[deb_ffmpeg.git] / ffmpeg / libavformat / rtmpdh.c

/*
 * RTMP Diffie-Hellmann utilities
 * Copyright (c) 2009 Andrej Stepanchuk
 * Copyright (c) 2009-2010 Howard Chu
 * Copyright (c) 2012 Samuel Pitoiset
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * RTMP Diffie-Hellmann utilities
 */

#include "config.h"
#include "rtmpdh.h"
#include "libavutil/random_seed.h"

#define P1024                                          \
    "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1" \
    "29024E088A67CC74020BBEA63B139B22514A08798E3404DD" \
    "EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245" \
    "E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED" \
    "EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381" \
    "FFFFFFFFFFFFFFFF"

#define Q1024                                          \
    "7FFFFFFFFFFFFFFFE487ED5110B4611A62633145C06E0E68" \
    "948127044533E63A0105DF531D89CD9128A5043CC71A026E" \
    "F7CA8CD9E69D218D98158536F92F8A1BA7F09AB6B6A8E122" \
    "F242DABB312F3F637A262174D31BF6B585FFAE5B7A035BF6" \
    "F71C35FDAD44CFD2D74F9208BE258FF324943328F67329C0" \
    "FFFFFFFFFFFFFFFF"

#if CONFIG_NETTLE || CONFIG_GCRYPT
#if CONFIG_NETTLE
#define bn_new(bn)                      \
    do {                                \
        bn = av_malloc(sizeof(*bn));    \
        if (bn)                         \
            mpz_init2(bn, 1);           \
    } while (0)
#define bn_free(bn)     \
    do {                \
        mpz_clear(bn);  \
        av_free(bn);    \
    } while (0)
#define bn_set_word(bn, w)          mpz_set_ui(bn, w)
#define bn_cmp(a, b)                mpz_cmp(a, b)
#define bn_copy(to, from)           mpz_set(to, from)
#define bn_sub_word(bn, w)          mpz_sub_ui(bn, bn, w)
#define bn_cmp_1(bn)                mpz_cmp_ui(bn, 1)
#define bn_num_bytes(bn)            (mpz_sizeinbase(bn, 2) + 7) / 8
#define bn_bn2bin(bn, buf, len)     nettle_mpz_get_str_256(len, buf, bn)
#define bn_bin2bn(bn, buf, len)                     \
    do {                                            \
        bn_new(bn);                                 \
        if (bn)                                     \
            nettle_mpz_set_str_256_u(bn, len, buf); \
    } while (0)
#define bn_hex2bn(bn, buf, ret)                     \
    do {                                            \
        bn_new(bn);                                 \
        if (bn)                                     \
            ret = (mpz_set_str(bn, buf, 16) == 0);  \
    } while (0)
#define bn_modexp(bn, y, q, p)      mpz_powm(bn, y, q, p)
#define bn_random(bn, num_bytes)                    \
    do {                                            \
        gmp_randstate_t rs;                         \
        gmp_randinit_mt(rs);                        \
        gmp_randseed_ui(rs, av_get_random_seed());  \
        mpz_urandomb(bn, rs, num_bytes);            \
        gmp_randclear(rs);                          \
    } while (0)
#elif CONFIG_GCRYPT
#define bn_new(bn)                  bn = gcry_mpi_new(1)
#define bn_free(bn)                 gcry_mpi_release(bn)
#define bn_set_word(bn, w)          gcry_mpi_set_ui(bn, w)
#define bn_cmp(a, b)                gcry_mpi_cmp(a, b)
#define bn_copy(to, from)           gcry_mpi_set(to, from)
#define bn_sub_word(bn, w)          gcry_mpi_sub_ui(bn, bn, w)
#define bn_cmp_1(bn)                gcry_mpi_cmp_ui(bn, 1)
#define bn_num_bytes(bn)            (gcry_mpi_get_nbits(bn) + 7) / 8
#define bn_bn2bin(bn, buf, len)     gcry_mpi_print(GCRYMPI_FMT_USG, buf, len, NULL, bn)
#define bn_bin2bn(bn, buf, len)     gcry_mpi_scan(&bn, GCRYMPI_FMT_USG, buf, len, NULL)
#define bn_hex2bn(bn, buf, ret)     ret = (gcry_mpi_scan(&bn, GCRYMPI_FMT_HEX, buf, 0, 0) == 0)
#define bn_modexp(bn, y, q, p)      gcry_mpi_powm(bn, y, q, p)
#define bn_random(bn, num_bytes)    gcry_mpi_randomize(bn, num_bytes, GCRY_WEAK_RANDOM)
#endif

