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comparison: security/nss/lib/freebl/dh.c

security/nss/lib/freebl/dh.c

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1 /* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
4
5 /*
6 * Diffie-Hellman parameter generation, key generation, and secret derivation.
7 * KEA secret generation and verification.
8 */
9 #ifdef FREEBL_NO_DEPEND
10 #include "stubs.h"
11 #endif
12
13 #include "prerr.h"
14 #include "secerr.h"
15
16 #include "blapi.h"
17 #include "secitem.h"
18 #include "mpi.h"
19 #include "mpprime.h"
20 #include "secmpi.h"
21
22 #define KEA_DERIVED_SECRET_LEN 128
23
24 /* Lengths are in bytes. */
25 static unsigned int
26 dh_GetSecretKeyLen(unsigned int primeLen)
27 {
28 /* Based on Table 2 in NIST SP 800-57. */
29 if (primeLen >= 1920) { /* 15360 bits */
30 return 64; /* 512 bits */
31 }
32 if (primeLen >= 960) { /* 7680 bits */
33 return 48; /* 384 bits */
34 }
35 if (primeLen >= 384) { /* 3072 bits */
36 return 32; /* 256 bits */
37 }
38 if (primeLen >= 256) { /* 2048 bits */
39 return 28; /* 224 bits */
40 }
41 return 20; /* 160 bits */
42 }
43
44 SECStatus
45 DH_GenParam(int primeLen, DHParams **params)
46 {
47 PLArenaPool *arena;
48 DHParams *dhparams;
49 unsigned char *pb = NULL;
50 unsigned char *ab = NULL;
51 unsigned long counter = 0;
52 mp_int p, q, a, h, psub1, test;
53 mp_err err = MP_OKAY;
54 SECStatus rv = SECSuccess;
55 if (!params || primeLen < 0) {
56 PORT_SetError(SEC_ERROR_INVALID_ARGS);
57 return SECFailure;
58 }
59 arena = PORT_NewArena(NSS_FREEBL_DEFAULT_CHUNKSIZE);
60 if (!arena) {
61 PORT_SetError(SEC_ERROR_NO_MEMORY);
62 return SECFailure;
63 }
64 dhparams = (DHParams *)PORT_ArenaZAlloc(arena, sizeof(DHParams));
65 if (!dhparams) {
66 PORT_SetError(SEC_ERROR_NO_MEMORY);
67 PORT_FreeArena(arena, PR_TRUE);
68 return SECFailure;
69 }
70 dhparams->arena = arena;
71 MP_DIGITS(&p) = 0;
72 MP_DIGITS(&q) = 0;
73 MP_DIGITS(&a) = 0;
74 MP_DIGITS(&h) = 0;
75 MP_DIGITS(&psub1) = 0;
76 MP_DIGITS(&test) = 0;
77 CHECK_MPI_OK( mp_init(&p) );
78 CHECK_MPI_OK( mp_init(&q) );
79 CHECK_MPI_OK( mp_init(&a) );
80 CHECK_MPI_OK( mp_init(&h) );
81 CHECK_MPI_OK( mp_init(&psub1) );
82 CHECK_MPI_OK( mp_init(&test) );
83 /* generate prime with MPI, uses Miller-Rabin to generate strong prime. */
84 pb = PORT_Alloc(primeLen);
85 CHECK_SEC_OK( RNG_GenerateGlobalRandomBytes(pb, primeLen) );
86 pb[0] |= 0x80; /* set high-order bit */
87 pb[primeLen-1] |= 0x01; /* set low-order bit */
88 CHECK_MPI_OK( mp_read_unsigned_octets(&p, pb, primeLen) );
89 CHECK_MPI_OK( mpp_make_prime(&p, primeLen * 8, PR_TRUE, &counter) );
90 /* construct Sophie-Germain prime q = (p-1)/2. */
91 CHECK_MPI_OK( mp_sub_d(&p, 1, &psub1) );
92 CHECK_MPI_OK( mp_div_2(&psub1, &q) );
93 /* construct a generator from the prime. */
94 ab = PORT_Alloc(primeLen);
95 /* generate a candidate number a in p's field */
96 CHECK_SEC_OK( RNG_GenerateGlobalRandomBytes(ab, primeLen) );
97 CHECK_MPI_OK( mp_read_unsigned_octets(&a, ab, primeLen) );
98 /* force a < p (note that quot(a/p) <= 1) */
99 if ( mp_cmp(&a, &p) > 0 )
