;
err:
    DHerr(DH_F_DH_BUF2KEY, err_reason);
    BN_free(pubkey);
    return 0;
}

size_t dh_key2buf(const DH *dh, unsigned char **pbuf_out)
{
    const BIGNUM *pubkey;
    unsigned char *pbuf;
    const BIGNUM *p;
    int p_size;

    DH_get0_pqg(dh, &p, NULL, NULL);
    DH_get0_key(dh, &pubkey, NULL);
    if (p == NULL || pubkey == NULL
            || (p_size = BN_num_bytes(p)) == 0
            || BN_num_bytes(pubkey) == 0) {
        DHerr(DH_F_DH_KEY2BUF, DH_R_INVALID_PUBKEY);
        return 0;
    }
    if ((pbuf = OPENSSL_malloc(p_size)) == NULL) {
        DHerr(DH_F_DH_KEY2BUF, ERR_R_MALLOC_FAILURE);
        return 0;
    }
    /*
     * As per Section 4.2.8.1 of RFC 8446 left pad public
     * key with zeros to the size of p
     */
    if (BN_bn2binpad(pubkey, pbuf, p_size) < 0) {
        OPENSSL_free(pbuf);
        DHerr(DH_F_DH_KEY2BUF, DH_R_BN_ERROR);
        return 0;
    }
    *pbuf_out = pbuf;
    return p_size;
}
Commit	Line	Data
aa6bb135	1	/*
f11f86f6	2	* Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
d02b48c6	3	*
e38873f5	4	* Licensed under the Apache License 2.0 (the "License"). You may not use
aa6bb135 RS	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
d02b48c6 RE	8	*/
	9
	10	#include <stdio.h>
b39fc560	11	#include "internal/cryptlib.h"
706457b7	12	#include "dh_local.h"
25f2138b	13	#include "crypto/bn.h"
62f49b90	14	#include "crypto/dh.h"
d02b48c6	15
13066cee	16	static int generate_key(DH *dh);
f971ccb2	17	static int dh_bn_mod_exp(const DH dh, BIGNUM r,
0f113f3e MC	18	const BIGNUM a, const BIGNUM p,
0f113f3e MC	19	const BIGNUM m, BN_CTX ctx, BN_MONT_CTX *m_ctx);
13066cee DSH	20	static int dh_init(DH *dh);
	21	static int dh_finish(DH *dh);
	22
8083fd3a	23	static int compute_key(unsigned char key, const BIGNUM pub_key, DH *dh)
0f113f3e	24	{
62f49b90 SL	25	BN_CTX *ctx = NULL;
	26	BN_MONT_CTX *mont = NULL;
	27	BIGNUM *tmp;
	28	int ret = -1;
	29	#ifndef FIPS_MODE
	30	int check_result;
	31	#endif
	32
dc8de3e6	33	if (BN_num_bits(dh->params.p) > OPENSSL_DH_MAX_MODULUS_BITS) {
62f49b90 SL	34	DHerr(0, DH_R_MODULUS_TOO_LARGE);
	35	goto err;
	36	}
	37
dc8de3e6	38	if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS) {
62f49b90 SL	39	DHerr(0, DH_R_MODULUS_TOO_SMALL);
	40	return 0;
	41	}
	42
8083fd3a	43	ctx = BN_CTX_new_ex(dh->libctx);
62f49b90 SL	44	if (ctx == NULL)
	45	goto err;
	46	BN_CTX_start(ctx);
	47	tmp = BN_CTX_get(ctx);
	48	if (tmp == NULL)
	49	goto err;
	50
	51	if (dh->priv_key == NULL) {
	52	DHerr(0, DH_R_NO_PRIVATE_VALUE);
	53	goto err;
	54	}
	55
	56	if (dh->flags & DH_FLAG_CACHE_MONT_P) {
	57	mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
dc8de3e6	58	dh->lock, dh->params.p, ctx);
62f49b90 SL	59	BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME);
	60	if (!mont)
	61	goto err;
	62	}
	63	/* TODO(3.0) : Solve in a PR related to Key validation for DH */