#define MAX_BYTES 18000

#define dh_new()                    av_malloc(sizeof(FF_DH))

static FFBigNum dh_generate_key(FF_DH *dh)
{
    int num_bytes;

    num_bytes = bn_num_bytes(dh->p) - 1;
    if (num_bytes <= 0 || num_bytes > MAX_BYTES)
        return NULL;

    bn_new(dh->priv_key);
    if (!dh->priv_key)
        return NULL;
    bn_random(dh->priv_key, num_bytes);

    bn_new(dh->pub_key);
    if (!dh->pub_key) {
        bn_free(dh->priv_key);
        return NULL;
    }

    bn_modexp(dh->pub_key, dh->g, dh->priv_key, dh->p);

    return dh->pub_key;
}

static int dh_compute_key(FF_DH *dh, FFBigNum pub_key_bn,
                          uint32_t pub_key_len, uint8_t *secret_key)
{
    FFBigNum k;
    int num_bytes;

    num_bytes = bn_num_bytes(dh->p);
    if (num_bytes <= 0 || num_bytes > MAX_BYTES)
        return -1;

    bn_new(k);
    if (!k)
        return -1;

    bn_modexp(k, pub_key_bn, dh->priv_key, dh->p);
    bn_bn2bin(k, secret_key, pub_key_len);
    bn_free(k);

    /* return the length of the shared secret key like DH_compute_key */
    return pub_key_len;
}

void ff_dh_free(FF_DH *dh)
{
    bn_free(dh->p);
    bn_free(dh->g);
    bn_free(dh->pub_key);
    bn_free(dh->priv_key);
    av_free(dh);
}
#elif CONFIG_OPENSSL
#define bn_new(bn)                  bn = BN_new()
#define bn_free(bn)                 BN_free(bn)
#define bn_set_word(bn, w)          BN_set_word(bn, w)
#define bn_cmp(a, b)                BN_cmp(a, b)
#define bn_copy(to, from)           BN_copy(to, from)
#define bn_sub_word(bn, w)          BN_sub_word(bn, w)
#define bn_cmp_1(bn)                BN_cmp(bn, BN_value_one())
#define bn_num_bytes(bn)            BN_num_bytes(bn)
#define bn_bn2bin(bn, buf, len)     BN_bn2bin(bn, buf)
#define bn_bin2bn(bn, buf, len)     bn = BN_bin2bn(buf, len, 0)
#define bn_hex2bn(bn, buf, ret)     ret = BN_hex2bn(&bn, buf)
#define bn_modexp(bn, y, q, p)               \
    do {                                     \
        BN_CTX *ctx = BN_CTX_new();          \
        if (!ctx)                            \
            return AVERROR(ENOMEM);          \
        if (!BN_mod_exp(bn, y, q, p, ctx)) { \
            BN_CTX_free(ctx);                \
            return AVERROR(EINVAL);          \
        }                                    \
        BN_CTX_free(ctx);                    \
    } while (0)

#define dh_new()                                DH_new()
#define dh_generate_key(dh)                     DH_generate_key(dh)
#define dh_compute_key(dh, pub, len, secret)    DH_compute_key(secret, pub, dh)

void ff_dh_free(FF_DH *dh)
{
    DH_free(dh);
}
#endif

static int dh_is_valid_public_key(FFBigNum y, FFBigNum p, FFBigNum q)
{
    FFBigNum bn = NULL;
    int ret = AVERROR(EINVAL);

    bn_new(bn);
    if (!bn)
        return AVERROR(ENOMEM);

    /* y must lie in [2, p - 1] */
    bn_set_word(bn, 1);
    if (!bn_cmp(y, bn))
        goto fail;