100 CHECK_MPI_OK( mp_sub(&a, &p, &a) );
101 do {
102 /* check that a is in the range [2..p-1] */
103 if ( mp_cmp_d(&a, 2) < 0 || mp_cmp(&a, &psub1) >= 0) {
104 /* a is outside of the allowed range. Set a=3 and keep going. */
105 mp_set(&a, 3);
106 }
107 /* if a**q mod p != 1 then a is a generator */
108 CHECK_MPI_OK( mp_exptmod(&a, &q, &p, &test) );
109 if ( mp_cmp_d(&test, 1) != 0 )
110 break;
111 /* increment the candidate and try again. */
112 CHECK_MPI_OK( mp_add_d(&a, 1, &a) );
113 } while (PR_TRUE);
114 MPINT_TO_SECITEM(&p, &dhparams->prime, arena);
115 MPINT_TO_SECITEM(&a, &dhparams->base, arena);
116 *params = dhparams;
117 cleanup:
118 mp_clear(&p);
119 mp_clear(&q);
120 mp_clear(&a);
121 mp_clear(&h);
122 mp_clear(&psub1);
123 mp_clear(&test);
124 if (pb) PORT_ZFree(pb, primeLen);
125 if (ab) PORT_ZFree(ab, primeLen);
126 if (err) {
127 MP_TO_SEC_ERROR(err);
128 rv = SECFailure;
129 }
130 if (rv)
131 PORT_FreeArena(arena, PR_TRUE);
132 return rv;
133 }
134
135 SECStatus
136 DH_NewKey(DHParams *params, DHPrivateKey **privKey)
137 {
138 PLArenaPool *arena;
139 DHPrivateKey *key;
140 mp_int g, xa, p, Ya;
141 mp_err err = MP_OKAY;
142 SECStatus rv = SECSuccess;
143 if (!params || !privKey) {
144 PORT_SetError(SEC_ERROR_INVALID_ARGS);
145 return SECFailure;
146 }
147 arena = PORT_NewArena(NSS_FREEBL_DEFAULT_CHUNKSIZE);
148 if (!arena) {
149 PORT_SetError(SEC_ERROR_NO_MEMORY);
150 return SECFailure;
151 }
152 key = (DHPrivateKey *)PORT_ArenaZAlloc(arena, sizeof(DHPrivateKey));
153 if (!key) {
154 PORT_SetError(SEC_ERROR_NO_MEMORY);
155 PORT_FreeArena(arena, PR_TRUE);
156 return SECFailure;
157 }
158 key->arena = arena;
159 MP_DIGITS(&g) = 0;
160 MP_DIGITS(&xa) = 0;
161 MP_DIGITS(&p) = 0;
162 MP_DIGITS(&Ya) = 0;
163 CHECK_MPI_OK( mp_init(&g) );
164 CHECK_MPI_OK( mp_init(&xa) );
165 CHECK_MPI_OK( mp_init(&p) );
166 CHECK_MPI_OK( mp_init(&Ya) );
167 /* Set private key's p */
168 CHECK_SEC_OK( SECITEM_CopyItem(arena, &key->prime, &params->prime) );
169 SECITEM_TO_MPINT(key->prime, &p);
170 /* Set private key's g */
171 CHECK_SEC_OK( SECITEM_CopyItem(arena, &key->base, &params->base) );
172 SECITEM_TO_MPINT(key->base, &g);
173 /* Generate private key xa */
174 SECITEM_AllocItem(arena, &key->privateValue,
175 dh_GetSecretKeyLen(params->prime.len));
176 RNG_GenerateGlobalRandomBytes(key->privateValue.data,
177 key->privateValue.len);
178 SECITEM_TO_MPINT( key->privateValue, &xa );
179 /* xa < p */
180 CHECK_MPI_OK( mp_mod(&xa, &p, &xa) );
181 /* Compute public key Ya = g ** xa mod p */
182 CHECK_MPI_OK( mp_exptmod(&g, &xa, &p, &Ya) );
183 MPINT_TO_SECITEM(&Ya, &key->publicValue, key->arena);
184 *privKey = key;
185 cleanup:
186 mp_clear(&g);
187 mp_clear(&xa);
188 mp_clear(&p);
189 mp_clear(&Ya);
190 if (err) {
191 MP_TO_SEC_ERROR(err);
192 rv = SECFailure;
193 }
194 if (rv)
195 PORT_FreeArena(arena, PR_TRUE);
196 return rv;
197 }
198
199 SECStatus
200 DH_Derive(SECItem *publicValue,
201 SECItem *prime,
202 SECItem *privateValue,
203 SECItem *derivedSecret,
204 unsigned int outBytes)
205 {
206 mp_int p, Xa, Yb, ZZ, psub1;
207 mp_err err = MP_OKAY;
