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Commit | Line | Data |
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aa6bb135 | 1 | /* |
a38c878c | 2 | * Copyright 1995-2019 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" |
0aeddcfa | 12 | #include "dh_locl.h" |
829ccf6a | 13 | #include "internal/bn_int.h" |
d02b48c6 | 14 | |
13066cee | 15 | static int generate_key(DH *dh); |
f971ccb2 RL |
16 | static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh); |
17 | static int dh_bn_mod_exp(const DH *dh, BIGNUM *r, | |
0f113f3e MC |
18 | const BIGNUM *a, const BIGNUM *p, |
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 | ||
6b691a5c | 23 | int DH_generate_key(DH *dh) |
0f113f3e MC |
24 | { |
25 | return dh->meth->generate_key(dh); | |
26 | } | |
13066cee | 27 | |
f971ccb2 | 28 | int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh) |
0f113f3e MC |
29 | { |
30 | return dh->meth->compute_key(key, pub_key, dh); | |
31 | } | |
13066cee | 32 | |
bc91494e | 33 | int DH_compute_key_padded(unsigned char *key, const BIGNUM *pub_key, DH *dh) |
0f113f3e MC |
34 | { |
35 | int rv, pad; | |
36 | rv = dh->meth->compute_key(key, pub_key, dh); | |
37 | if (rv <= 0) | |
38 | return rv; | |
39 | pad = BN_num_bytes(dh->p) - rv; | |
40 | if (pad > 0) { | |
41 | memmove(key + pad, key, rv); | |
42 | memset(key, 0, pad); | |
43 | } | |
44 | return rv + pad; | |
45 | } | |
bc91494e | 46 | |
13066cee | 47 | static DH_METHOD dh_ossl = { |
0f113f3e MC |
48 | "OpenSSL DH Method", |
49 | generate_key, | |
50 | compute_key, | |
51 | dh_bn_mod_exp, | |
52 | dh_init, | |
53 | dh_finish, | |
54 | DH_FLAG_FIPS_METHOD, | |
55 | NULL, | |
56 | NULL | |
13066cee DSH |
57 | }; |
58 | ||
076fc555 RS |
59 | static const DH_METHOD *default_DH_method = &dh_ossl; |
60 | ||
f971ccb2 | 61 | const DH_METHOD *DH_OpenSSL(void) |
13066cee | 62 | { |
0f113f3e | 63 | return &dh_ossl; |
13066cee DSH |
64 | } |
65 | ||
076fc555 RS |
66 | void DH_set_default_method(const DH_METHOD *meth) |
67 | { | |
68 | default_DH_method = meth; | |
69 | } | |
70 | ||
71 | const DH_METHOD *DH_get_default_method(void) | |
72 | { | |
73 | return default_DH_method; | |
74 | } | |
75 | ||
13066cee | 76 | static int generate_key(DH *dh) |
0f113f3e MC |
77 | { |
78 | int ok = 0; | |
79 | int generate_new_key = 0; | |
80 | unsigned l; | |
91f7361f | 81 | BN_CTX *ctx = NULL; |
0f113f3e MC |
82 | BN_MONT_CTX *mont = NULL; |
83 | BIGNUM *pub_key = NULL, *priv_key = NULL; | |
d02b48c6 | 84 | |
91f7361f GV |
85 | if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) { |
86 | DHerr(DH_F_GENERATE_KEY, DH_R_MODULUS_TOO_LARGE); | |
87 | return 0; | |
88 | } | |
89 | ||
0f113f3e MC |
90 | ctx = BN_CTX_new(); |
91 | if (ctx == NULL) | |
92 | goto err; | |
d02b48c6 | 93 | |
0f113f3e | 94 | if (dh->priv_key == NULL) { |
74924dcb | 95 | priv_key = BN_secure_new(); |
0f113f3e MC |
96 | if (priv_key == NULL) |
97 | goto err; | |
98 | generate_new_key = 1; | |
99 | } else | |
100 | priv_key = dh->priv_key; | |
d02b48c6 | 101 | |
0f113f3e MC |
102 | if (dh->pub_key == NULL) { |
103 | pub_key = BN_new(); | |
104 | if (pub_key == NULL) | |
105 | goto err; | |
106 | } else | |
107 | pub_key = dh->pub_key; | |
d02b48c6 | 108 | |
0f113f3e MC |
109 | if (dh->flags & DH_FLAG_CACHE_MONT_P) { |
