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59f3477b DSH |
1 | /* crypto/dsa/dsa_ossl.c */ |
2 | /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) | |
3 | * All rights reserved. | |
4 | * | |
5 | * This package is an SSL implementation written | |
6 | * by Eric Young (eay@cryptsoft.com). | |
7 | * The implementation was written so as to conform with Netscapes SSL. | |
40720ce3 | 8 | * |
59f3477b DSH |
9 | * This library is free for commercial and non-commercial use as long as |
10 | * the following conditions are aheared to. The following conditions | |
11 | * apply to all code found in this distribution, be it the RC4, RSA, | |
12 | * lhash, DES, etc., code; not just the SSL code. The SSL documentation | |
13 | * included with this distribution is covered by the same copyright terms | |
14 | * except that the holder is Tim Hudson (tjh@cryptsoft.com). | |
40720ce3 | 15 | * |
59f3477b DSH |
16 | * Copyright remains Eric Young's, and as such any Copyright notices in |
17 | * the code are not to be removed. | |
18 | * If this package is used in a product, Eric Young should be given attribution | |
19 | * as the author of the parts of the library used. | |
20 | * This can be in the form of a textual message at program startup or | |
21 | * in documentation (online or textual) provided with the package. | |
40720ce3 | 22 | * |
59f3477b DSH |
23 | * Redistribution and use in source and binary forms, with or without |
24 | * modification, are permitted provided that the following conditions | |
25 | * are met: | |
26 | * 1. Redistributions of source code must retain the copyright | |
27 | * notice, this list of conditions and the following disclaimer. | |
28 | * 2. Redistributions in binary form must reproduce the above copyright | |
29 | * notice, this list of conditions and the following disclaimer in the | |
30 | * documentation and/or other materials provided with the distribution. | |
31 | * 3. All advertising materials mentioning features or use of this software | |
32 | * must display the following acknowledgement: | |
33 | * "This product includes cryptographic software written by | |
34 | * Eric Young (eay@cryptsoft.com)" | |
35 | * The word 'cryptographic' can be left out if the rouines from the library | |
36 | * being used are not cryptographic related :-). | |
40720ce3 | 37 | * 4. If you include any Windows specific code (or a derivative thereof) from |
59f3477b DSH |
38 | * the apps directory (application code) you must include an acknowledgement: |
39 | * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" | |
40720ce3 | 40 | * |
59f3477b DSH |
41 | * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND |
42 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
43 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
44 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE | |
45 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
46 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
47 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
48 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
49 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
50 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
51 | * SUCH DAMAGE. | |
40720ce3 | 52 | * |