208 int len = 0;
209 unsigned int nb;
210 unsigned char *secret = NULL;
211 if (!publicValue || !prime || !privateValue || !derivedSecret) {
212 PORT_SetError(SEC_ERROR_INVALID_ARGS);
213 return SECFailure;
214 }
215 memset(derivedSecret, 0, sizeof *derivedSecret);
216 MP_DIGITS(&p) = 0;
217 MP_DIGITS(&Xa) = 0;
218 MP_DIGITS(&Yb) = 0;
219 MP_DIGITS(&ZZ) = 0;
220 MP_DIGITS(&psub1) = 0;
221 CHECK_MPI_OK( mp_init(&p) );
222 CHECK_MPI_OK( mp_init(&Xa) );
223 CHECK_MPI_OK( mp_init(&Yb) );
224 CHECK_MPI_OK( mp_init(&ZZ) );
225 CHECK_MPI_OK( mp_init(&psub1) );
226 SECITEM_TO_MPINT(*publicValue, &Yb);
227 SECITEM_TO_MPINT(*privateValue, &Xa);
228 SECITEM_TO_MPINT(*prime, &p);
229 CHECK_MPI_OK( mp_sub_d(&p, 1, &psub1) );
230
231 /* We assume that the modulus, p, is a safe prime. That is, p = 2q+1 where
232 * q is also a prime. Thus the orders of the subgroups are factors of 2q:
233 * namely 1, 2, q and 2q.
234 *
235 * We check that the peer's public value isn't zero (which isn't in the
236 * group), one (subgroup of order one) or p-1 (subgroup of order 2). We
237 * also check that the public value is less than p, to avoid being fooled
238 * by values like p+1 or 2*p-1.
239 *
240 * Thus we must be operating in the subgroup of size q or 2q. */
241 if (mp_cmp_d(&Yb, 1) <= 0 ||
242 mp_cmp(&Yb, &psub1) >= 0) {
243 err = MP_BADARG;
244 goto cleanup;
245 }
246
247 /* ZZ = (Yb)**Xa mod p */
248 CHECK_MPI_OK( mp_exptmod(&Yb, &Xa, &p, &ZZ) );
249 /* number of bytes in the derived secret */
250 len = mp_unsigned_octet_size(&ZZ);
251 if (len <= 0) {
252 err = MP_BADARG;
253 goto cleanup;
254 }
255 /* allocate a buffer which can hold the entire derived secret. */
256 secret = PORT_Alloc(len);
257 /* grab the derived secret */
258 err = mp_to_unsigned_octets(&ZZ, secret, len);
259 if (err >= 0) err = MP_OKAY;
260 /*
261 ** if outBytes is 0 take all of the bytes from the derived secret.
262 ** if outBytes is not 0 take exactly outBytes from the derived secret, zero
263 ** pad at the beginning if necessary, and truncate beginning bytes
264 ** if necessary.
265 */
266 if (outBytes > 0)
267 nb = outBytes;
268 else
269 nb = len;
270 SECITEM_AllocItem(NULL, derivedSecret, nb);
271 if (len < nb) {
272 unsigned int offset = nb - len;
273 memset(derivedSecret->data, 0, offset);
274 memcpy(derivedSecret->data + offset, secret, len);
275 } else {
276 memcpy(derivedSecret->data, secret + len - nb, nb);
277 }
278 cleanup:
279 mp_clear(&p);
280 mp_clear(&Xa);
281 mp_clear(&Yb);
282 mp_clear(&ZZ);
283 mp_clear(&psub1);
284 if (secret) {
285 /* free the buffer allocated for the full secret. */
286 PORT_ZFree(secret, len);
287 }
288 if (err) {
289 MP_TO_SEC_ERROR(err);
290 if (derivedSecret->data)
291 PORT_ZFree(derivedSecret->data, derivedSecret->len);
292 return SECFailure;
293 }
294 return SECSuccess;
295 }
296
297 SECStatus
298 KEA_Derive(SECItem *prime,
299 SECItem *public1,
300 SECItem *public2,
301 SECItem *private1,
302 SECItem *private2,
303 SECItem *derivedSecret)
304 {
305 mp_int p, Y, R, r, x, t, u, w;
306 mp_err err;
307 unsigned char *secret = NULL;