110 | mont = BN_MONT_CTX_set_locked(&dh->method_mont_p, | |
d188a536 | 111 | dh->lock, dh->p, ctx); |
0f113f3e MC |
112 | if (!mont) |
113 | goto err; | |
114 | } | |
6ec8e63a | 115 | |
0f113f3e MC |
116 | if (generate_new_key) { |
117 | if (dh->q) { | |
118 | do { | |
ddc6a5c8 | 119 | if (!BN_priv_rand_range(priv_key, dh->q)) |
0f113f3e MC |
120 | goto err; |
121 | } | |
122 | while (BN_is_zero(priv_key) || BN_is_one(priv_key)); | |
123 | } else { | |
124 | /* secret exponent length */ | |
125 | l = dh->length ? dh->length : BN_num_bits(dh->p) - 1; | |
ddc6a5c8 | 126 | if (!BN_priv_rand(priv_key, l, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ANY)) |
0f113f3e | 127 | goto err; |
a38c878c BE |
128 | /* |
129 | * We handle just one known case where g is a quadratic non-residue: | |
130 | * for g = 2: p % 8 == 3 | |
131 | */ | |
132 | if (BN_is_word(dh->g, DH_GENERATOR_2) && !BN_is_bit_set(dh->p, 2)) { | |
133 | /* clear bit 0, since it won't be a secret anyway */ | |
134 | if (!BN_clear_bit(priv_key, 0)) | |
135 | goto err; | |
136 | } | |
0f113f3e MC |
137 | } |
138 | } | |
dfeab068 | 139 | |
0f113f3e | 140 | { |
5584f65a | 141 | BIGNUM *prk = BN_new(); |
46a64376 | 142 | |
5584f65a MC |
143 | if (prk == NULL) |
144 | goto err; | |
145 | BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME); | |
46a64376 | 146 | |
0f113f3e | 147 | if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont)) { |
a38c878c | 148 | BN_clear_free(prk); |
0f113f3e MC |
149 | goto err; |
150 | } | |
5584f65a | 151 | /* We MUST free prk before any further use of priv_key */ |
a38c878c | 152 | BN_clear_free(prk); |
0f113f3e | 153 | } |
46a64376 | 154 | |
0f113f3e MC |
155 | dh->pub_key = pub_key; |
156 | dh->priv_key = priv_key; | |
8b84b075 | 157 | dh->dirty_cnt++; |
0f113f3e MC |
158 | ok = 1; |
159 | err: | |
160 | if (ok != 1) | |
161 | DHerr(DH_F_GENERATE_KEY, ERR_R_BN_LIB); | |
d02b48c6 | 162 | |
23a1d5e9 | 163 | if (pub_key != dh->pub_key) |
0f113f3e | 164 | BN_free(pub_key); |
23a1d5e9 | 165 | if (priv_key != dh->priv_key) |
0f113f3e MC |
166 | BN_free(priv_key); |
167 | BN_CTX_free(ctx); | |
26a7d938 | 168 | return ok; |
0f113f3e | 169 | } |
d02b48c6 | 170 | |
f971ccb2 | 171 | static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh) |
0f113f3e MC |
172 | { |
173 | BN_CTX *ctx = NULL; | |
174 | BN_MONT_CTX *mont = NULL; | |
175 | BIGNUM *tmp; | |
176 | int ret = -1; | |
177 | int check_result; | |
d02b48c6 | 178 | |
0f113f3e MC |
179 | if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) { |
180 | DHerr(DH_F_COMPUTE_KEY, DH_R_MODULUS_TOO_LARGE); | |
181 | goto err; | |
182 | } | |
5e3225cc | 183 | |
0f113f3e MC |
184 | ctx = BN_CTX_new(); |
185 | if (ctx == NULL) | |
186 | goto err; | |
187 | BN_CTX_start(ctx); | |
188 | tmp = BN_CTX_get(ctx); | |
7928ee4d BE |
189 | if (tmp == NULL) |
190 | goto err; | |
6ec8e63a | 191 | |
0f113f3e MC |
192 | if (dh->priv_key == NULL) { |
193 | DHerr(DH_F_COMPUTE_KEY, DH_R_NO_PRIVATE_VALUE); | |
194 | goto err; | |
195 | } | |
dfeab068 | 196 | |
0f113f3e MC |
197 | if (dh->flags & DH_FLAG_CACHE_MONT_P) { |
198 | mont = BN_MONT_CTX_set_locked(&dh->method_mont_p, | |
d188a536 | 199 | dh->lock, dh->p, ctx); |
5584f65a | 200 | BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME); |
0f113f3e MC |
201 | if (!mont) |
202 | goto err; | |
203 | } | |