59f3477b DSH |
53 | * The licence and distribution terms for any publically available version or |
54 | * derivative of this code cannot be changed. i.e. this code cannot simply be | |
55 | * copied and put under another distribution licence | |
56 | * [including the GNU Public Licence.] | |
57 | */ | |
58 | ||
59 | /* Original version from Steven Schoch <schoch@sheba.arc.nasa.gov> */ | |
60 | ||
61 | #include <stdio.h> | |
62 | #include <openssl/bn.h> | |
63 | #include <openssl/dsa.h> | |
64 | #include <openssl/rand.h> | |
65 | #include <openssl/asn1.h> | |
155ad6d2 | 66 | #include <openssl/err.h> |
59f3477b | 67 | #ifndef OPENSSL_NO_ENGINE |
40720ce3 | 68 | # include <openssl/engine.h> |
59f3477b DSH |
69 | #endif |
70 | #include <openssl/fips.h> | |
71 | ||
72 | #ifdef OPENSSL_FIPS | |
73 | ||
40720ce3 MC |
74 | static DSA_SIG *dsa_do_sign(const unsigned char *dgst, FIPS_DSA_SIZE_T dlen, |
75 | DSA *dsa); | |
76 | static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, | |
77 | BIGNUM **rp); | |
78 | static int dsa_do_verify(const unsigned char *dgst, FIPS_DSA_SIZE_T dgst_len, | |
79 | DSA_SIG *sig, DSA *dsa); | |
59f3477b DSH |
80 | static int dsa_init(DSA *dsa); |
81 | static int dsa_finish(DSA *dsa); | |
82 | static int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1, | |
40720ce3 MC |
83 | BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx, |
84 | BN_MONT_CTX *in_mont); | |
59f3477b | 85 | static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p, |
40720ce3 | 86 | const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx); |
59f3477b DSH |
87 | |
88 | static const DSA_METHOD openssl_dsa_meth = { | |
40720ce3 MC |
89 | "OpenSSL FIPS DSA method", |
90 | dsa_do_sign, | |
91 | dsa_sign_setup, | |
92 | dsa_do_verify, | |
93 | dsa_mod_exp, | |
94 | dsa_bn_mod_exp, | |
95 | dsa_init, | |
96 | dsa_finish, | |
97 | DSA_FLAG_FIPS_METHOD, | |
98 | NULL | |
59f3477b | 99 | }; |
40720ce3 MC |
100 | |
101 | # if 0 | |
59f3477b | 102 | int FIPS_dsa_check(struct dsa_st *dsa) |
40720ce3 MC |
103 | { |
104 | if (dsa->meth != &openssl_dsa_meth | |
105 | || dsa->meth->dsa_do_sign != dsa_do_sign | |
106 | || dsa->meth->dsa_sign_setup != dsa_sign_setup | |
107 | || dsa->meth->dsa_mod_exp != dsa_mod_exp | |
108 | || dsa->meth->bn_mod_exp != dsa_bn_mod_exp | |
109 | || dsa->meth->init != dsa_init || dsa->meth->finish != dsa_finish) { | |
110 | FIPSerr(FIPS_F_FIPS_DSA_CHECK, FIPS_R_NON_FIPS_METHOD); | |
111 | return 0; | |
59f3477b | 112 | } |
40720ce3 MC |
113 | return 1; |
114 | } | |
115 | # endif | |
59f3477b DSH |
116 | |
117 | const DSA_METHOD *DSA_OpenSSL(void) | |
118 | { | |
40720ce3 | 119 | return &openssl_dsa_meth; |
59f3477b DSH |
120 | } |
121 | ||
40720ce3 MC |
122 | static DSA_SIG *dsa_do_sign(const unsigned char *dgst, FIPS_DSA_SIZE_T dlen, |
123 | DSA *dsa) | |
124 | { | |
125 | BIGNUM *kinv = NULL, *r = NULL, *s = NULL; | |
126 | BIGNUM m; | |
127 | BIGNUM xr; | |
128 | BN_CTX *ctx = NULL; | |
129 | int i, reason = ERR_R_BN_LIB; | |
130 | DSA_SIG *ret = NULL; | |
131 | ||
132 | if (FIPS_selftest_failed()) { | |
133 | FIPSerr(FIPS_F_DSA_DO_SIGN, FIPS_R_FIPS_SELFTEST_FAILED); | |
134 | return NULL; | |
135 | } | |
136 | ||
137 | if (FIPS_mode() | |