    /* bn = p - 2 */
    bn_copy(bn, p);
    bn_sub_word(bn, 1);
    if (!bn_cmp(y, bn))
        goto fail;

    /* Verify with Sophie-Germain prime
     *
     * This is a nice test to make sure the public key position is calculated
     * correctly. This test will fail in about 50% of the cases if applied to
     * random data.
     */
    /* y must fulfill y^q mod p = 1 */
    bn_modexp(bn, y, q, p);

    if (bn_cmp_1(bn))
        goto fail;

    ret = 0;
fail:
    bn_free(bn);

    return ret;
}

av_cold FF_DH *ff_dh_init(int key_len)
{
    FF_DH *dh;
    int ret;

    if (!(dh = dh_new()))
        return NULL;

    bn_new(dh->g);
    if (!dh->g)
        goto fail;

    bn_hex2bn(dh->p, P1024, ret);
    if (!ret)
        goto fail;

    bn_set_word(dh->g, 2);
    dh->length = key_len;

    return dh;

fail:
    ff_dh_free(dh);

    return NULL;
}

int ff_dh_generate_public_key(FF_DH *dh)
{
    int ret = 0;

    while (!ret) {
        FFBigNum q1 = NULL;

        if (!dh_generate_key(dh))
            return AVERROR(EINVAL);

        bn_hex2bn(q1, Q1024, ret);
        if (!ret)
            return AVERROR(ENOMEM);

        ret = dh_is_valid_public_key(dh->pub_key, dh->p, q1);
        bn_free(q1);

        if (!ret) {
            /* the public key is valid */
            break;
        }
    }

    return ret;
}

int ff_dh_write_public_key(FF_DH *dh, uint8_t *pub_key, int pub_key_len)
{
    int len;

    /* compute the length of the public key */
    len = bn_num_bytes(dh->pub_key);
    if (len <= 0 || len > pub_key_len)
        return AVERROR(EINVAL);

    /* convert the public key value into big-endian form */
    memset(pub_key, 0, pub_key_len);
    bn_bn2bin(dh->pub_key, pub_key + pub_key_len - len, len);

    return 0;
}

int ff_dh_compute_shared_secret_key(FF_DH *dh, const uint8_t *pub_key,
                                    int pub_key_len, uint8_t *secret_key)
{
    FFBigNum q1 = NULL, pub_key_bn = NULL;
    int ret;

    /* convert the big-endian form of the public key into a bignum */
    bn_bin2bn(pub_key_bn, pub_key, pub_key_len);
    if (!pub_key_bn)
        return AVERROR(ENOMEM);

    /* convert the string containing a hexadecimal number into a bignum */
    bn_hex2bn(q1, Q1024, ret);
    if (!ret) {
        ret = AVERROR(ENOMEM);
        goto fail;
    }

    /* when the public key is valid we have to compute the shared secret key */
    if ((ret = dh_is_valid_public_key(pub_key_bn, dh->p, q1)) < 0) {
        goto fail;
    } else if ((ret = dh_compute_key(dh, pub_key_bn, pub_key_len,
                                     secret_key)) < 0) {
        ret = AVERROR(EINVAL);
        goto fail;
    }

fail:
    bn_free(pub_key_bn);
    bn_free(q1);