	64	#ifndef FIPS_MODE
	65	if (!DH_check_pub_key(dh, pub_key, &check_result) \|\| check_result) {
	66	DHerr(0, DH_R_INVALID_PUBKEY);
	67	goto err;
	68	}
	69	#endif
dc8de3e6	70	if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key, dh->params.p, ctx,
62f49b90 SL	71	mont)) {
	72	DHerr(0, ERR_R_BN_LIB);
	73	goto err;
	74	}
	75
	76	ret = BN_bn2bin(tmp, key);
	77	err:
	78	BN_CTX_end(ctx);
	79	BN_CTX_free(ctx);
	80	return ret;
0f113f3e	81	}
13066cee	82
8083fd3a	83	int DH_compute_key(unsigned char key, const BIGNUM pub_key, DH *dh)
0f113f3e	84	{
8083fd3a SL	85	#ifdef FIPS_MODE
	86	return compute_key(key, pub_key, dh);
	87	#else
	88	return dh->meth->compute_key(key, pub_key, dh);
	89	#endif
0f113f3e	90	}
13066cee	91
8083fd3a	92	int DH_compute_key_padded(unsigned char key, const BIGNUM pub_key, DH *dh)
0f113f3e MC	93	{
0f113f3e MC	94	int rv, pad;
62f49b90 SL	95
62f49b90 SL	96	#ifdef FIPS_MODE
8083fd3a	97	rv = compute_key(key, pub_key, dh);
62f49b90	98	#else
0f113f3e	99	rv = dh->meth->compute_key(key, pub_key, dh);
62f49b90	100	#endif
0f113f3e MC	101	if (rv <= 0)
0f113f3e MC	102	return rv;
dc8de3e6	103	pad = BN_num_bytes(dh->params.p) - rv;
0f113f3e MC	104	if (pad > 0) {
	105	memmove(key + pad, key, rv);
	106	memset(key, 0, pad);
	107	}
	108	return rv + pad;
	109	}
bc91494e	110
13066cee	111	static DH_METHOD dh_ossl = {
0f113f3e MC	112	"OpenSSL DH Method",
	113	generate_key,
	114	compute_key,
	115	dh_bn_mod_exp,
	116	dh_init,
	117	dh_finish,
	118	DH_FLAG_FIPS_METHOD,
	119	NULL,
	120	NULL
13066cee DSH	121	};
13066cee DSH	122
076fc555 RS	123	static const DH_METHOD *default_DH_method = &dh_ossl;
076fc555 RS	124
f971ccb2	125	const DH_METHOD *DH_OpenSSL(void)
13066cee	126	{
0f113f3e	127	return &dh_ossl;
13066cee DSH	128	}
13066cee DSH	129
62f49b90 SL	130	const DH_METHOD *DH_get_default_method(void)
	131	{
	132	return default_DH_method;
	133	}
	134
	135	static int dh_bn_mod_exp(const DH dh, BIGNUM r,
	136	const BIGNUM a, const BIGNUM p,
	137	const BIGNUM m, BN_CTX ctx, BN_MONT_CTX *m_ctx)
	138	{
	139	return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
	140	}
	141
	142	static int dh_init(DH *dh)
	143	{
	144	dh->flags \|= DH_FLAG_CACHE_MONT_P;
dc8de3e6	145	ffc_params_init(&dh->params);
f11f86f6	146	dh->dirty_cnt++;
62f49b90 SL	147	return 1;
	148	}
	149
	150	static int dh_finish(DH *dh)
	151	{
	152	BN_MONT_CTX_free(dh->method_mont_p);
	153	return 1;
	154	}
	155
	156	#ifndef FIPS_MODE
076fc555 RS	157	void DH_set_default_method(const DH_METHOD *meth)
	158	{
	159	default_DH_method = meth;
	160	}
8083fd3a	161	#endif /* FIPS_MODE */
076fc555	162
62f49b90	163	int DH_generate_key(DH *dh)
076fc555	164	{
8083fd3a SL	165	#ifdef FIPS_MODE
	166	return generate_key(dh);
	167	#else
62f49b90	168	return dh->meth->generate_key(dh);
8083fd3a	169	#endif
076fc555 RS	170	}
076fc555 RS	171