138 | && (BN_num_bits(dsa->p) < OPENSSL_DSA_FIPS_MIN_MODULUS_BITS)) { | |
139 | DSAerr(DSA_F_DSA_DO_SIGN, DSA_R_KEY_SIZE_TOO_SMALL); | |
140 | return NULL; | |
141 | } | |
142 | ||
143 | BN_init(&m); | |
144 | BN_init(&xr); | |
145 | ||
146 | if (!dsa->p || !dsa->q || !dsa->g) { | |
147 | reason = DSA_R_MISSING_PARAMETERS; | |
148 | goto err; | |
149 | } | |
150 | ||
151 | s = BN_new(); | |
152 | if (s == NULL) | |
153 | goto err; | |
154 | ||
155 | i = BN_num_bytes(dsa->q); /* should be 20 */ | |
156 | if ((dlen > i) || (dlen > 50)) { | |
157 | reason = DSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE; | |
158 | goto err; | |
159 | } | |
160 | ||
161 | ctx = BN_CTX_new(); | |
162 | if (ctx == NULL) | |
163 | goto err; | |
164 | ||
165 | if (!dsa->meth->dsa_sign_setup(dsa, ctx, &kinv, &r)) | |
166 | goto err; | |
167 | ||
168 | if (BN_bin2bn(dgst, dlen, &m) == NULL) | |
169 | goto err; | |
170 | ||
171 | /* Compute s = inv(k) (m + xr) mod q */ | |
172 | if (!BN_mod_mul(&xr, dsa->priv_key, r, dsa->q, ctx)) | |
173 | goto err; /* s = xr */ | |
174 | if (!BN_add(s, &xr, &m)) | |
175 | goto err; /* s = m + xr */ | |
176 | if (BN_cmp(s, dsa->q) > 0) | |
177 | BN_sub(s, s, dsa->q); | |
178 | if (!BN_mod_mul(s, s, kinv, dsa->q, ctx)) | |
179 | goto err; | |
180 | ||
181 | ret = DSA_SIG_new(); | |
182 | if (ret == NULL) | |
183 | goto err; | |
184 | ret->r = r; | |
185 | ret->s = s; | |
186 | ||
187 | err: | |
188 | if (!ret) { | |
189 | DSAerr(DSA_F_DSA_DO_SIGN, reason); | |
190 | BN_free(r); | |
191 | BN_free(s); | |
192 | } | |
193 | if (ctx != NULL) | |
194 | BN_CTX_free(ctx); | |
195 | BN_clear_free(&m); | |
196 | BN_clear_free(&xr); | |
197 | if (kinv != NULL) /* dsa->kinv is NULL now if we used it */ | |
198 | BN_clear_free(kinv); | |
199 | return (ret); | |
200 | } | |
201 | ||
202 | static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, | |
203 | BIGNUM **rp) | |
204 | { | |
205 | BN_CTX *ctx; | |
206 | BIGNUM k, kq, *K, *kinv = NULL, *r = NULL; | |
207 | int ret = 0; | |
208 | ||
209 | if (!dsa->p || !dsa->q || !dsa->g) { | |
210 | DSAerr(DSA_F_DSA_SIGN_SETUP, DSA_R_MISSING_PARAMETERS); | |
211 | return 0; | |
212 | } | |
213 | ||
214 | BN_init(&k); | |
215 | BN_init(&kq); | |
216 | ||
217 | if (ctx_in == NULL) { | |
218 | if ((ctx = BN_CTX_new()) == NULL) | |
219 | goto err; | |
220 | } else | |
221 | ctx = ctx_in; | |
222 | ||
223 | if ((r = BN_new()) == NULL) | |
224 | goto err; | |
225 | ||
226 | /* Get random k */ | |
227 | do | |
228 | if (!BN_rand_range(&k, dsa->q)) | |
229 | goto err; | |
230 | while (BN_is_zero(&k)) ; | |
231 | if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) { | |
232 | BN_set_flags(&k, BN_FLG_CONSTTIME); | |
233 | } | |
234 | ||
235 | if (dsa->flags & DSA_FLAG_CACHE_MONT_P) { | |
236 | if (!BN_MONT_CTX_set_locked((BN_MONT_CTX **)&dsa->method_mont_p, | |
237 | CRYPTO_LOCK_DSA, dsa->p, ctx)) | |
238 | goto err; | |
239 | } | |
240 | ||
241 | /* Compute r = (g^k mod p) mod q */ | |
242 | ||
243 | if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) { | |
244 | if (!BN_copy(&kq, &k)) | |
245 | goto err; | |
246 | ||
247 | /* | |
248 | * We do not want timing information to leak the length of k, so we | |