    return ret;
}
Commit	Line	Data
2ba45a60 DM	1	/*
	2	* RTMP Diffie-Hellmann utilities
	3	* Copyright (c) 2009 Andrej Stepanchuk
	4	* Copyright (c) 2009-2010 Howard Chu
	5	* Copyright (c) 2012 Samuel Pitoiset
	6	*
	7	* This file is part of FFmpeg.
	8	*
	9	* FFmpeg is free software; you can redistribute it and/or
	10	* modify it under the terms of the GNU Lesser General Public
	11	* License as published by the Free Software Foundation; either
	12	* version 2.1 of the License, or (at your option) any later version.
	13	*
	14	* FFmpeg is distributed in the hope that it will be useful,
	15	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	16	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	17	* Lesser General Public License for more details.
	18	*
	19	* You should have received a copy of the GNU Lesser General Public
	20	* License along with FFmpeg; if not, write to the Free Software
	21	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	22	*/
	23
	24	/**
	25	* @file
	26	* RTMP Diffie-Hellmann utilities
	27	*/
	28
	29	#include "config.h"
	30	#include "rtmpdh.h"
	31	#include "libavutil/random_seed.h"
	32
	33	#define P1024 \
	34	"FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1" \
	35	"29024E088A67CC74020BBEA63B139B22514A08798E3404DD" \
	36	"EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245" \
	37	"E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED" \
	38	"EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381" \
	39	"FFFFFFFFFFFFFFFF"
	40
	41	#define Q1024 \
	42	"7FFFFFFFFFFFFFFFE487ED5110B4611A62633145C06E0E68" \
	43	"948127044533E63A0105DF531D89CD9128A5043CC71A026E" \
	44	"F7CA8CD9E69D218D98158536F92F8A1BA7F09AB6B6A8E122" \
	45	"F242DABB312F3F637A262174D31BF6B585FFAE5B7A035BF6" \
	46	"F71C35FDAD44CFD2D74F9208BE258FF324943328F67329C0" \
	47	"FFFFFFFFFFFFFFFF"
	48
	49	#if CONFIG_NETTLE \|\| CONFIG_GCRYPT
	50	#if CONFIG_NETTLE
	51	#define bn_new(bn) \
	52	do { \
	53	bn = av_malloc(sizeof(*bn)); \
	54	if (bn) \
	55	mpz_init2(bn, 1); \
	56	} while (0)
	57	#define bn_free(bn) \
	58	do { \
	59	mpz_clear(bn); \
	60	av_free(bn); \
	61	} while (0)
	62	#define bn_set_word(bn, w) mpz_set_ui(bn, w)
	63	#define bn_cmp(a, b) mpz_cmp(a, b)
	64	#define bn_copy(to, from) mpz_set(to, from)
65	#define bn_sub_word(bn, w) mpz_sub_ui(bn, bn, w)
66	#define bn_cmp_1(bn) mpz_cmp_ui(bn, 1)
67	#define bn_num_bytes(bn) (mpz_sizeinbase(bn, 2) + 7) / 8
68	#define bn_bn2bin(bn, buf, len) nettle_mpz_get_str_256(len, buf, bn)
69	#define bn_bin2bn(bn, buf, len) \
70	do { \
71	bn_new(bn); \
72	if (bn) \
73	nettle_mpz_set_str_256_u(bn, len, buf); \
74	} while (0)
75	#define bn_hex2bn(bn, buf, ret) \
76	do { \
77	bn_new(bn); \
78	if (bn) \
79	ret = (mpz_set_str(bn, buf, 16) == 0); \
80	} while (0)
81	#define bn_modexp(bn, y, q, p) mpz_powm(bn, y, q, p)
82	#define bn_random(bn, num_bytes) \
83	do { \
84	gmp_randstate_t rs; \
85	gmp_randinit_mt(rs); \
86	gmp_randseed_ui(rs, av_get_random_seed()); \
87	mpz_urandomb(bn, rs, num_bytes); \
88	gmp_randclear(rs); \
89	} while (0)
90	#elif CONFIG_GCRYPT
91	#define bn_new(bn) bn = gcry_mpi_new(1)