bf3d6c0c | 204 | |
0f113f3e MC |
205 | if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result) { |
206 | DHerr(DH_F_COMPUTE_KEY, DH_R_INVALID_PUBKEY); | |
207 | goto err; | |
208 | } | |
d02b48c6 | 209 | |
0f113f3e MC |
210 | if (!dh-> |
211 | meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key, dh->p, ctx, mont)) { | |
212 | DHerr(DH_F_COMPUTE_KEY, ERR_R_BN_LIB); | |
213 | goto err; | |
214 | } | |
13066cee | 215 | |
0f113f3e MC |
216 | ret = BN_bn2bin(tmp, key); |
217 | err: | |
ce1415ed SL |
218 | BN_CTX_end(ctx); |
219 | BN_CTX_free(ctx); | |
26a7d938 | 220 | return ret; |
0f113f3e | 221 | } |
6dad7bd6 | 222 | |
0f113f3e MC |
223 | static int dh_bn_mod_exp(const DH *dh, BIGNUM *r, |
224 | const BIGNUM *a, const BIGNUM *p, | |
225 | const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx) | |
226 | { | |
5584f65a | 227 | return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx); |
0f113f3e | 228 | } |
13066cee DSH |
229 | |
230 | static int dh_init(DH *dh) | |
0f113f3e MC |
231 | { |
232 | dh->flags |= DH_FLAG_CACHE_MONT_P; | |
208fb891 | 233 | return 1; |
0f113f3e | 234 | } |
13066cee DSH |
235 | |
236 | static int dh_finish(DH *dh) | |
0f113f3e | 237 | { |
23a1d5e9 | 238 | BN_MONT_CTX_free(dh->method_mont_p); |
208fb891 | 239 | return 1; |
0f113f3e | 240 | } |
9aaecbfc | 241 | |
242 | int dh_buf2key(DH *dh, const unsigned char *buf, size_t len) | |
243 | { | |
244 | int err_reason = DH_R_BN_ERROR; | |
245 | BIGNUM *pubkey = NULL; | |
246 | const BIGNUM *p; | |
247 | size_t p_size; | |
248 | ||
249 | if ((pubkey = BN_bin2bn(buf, len, NULL)) == NULL) | |
250 | goto err; | |
251 | DH_get0_pqg(dh, &p, NULL, NULL); | |
252 | if (p == NULL || (p_size = BN_num_bytes(p)) == 0) { | |
253 | err_reason = DH_R_NO_PARAMETERS_SET; | |
254 | goto err; | |
255 | } | |
256 | /* | |
257 | * As per Section 4.2.8.1 of RFC 8446 fail if DHE's | |
258 | * public key is of size not equal to size of p | |
259 | */ | |
260 | if (BN_is_zero(pubkey) || p_size != len) { | |
261 | err_reason = DH_R_INVALID_PUBKEY; | |
262 | goto err; | |
263 | } | |
264 | if (DH_set0_key(dh, pubkey, NULL) != 1) | |
265 | goto err; | |
266 | return 1; | |
267 | err: | |
268 | DHerr(DH_F_DH_BUF2KEY, err_reason); | |
269 | BN_free(pubkey); | |
270 | return 0; | |
271 | } | |
272 | ||
273 | size_t dh_key2buf(const DH *dh, unsigned char **pbuf_out) | |
274 | { | |
275 | const BIGNUM *pubkey; | |
276 | unsigned char *pbuf; | |
277 | const BIGNUM *p; | |
278 | int p_size; | |
279 | ||
280 | DH_get0_pqg(dh, &p, NULL, NULL); | |
281 | DH_get0_key(dh, &pubkey, NULL); | |
282 | if (p == NULL || pubkey == NULL | |
283 | || (p_size = BN_num_bytes(p)) == 0 | |
284 | || BN_num_bytes(pubkey) == 0) { | |
285 | DHerr(DH_F_DH_KEY2BUF, DH_R_INVALID_PUBKEY); | |
286 | return 0; | |
287 | } | |
288 | if ((pbuf = OPENSSL_malloc(p_size)) == NULL) { | |
289 | DHerr(DH_F_DH_KEY2BUF, ERR_R_MALLOC_FAILURE); | |
290 | return 0; | |
291 | } | |
292 | /* | |
293 | * As per Section 4.2.8.1 of RFC 8446 left pad public | |
294 | * key with zeros to the size of p | |
295 | */ | |
296 | if (BN_bn2binpad(pubkey, pbuf, p_size) < 0) { | |
297 | OPENSSL_free(pbuf); | |
298 | DHerr(DH_F_DH_KEY2BUF, DH_R_BN_ERROR); | |
299 | return 0; | |
300 | } | |
301 | *pbuf_out = pbuf; | |
302 | return p_size; | |
303 | } |