8083fd3a SL	172	int dh_generate_public_key(BN_CTX ctx, DH dh, const BIGNUM *priv_key,
	173	BIGNUM *pub_key)
	174	{
	175	int ret = 0;
	176	BIGNUM *prk = BN_new();
	177	BN_MONT_CTX *mont = NULL;
	178
	179	if (prk == NULL)
	180	return 0;
	181
	182	if (dh->flags & DH_FLAG_CACHE_MONT_P) {
	183	mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
	184	dh->lock, dh->params.p, ctx);
	185	if (mont == NULL)
	186	goto err;
	187	}
	188	BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
	189
	190	/* pub_key = g^priv_key mod p */
	191	if (!dh->meth->bn_mod_exp(dh, pub_key, dh->params.g, prk, dh->params.p,
	192	ctx, mont))
	193	goto err;
	194	ret = 1;
	195	err:
	196	BN_clear_free(prk);
	197	return ret;
	198	}
	199
	200	static int generate_key(DH *dh)
0f113f3e MC	201	{
	202	int ok = 0;
	203	int generate_new_key = 0;
f11f86f6	204	#ifndef FIPS_MODE
0f113f3e	205	unsigned l;
f11f86f6	206	#endif
91f7361f	207	BN_CTX *ctx = NULL;
0f113f3e	208	BIGNUM pub_key = NULL, priv_key = NULL;
d02b48c6	209
dc8de3e6	210	if (BN_num_bits(dh->params.p) > OPENSSL_DH_MAX_MODULUS_BITS) {
f11f86f6	211	DHerr(0, DH_R_MODULUS_TOO_LARGE);
91f7361f GV	212	return 0;
	213	}
	214
dc8de3e6	215	if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS) {
f11f86f6	216	DHerr(0, DH_R_MODULUS_TOO_SMALL);
6de1fe90 BE	217	return 0;
	218	}
	219
8083fd3a	220	ctx = BN_CTX_new_ex(dh->libctx);
0f113f3e MC	221	if (ctx == NULL)
0f113f3e MC	222	goto err;
d02b48c6	223
0f113f3e	224	if (dh->priv_key == NULL) {
74924dcb	225	priv_key = BN_secure_new();
0f113f3e MC	226	if (priv_key == NULL)
	227	goto err;
	228	generate_new_key = 1;
8083fd3a	229	} else {
0f113f3e	230	priv_key = dh->priv_key;
8083fd3a	231	}
d02b48c6	232
0f113f3e MC	233	if (dh->pub_key == NULL) {
	234	pub_key = BN_new();
	235	if (pub_key == NULL)
	236	goto err;
8083fd3a	237	} else {
0f113f3e	238	pub_key = dh->pub_key;
0f113f3e	239	}
0f113f3e	240	if (generate_new_key) {
f11f86f6 SL	241	/* Is it an approved safe prime ?*/
f11f86f6 SL	242	if (DH_get_nid(dh) != NID_undef) {
a38c878c	243	/*
f11f86f6 SL	244	* The safe prime group code sets N = 2*s
	245	* (where s = max security strength supported).
	246	* N = dh->length (N = maximum bit length of private key)
a38c878c	247	*/
f11f86f6 SL	248	if (dh->length == 0
	249	\|\| dh->params.q == NULL
	250	\|\| dh->length > BN_num_bits(dh->params.q))
	251	goto err;
	252	if (!ffc_generate_private_key(ctx, &dh->params, dh->length,
	253	dh->length / 2, priv_key))
	254	goto err;
	255	} else {
	256	#ifdef FIPS_MODE
	257	if (dh->params.q == NULL)
	258	goto err;
	259	#else
	260	if (dh->params.q == NULL) {
	261	/* secret exponent length */
	262	l = dh->length ? dh->length : BN_num_bits(dh->params.p) - 1;
	263	if (!BN_priv_rand_ex(priv_key, l, BN_RAND_TOP_ONE,
	264	BN_RAND_BOTTOM_ANY, ctx))
	265	goto err;
	266	/*
	267	* We handle just one known case where g is a quadratic non-residue:
	268	* for g = 2: p % 8 == 3
	269	*/
	270	if (BN_is_word(dh->params.g, DH_GENERATOR_2)
	271	&& !BN_is_bit_set(dh->params.p, 2)) {
	272	/* clear bit 0, since it won't be a secret anyway */
	273	if (!BN_clear_bit(priv_key, 0))
	274	goto err;
	275	}
	276	} else
	277	#endif
	278	{
	279	/*
	280	* For FFC FIPS 186-4 keygen
	281	* security strength s = 112,
	282	* Max Private key size N = len(q)
	283	*/
	284	if (!ffc_generate_private_key(ctx, &dh->params,
	285	BN_num_bits(dh->params.q), 112,
	286	priv_key))
a38c878c BE	287	goto err;
a38c878c BE	288	}
0f113f3e MC	289	}
0f113f3e MC	290	}
dfeab068	291
8083fd3a SL	292	if (!dh_generate_public_key(ctx, dh, priv_key, pub_key))
8083fd3a SL	293	goto err;
46a64376	294
0f113f3e MC	295	dh->pub_key = pub_key;
0f113f3e MC	296	dh->priv_key = priv_key;
8b84b075	297	dh->dirty_cnt++;
0f113f3e MC	298	ok = 1;
	299	err:
	300	if (ok != 1)
f11f86f6	301	DHerr(0, ERR_R_BN_LIB);
d02b48c6	302
23a1d5e9	303	if (pub_key != dh->pub_key)
0f113f3e	304	BN_free(pub_key);
23a1d5e9	305	if (priv_key != dh->priv_key)
0f113f3e MC	306	BN_free(priv_key);
0f113f3e MC	307	BN_CTX_free(ctx);
26a7d938	308	return ok;
0f113f3e	309	}
d02b48c6	310
9aaecbfc	311	int dh_buf2key(DH dh, const unsigned char buf, size_t len)
	312	{
	313	int err_reason = DH_R_BN_ERROR;
	314	BIGNUM *pubkey = NULL;
	315	const BIGNUM *p;
	316	size_t p_size;
	317
	318	if ((pubkey = BN_bin2bn(buf, len, NULL)) == NULL)
	319	goto err;
	320	DH_get0_pqg(dh, &p, NULL, NULL);
	321	if (p == NULL \|\| (p_size = BN_num_bytes(p)) == 0) {
	322	err_reason = DH_R_NO_PARAMETERS_SET;
	323	goto err;
	324	}
	325	/*
	326	* As per Section 4.2.8.1 of RFC 8446 fail if DHE's
	327	* public key is of size not equal to size of p
	328	*/
	329	if (BN_is_zero(pubkey) \|\| p_size != len) {
	330	err_reason = DH_R_INVALID_PUBKEY;
	331	goto err;
	332	}
	333	if (DH_set0_key(dh, pubkey, NULL) != 1)
	334	goto err;
	335	return 1;
	336	err:
	337	DHerr(DH_F_DH_BUF2KEY, err_reason);
	338	BN_free(pubkey);
	339	return 0;
	340	}
	341
	342	size_t dh_key2buf(const DH dh, unsigned char *pbuf_out)
	343	{
	344	const BIGNUM *pubkey;
	345	unsigned char *pbuf;
	346	const BIGNUM *p;
	347	int p_size;
	348
	349	DH_get0_pqg(dh, &p, NULL, NULL);
	350	DH_get0_key(dh, &pubkey, NULL);
	351	if (p == NULL \|\| pubkey == NULL
	352	\|\| (p_size = BN_num_bytes(p)) == 0
	353	\|\| BN_num_bytes(pubkey) == 0) {
	354	DHerr(DH_F_DH_KEY2BUF, DH_R_INVALID_PUBKEY);
	355	return 0;
	356	}
	357	if ((pbuf = OPENSSL_malloc(p_size)) == NULL) {
	358	DHerr(DH_F_DH_KEY2BUF, ERR_R_MALLOC_FAILURE);
	359	return 0;
	360	}
	361	/*
	362	* As per Section 4.2.8.1 of RFC 8446 left pad public
	363	* key with zeros to the size of p
	364	*/
	365	if (BN_bn2binpad(pubkey, pbuf, p_size) < 0) {
	366	OPENSSL_free(pbuf);
	367	DHerr(DH_F_DH_KEY2BUF, DH_R_BN_ERROR);
	368	return 0;
	369	}
	370	*pbuf_out = pbuf;
	371	return p_size;
	372	}