92	#define bn_free(bn) gcry_mpi_release(bn)
93	#define bn_set_word(bn, w) gcry_mpi_set_ui(bn, w)
94	#define bn_cmp(a, b) gcry_mpi_cmp(a, b)
95	#define bn_copy(to, from) gcry_mpi_set(to, from)
96	#define bn_sub_word(bn, w) gcry_mpi_sub_ui(bn, bn, w)
97	#define bn_cmp_1(bn) gcry_mpi_cmp_ui(bn, 1)
98	#define bn_num_bytes(bn) (gcry_mpi_get_nbits(bn) + 7) / 8
99	#define bn_bn2bin(bn, buf, len) gcry_mpi_print(GCRYMPI_FMT_USG, buf, len, NULL, bn)
100	#define bn_bin2bn(bn, buf, len) gcry_mpi_scan(&bn, GCRYMPI_FMT_USG, buf, len, NULL)
101	#define bn_hex2bn(bn, buf, ret) ret = (gcry_mpi_scan(&bn, GCRYMPI_FMT_HEX, buf, 0, 0) == 0)
102	#define bn_modexp(bn, y, q, p) gcry_mpi_powm(bn, y, q, p)
103	#define bn_random(bn, num_bytes) gcry_mpi_randomize(bn, num_bytes, GCRY_WEAK_RANDOM)
104	#endif
105
106	#define MAX_BYTES 18000
107
108	#define dh_new() av_malloc(sizeof(FF_DH))
109
110	static FFBigNum dh_generate_key(FF_DH *dh)
111	{
112	int num_bytes;
113
114	num_bytes = bn_num_bytes(dh->p) - 1;
115	if (num_bytes <= 0 \|\| num_bytes > MAX_BYTES)
116	return NULL;
117
118	bn_new(dh->priv_key);
119	if (!dh->priv_key)
120	return NULL;
121	bn_random(dh->priv_key, num_bytes);
122
123	bn_new(dh->pub_key);
124	if (!dh->pub_key) {
125	bn_free(dh->priv_key);
126	return NULL;
127	}
128
129	bn_modexp(dh->pub_key, dh->g, dh->priv_key, dh->p);
130
131	return dh->pub_key;
132	}
133
134	static int dh_compute_key(FF_DH *dh, FFBigNum pub_key_bn,
135	uint32_t pub_key_len, uint8_t *secret_key)
136	{
137	FFBigNum k;
138	int num_bytes;
139
140	num_bytes = bn_num_bytes(dh->p);
141	if (num_bytes <= 0 \|\| num_bytes > MAX_BYTES)
142	return -1;
143
144	bn_new(k);
145	if (!k)
146	return -1;
147
148	bn_modexp(k, pub_key_bn, dh->priv_key, dh->p);
149	bn_bn2bin(k, secret_key, pub_key_len);
150	bn_free(k);
151
152	/* return the length of the shared secret key like DH_compute_key */
153	return pub_key_len;
154	}
155
156	void ff_dh_free(FF_DH *dh)
157	{
158	bn_free(dh->p);
159	bn_free(dh->g);
160	bn_free(dh->pub_key);
161	bn_free(dh->priv_key);
162	av_free(dh);
163	}
164	#elif CONFIG_OPENSSL
165	#define bn_new(bn) bn = BN_new()
166	#define bn_free(bn) BN_free(bn)
167	#define bn_set_word(bn, w) BN_set_word(bn, w)
168	#define bn_cmp(a, b) BN_cmp(a, b)
169	#define bn_copy(to, from) BN_copy(to, from)
170	#define bn_sub_word(bn, w) BN_sub_word(bn, w)
171	#define bn_cmp_1(bn) BN_cmp(bn, BN_value_one())
172	#define bn_num_bytes(bn) BN_num_bytes(bn)
173	#define bn_bn2bin(bn, buf, len) BN_bn2bin(bn, buf)
174	#define bn_bin2bn(bn, buf, len) bn = BN_bin2bn(buf, len, 0)
175	#define bn_hex2bn(bn, buf, ret) ret = BN_hex2bn(&bn, buf)
176	#define bn_modexp(bn, y, q, p) \
177	do { \
178	BN_CTX *ctx = BN_CTX_new(); \
179	if (!ctx) \
180	return AVERROR(ENOMEM); \
181	if (!BN_mod_exp(bn, y, q, p, ctx)) { \
182	BN_CTX_free(ctx); \
183	return AVERROR(EINVAL); \
184	} \
185	BN_CTX_free(ctx); \
186	} while (0)
187
188	#define dh_new() DH_new()
189	#define dh_generate_key(dh) DH_generate_key(dh)
190	#define dh_compute_key(dh, pub, len, secret) DH_compute_key(secret, pub, dh)
191