249 | * compute g^k using an equivalent exponent of fixed length. (This | |
250 | * is a kludge that we need because the BN_mod_exp_mont() does not | |
251 | * let us specify the desired timing behaviour.) | |
252 | */ | |
253 | ||
254 | if (!BN_add(&kq, &kq, dsa->q)) | |
255 | goto err; | |
256 | if (BN_num_bits(&kq) <= BN_num_bits(dsa->q)) { | |
257 | if (!BN_add(&kq, &kq, dsa->q)) | |
258 | goto err; | |
259 | } | |
260 | ||
261 | K = &kq; | |
262 | } else { | |
263 | K = &k; | |
264 | } | |
265 | if (!dsa->meth->bn_mod_exp(dsa, r, dsa->g, K, dsa->p, ctx, | |
266 | (BN_MONT_CTX *)dsa->method_mont_p)) | |
267 | goto err; | |
268 | if (!BN_mod(r, r, dsa->q, ctx)) | |
269 | goto err; | |
270 | ||
271 | /* Compute part of 's = inv(k) (m + xr) mod q' */ | |
272 | if ((kinv = BN_mod_inverse(NULL, &k, dsa->q, ctx)) == NULL) | |
273 | goto err; | |
274 | ||
275 | if (*kinvp != NULL) | |
276 | BN_clear_free(*kinvp); | |
277 | *kinvp = kinv; | |
278 | kinv = NULL; | |
279 | if (*rp != NULL) | |
280 | BN_clear_free(*rp); | |
281 | *rp = r; | |
282 | ret = 1; | |
283 | err: | |
284 | if (!ret) { | |
285 | DSAerr(DSA_F_DSA_SIGN_SETUP, ERR_R_BN_LIB); | |
286 | if (kinv != NULL) | |
287 | BN_clear_free(kinv); | |
288 | if (r != NULL) | |
289 | BN_clear_free(r); | |
290 | } | |
291 | if (ctx_in == NULL) | |
292 | BN_CTX_free(ctx); | |
293 | if (kinv != NULL) | |
294 | BN_clear_free(kinv); | |
295 | BN_clear_free(&k); | |
296 | BN_clear_free(&kq); | |
297 | return (ret); | |
298 | } | |
299 | ||
300 | static int dsa_do_verify(const unsigned char *dgst, FIPS_DSA_SIZE_T dgst_len, | |
301 | DSA_SIG *sig, DSA *dsa) | |
302 | { | |
303 | BN_CTX *ctx; | |
304 | BIGNUM u1, u2, t1; | |
305 | BN_MONT_CTX *mont = NULL; | |
306 | int ret = -1; | |
307 | ||
308 | if (!dsa->p || !dsa->q || !dsa->g) { | |
309 | DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_MISSING_PARAMETERS); | |
310 | return -1; | |
311 | } | |
312 | ||
313 | if (FIPS_selftest_failed()) { | |
314 | FIPSerr(FIPS_F_DSA_DO_VERIFY, FIPS_R_FIPS_SELFTEST_FAILED); | |
315 | return -1; | |
316 | } | |
317 | ||
318 | if (BN_num_bits(dsa->q) != 160) { | |
319 | DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_BAD_Q_VALUE); | |
320 | return -1; | |
321 | } | |
322 | ||
323 | if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS) { | |
324 | DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_MODULUS_TOO_LARGE); | |
325 | return -1; | |
326 | } | |
327 | ||
328 | if (FIPS_mode() | |
329 | && (BN_num_bits(dsa->p) < OPENSSL_DSA_FIPS_MIN_MODULUS_BITS)) { | |
330 | DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_KEY_SIZE_TOO_SMALL); | |
331 | return -1; | |
332 | } | |
333 | ||
334 | BN_init(&u1); | |
335 | BN_init(&u2); | |
336 | BN_init(&t1); | |
337 | ||
338 | if ((ctx = BN_CTX_new()) == NULL) | |
339 | goto err; | |
340 | ||
341 | if (BN_is_zero(sig->r) || sig->r->neg || BN_ucmp(sig->r, dsa->q) >= 0) { | |
342 | ret = 0; | |
343 | goto err; | |
344 | } | |
345 | if (BN_is_zero(sig->s) || sig->s->neg || BN_ucmp(sig->s, dsa->q) >= 0) { | |
346 | ret = 0; | |
347 | goto err; | |
348 | } | |
349 | ||
350 | /* | |
351 | * Calculate W = inv(S) mod Q save W in u2 | |
352 | */ | |
353 | if ((BN_mod_inverse(&u2, sig->s, dsa->q, ctx)) == NULL) | |