308 unsigned int len = 0, offset;
309 if (!prime || !public1 || !public2 || !private1 || !private2 ||
310 !derivedSecret) {
311 PORT_SetError(SEC_ERROR_INVALID_ARGS);
312 return SECFailure;
313 }
314 memset(derivedSecret, 0, sizeof *derivedSecret);
315 MP_DIGITS(&p) = 0;
316 MP_DIGITS(&Y) = 0;
317 MP_DIGITS(&R) = 0;
318 MP_DIGITS(&r) = 0;
319 MP_DIGITS(&x) = 0;
320 MP_DIGITS(&t) = 0;
321 MP_DIGITS(&u) = 0;
322 MP_DIGITS(&w) = 0;
323 CHECK_MPI_OK( mp_init(&p) );
324 CHECK_MPI_OK( mp_init(&Y) );
325 CHECK_MPI_OK( mp_init(&R) );
326 CHECK_MPI_OK( mp_init(&r) );
327 CHECK_MPI_OK( mp_init(&x) );
328 CHECK_MPI_OK( mp_init(&t) );
329 CHECK_MPI_OK( mp_init(&u) );
330 CHECK_MPI_OK( mp_init(&w) );
331 SECITEM_TO_MPINT(*prime, &p);
332 SECITEM_TO_MPINT(*public1, &Y);
333 SECITEM_TO_MPINT(*public2, &R);
334 SECITEM_TO_MPINT(*private1, &r);
335 SECITEM_TO_MPINT(*private2, &x);
336 /* t = DH(Y, r, p) = Y ** r mod p */
337 CHECK_MPI_OK( mp_exptmod(&Y, &r, &p, &t) );
338 /* u = DH(R, x, p) = R ** x mod p */
339 CHECK_MPI_OK( mp_exptmod(&R, &x, &p, &u) );
340 /* w = (t + u) mod p */
341 CHECK_MPI_OK( mp_addmod(&t, &u, &p, &w) );
342 /* allocate a buffer for the full derived secret */
343 len = mp_unsigned_octet_size(&w);
344 secret = PORT_Alloc(len);
345 /* grab the secret */
346 err = mp_to_unsigned_octets(&w, secret, len);
347 if (err > 0) err = MP_OKAY;
348 /* allocate output buffer */
349 SECITEM_AllocItem(NULL, derivedSecret, KEA_DERIVED_SECRET_LEN);
350 memset(derivedSecret->data, 0, derivedSecret->len);
351 /* copy in the 128 lsb of the secret */
352 if (len >= KEA_DERIVED_SECRET_LEN) {
353 memcpy(derivedSecret->data, secret + (len - KEA_DERIVED_SECRET_LEN),
354 KEA_DERIVED_SECRET_LEN);
355 } else {
356 offset = KEA_DERIVED_SECRET_LEN - len;
357 memcpy(derivedSecret->data + offset, secret, len);
358 }
359 cleanup:
360 mp_clear(&p);
361 mp_clear(&Y);
362 mp_clear(&R);
363 mp_clear(&r);
364 mp_clear(&x);
365 mp_clear(&t);
366 mp_clear(&u);
367 mp_clear(&w);
368 if (secret)
369 PORT_ZFree(secret, len);
370 if (err) {
371 MP_TO_SEC_ERROR(err);
372 return SECFailure;
373 }
374 return SECSuccess;
375 }
376
377 PRBool
378 KEA_Verify(SECItem *Y, SECItem *prime, SECItem *subPrime)
379 {
380 mp_int p, q, y, r;
381 mp_err err;
382 int cmp = 1; /* default is false */
383 if (!Y || !prime || !subPrime) {
384 PORT_SetError(SEC_ERROR_INVALID_ARGS);
385 return SECFailure;
386 }
387 MP_DIGITS(&p) = 0;
388 MP_DIGITS(&q) = 0;
389 MP_DIGITS(&y) = 0;
390 MP_DIGITS(&r) = 0;
391 CHECK_MPI_OK( mp_init(&p) );
392 CHECK_MPI_OK( mp_init(&q) );
393 CHECK_MPI_OK( mp_init(&y) );
394 CHECK_MPI_OK( mp_init(&r) );
395 SECITEM_TO_MPINT(*prime, &p);
396 SECITEM_TO_MPINT(*subPrime, &q);
397 SECITEM_TO_MPINT(*Y, &y);
398 /* compute r = y**q mod p */
399 CHECK_MPI_OK( mp_exptmod(&y, &q, &p, &r) );
400 /* compare to 1 */
401 cmp = mp_cmp_d(&r, 1);
402 cleanup:
403 mp_clear(&p);
404 mp_clear(&q);
405 mp_clear(&y);
406 mp_clear(&r);
407 if (err) {
408 MP_TO_SEC_ERROR(err);
409 return PR_FALSE;
410 }
411 return (cmp == 0) ? PR_TRUE : PR_FALSE;
412 }

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