192	void ff_dh_free(FF_DH *dh)
193	{
194	DH_free(dh);
195	}
196	#endif
197
198	static int dh_is_valid_public_key(FFBigNum y, FFBigNum p, FFBigNum q)
199	{
200	FFBigNum bn = NULL;
201	int ret = AVERROR(EINVAL);
202
203	bn_new(bn);
204	if (!bn)
205	return AVERROR(ENOMEM);
206
207	/* y must lie in [2, p - 1] */
208	bn_set_word(bn, 1);
209	if (!bn_cmp(y, bn))
210	goto fail;
211
212	/* bn = p - 2 */
213	bn_copy(bn, p);
214	bn_sub_word(bn, 1);
215	if (!bn_cmp(y, bn))
216	goto fail;
217
218	/* Verify with Sophie-Germain prime
219	*
220	* This is a nice test to make sure the public key position is calculated
221	* correctly. This test will fail in about 50% of the cases if applied to
222	* random data.
223	*/
224	/* y must fulfill y^q mod p = 1 */
225	bn_modexp(bn, y, q, p);
226
227	if (bn_cmp_1(bn))
228	goto fail;
229
230	ret = 0;
231	fail:
232	bn_free(bn);
233
234	return ret;
235	}
236
237	av_cold FF_DH *ff_dh_init(int key_len)
238	{
239	FF_DH *dh;
240	int ret;
241
242	if (!(dh = dh_new()))
243	return NULL;
244
245	bn_new(dh->g);
246	if (!dh->g)
247	goto fail;
248
249	bn_hex2bn(dh->p, P1024, ret);
250	if (!ret)
251	goto fail;
252
253	bn_set_word(dh->g, 2);
254	dh->length = key_len;
255
256	return dh;
257
258	fail:
259	ff_dh_free(dh);
260
261	return NULL;
262	}
263
264	int ff_dh_generate_public_key(FF_DH *dh)
265	{
266	int ret = 0;
267
268	while (!ret) {
269	FFBigNum q1 = NULL;
270
271	if (!dh_generate_key(dh))
272	return AVERROR(EINVAL);
273
274	bn_hex2bn(q1, Q1024, ret);
275	if (!ret)
276	return AVERROR(ENOMEM);
277
278	ret = dh_is_valid_public_key(dh->pub_key, dh->p, q1);
279	bn_free(q1);
280
281	if (!ret) {
282	/* the public key is valid */
283	break;
284	}
285	}
286
287	return ret;
288	}
289
290	int ff_dh_write_public_key(FF_DH dh, uint8_t pub_key, int pub_key_len)
291	{
292	int len;
293
294	/* compute the length of the public key */
295	len = bn_num_bytes(dh->pub_key);
296	if (len <= 0 \|\| len > pub_key_len)
297	return AVERROR(EINVAL);
298
299	/* convert the public key value into big-endian form */
300	memset(pub_key, 0, pub_key_len);
301	bn_bn2bin(dh->pub_key, pub_key + pub_key_len - len, len);
302
303	return 0;
304	}
305
306	int ff_dh_compute_shared_secret_key(FF_DH dh, const uint8_t pub_key,
307	int pub_key_len, uint8_t *secret_key)
308	{
309	FFBigNum q1 = NULL, pub_key_bn = NULL;
310	int ret;
311
312	/* convert the big-endian form of the public key into a bignum */
313	bn_bin2bn(pub_key_bn, pub_key, pub_key_len);
314	if (!pub_key_bn)
315	return AVERROR(ENOMEM);
316
317	/* convert the string containing a hexadecimal number into a bignum */
318	bn_hex2bn(q1, Q1024, ret);
319	if (!ret) {
320	ret = AVERROR(ENOMEM);
321	goto fail;
322	}
323
324	/* when the public key is valid we have to compute the shared secret key */
325	if ((ret = dh_is_valid_public_key(pub_key_bn, dh->p, q1)) < 0) {
326	goto fail;
327	} else if ((ret = dh_compute_key(dh, pub_key_bn, pub_key_len,
328	secret_key)) < 0) {
329	ret = AVERROR(EINVAL);
330	goto fail;
331	}
332
333	fail:
334	bn_free(pub_key_bn);
335	bn_free(q1);
336
337	return ret;
338	}
339