354 | goto err; | |
355 | ||
356 | /* save M in u1 */ | |
357 | if (BN_bin2bn(dgst, dgst_len, &u1) == NULL) | |
358 | goto err; | |
359 | ||
360 | /* u1 = M * w mod q */ | |
361 | if (!BN_mod_mul(&u1, &u1, &u2, dsa->q, ctx)) | |
362 | goto err; | |
363 | ||
364 | /* u2 = r * w mod q */ | |
365 | if (!BN_mod_mul(&u2, sig->r, &u2, dsa->q, ctx)) | |
366 | goto err; | |
367 | ||
368 | if (dsa->flags & DSA_FLAG_CACHE_MONT_P) { | |
369 | mont = BN_MONT_CTX_set_locked((BN_MONT_CTX **)&dsa->method_mont_p, | |
370 | CRYPTO_LOCK_DSA, dsa->p, ctx); | |
371 | if (!mont) | |
372 | goto err; | |
373 | } | |
374 | # if 0 | |
375 | { | |
376 | BIGNUM t2; | |
377 | ||
378 | BN_init(&t2); | |
379 | /* v = ( g^u1 * y^u2 mod p ) mod q */ | |
380 | /* let t1 = g ^ u1 mod p */ | |
381 | if (!BN_mod_exp_mont(&t1, dsa->g, &u1, dsa->p, ctx, mont)) | |
382 | goto err; | |
383 | /* let t2 = y ^ u2 mod p */ | |
384 | if (!BN_mod_exp_mont(&t2, dsa->pub_key, &u2, dsa->p, ctx, mont)) | |
385 | goto err; | |
386 | /* let u1 = t1 * t2 mod p */ | |
387 | if (!BN_mod_mul(&u1, &t1, &t2, dsa->p, ctx)) | |
388 | goto err_bn; | |
389 | BN_free(&t2); | |
390 | } | |
391 | /* let u1 = u1 mod q */ | |
392 | if (!BN_mod(&u1, &u1, dsa->q, ctx)) | |
393 | goto err; | |
394 | # else | |
395 | { | |
396 | if (!dsa->meth->dsa_mod_exp(dsa, &t1, dsa->g, &u1, dsa->pub_key, &u2, | |
397 | dsa->p, ctx, mont)) | |
398 | goto err; | |
399 | /* BN_copy(&u1,&t1); */ | |
400 | /* let u1 = u1 mod q */ | |
401 | if (!BN_mod(&u1, &t1, dsa->q, ctx)) | |
402 | goto err; | |
403 | } | |
404 | # endif | |
405 | /* | |
406 | * V is now in u1. If the signature is correct, it will be equal to R. | |
407 | */ | |
408 | ret = (BN_ucmp(&u1, sig->r) == 0); | |
409 | ||
410 | err: | |
411 | if (ret != 1) | |
412 | DSAerr(DSA_F_DSA_DO_VERIFY, ERR_R_BN_LIB); | |
413 | if (ctx != NULL) | |
414 | BN_CTX_free(ctx); | |
415 | BN_free(&u1); | |
416 | BN_free(&u2); | |
417 | BN_free(&t1); | |
418 | return (ret); | |
419 | } | |
59f3477b DSH |
420 | |
421 | static int dsa_init(DSA *dsa) | |
422 | { | |
40720ce3 MC |
423 | FIPS_selftest_check(); |
424 | dsa->flags |= DSA_FLAG_CACHE_MONT_P; | |
425 | return (1); | |
59f3477b DSH |
426 | } |
427 | ||
428 | static int dsa_finish(DSA *dsa) | |
429 | { | |
40720ce3 MC |
430 | if (dsa->method_mont_p) |
431 | BN_MONT_CTX_free((BN_MONT_CTX *)dsa->method_mont_p); | |
432 | return (1); | |
59f3477b DSH |
433 | } |
434 | ||
435 | static int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1, | |
40720ce3 MC |
436 | BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx, |
437 | BN_MONT_CTX *in_mont) | |
59f3477b | 438 | { |
40720ce3 | 439 | return BN_mod_exp2_mont(rr, a1, p1, a2, p2, m, ctx, in_mont); |
59f3477b | 440 | } |
40720ce3 | 441 | |
59f3477b | 442 | static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p, |
40720ce3 | 443 | const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx) |
59f3477b | 444 | { |
40720ce3 | 445 | return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx); |
59f3477b DSH |
446 | } |
447 | ||
40720ce3 | 448 | #else /* ndef OPENSSL_FIPS */ |
59f3477b | 449 | |
40720ce3 | 450 | static void *dummy = &dummy; |
59f3477b | 451 | |
40720ce3 | 452 | #endif /* ndef OPENSSL_FIPS */ |