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diff --git a/src/lib/libcrypto/dsa/dsa_ossl.c b/src/lib/libcrypto/dsa/dsa_ossl.c
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1/* $OpenBSD: dsa_ossl.c,v 1.22 2014/10/18 17:20:40 jsing Exp $ */
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.
8 *
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).
15 *
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.
22 *
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 :-).
37 * 4. If you include any Windows specific code (or a derivative thereof) from
38 * the apps directory (application code) you must include an acknowledgement:
39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40 *
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.
52 *
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
63#include <openssl/asn1.h>
64#include <openssl/bn.h>
65#include <openssl/dsa.h>
66#include <openssl/err.h>
67#include <openssl/sha.h>
68
69static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
70static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
71 BIGNUM **rp);
72static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
73 DSA *dsa);
74static int dsa_init(DSA *dsa);
75static int dsa_finish(DSA *dsa);
76
77static DSA_METHOD openssl_dsa_meth = {
78 .name = "OpenSSL DSA method",
79 .dsa_do_sign = dsa_do_sign,
80 .dsa_sign_setup = dsa_sign_setup,
81 .dsa_do_verify = dsa_do_verify,
82 .init = dsa_init,
83 .finish = dsa_finish
84};
85
86/*
87 * These macro wrappers replace attempts to use the dsa_mod_exp() and
88 * bn_mod_exp() handlers in the DSA_METHOD structure. We avoid the problem of
89 * having a the macro work as an expression by bundling an "err_instr". So;
90 *
91 * if (!dsa->meth->bn_mod_exp(dsa, r,dsa->g,&k,dsa->p,ctx,
92 * dsa->method_mont_p)) goto err;
93 *
94 * can be replaced by;
95 *
96 * DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, &k, dsa->p, ctx,
97 * dsa->method_mont_p);
98 */
99
100#define DSA_MOD_EXP(err_instr,dsa,rr,a1,p1,a2,p2,m,ctx,in_mont) \
101do { \
102 int _tmp_res53; \
103 if ((dsa)->meth->dsa_mod_exp) \
104 _tmp_res53 = (dsa)->meth->dsa_mod_exp((dsa), (rr), \
105 (a1), (p1), (a2), (p2), (m), (ctx), (in_mont)); \
106 else \
107 _tmp_res53 = BN_mod_exp2_mont((rr), (a1), \
108 (p1), (a2), (p2), (m), (ctx), (in_mont)); \
109 if (!_tmp_res53) \
110 err_instr; \
111} while(0)
112
113#define DSA_BN_MOD_EXP(err_instr,dsa,r,a,p,m,ctx,m_ctx) \
114do { \
115 int _tmp_res53; \
116 if ((dsa)->meth->bn_mod_exp) \
117 _tmp_res53 = (dsa)->meth->bn_mod_exp((dsa), (r), \
118 (a), (p), (m), (ctx), (m_ctx)); \
119 else \
120 _tmp_res53 = BN_mod_exp_mont((r), (a), (p), (m), \
121 (ctx), (m_ctx)); \
122 if (!_tmp_res53) \
123 err_instr; \
124} while(0)
125
126const DSA_METHOD *
127DSA_OpenSSL(void)
128{
129 return &openssl_dsa_meth;
130}
131
132static DSA_SIG *
133dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
134{
135 BIGNUM *kinv = NULL, *r = NULL, *s = NULL;
136 BIGNUM m;
137 BIGNUM xr;
138 BN_CTX *ctx = NULL;
139 int reason = ERR_R_BN_LIB;
140 DSA_SIG *ret = NULL;
141 int noredo = 0;
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 ctx = BN_CTX_new();
155 if (ctx == NULL)
156 goto err;
157redo:
158 if (dsa->kinv == NULL || dsa->r == NULL) {
159 if (!DSA_sign_setup(dsa, ctx, &kinv, &r))
160 goto err;
161 } else {
162 kinv = dsa->kinv;
163 dsa->kinv = NULL;
164 r = dsa->r;
165 dsa->r = NULL;
166 noredo = 1;
167 }
168
169
170 /*
171 * If the digest length is greater than the size of q use the
172 * BN_num_bits(dsa->q) leftmost bits of the digest, see
173 * fips 186-3, 4.2
174 */
175 if (dlen > BN_num_bytes(dsa->q))
176 dlen = BN_num_bytes(dsa->q);
177 if (BN_bin2bn(dgst,dlen,&m) == NULL)
178 goto err;
179
180 /* Compute s = inv(k) (m + xr) mod q */
181 if (!BN_mod_mul(&xr, dsa->priv_key, r, dsa->q, ctx)) /* s = xr */
182 goto err;
183 if (!BN_add(s, &xr, &m)) /* s = m + xr */
184 goto err;
185 if (BN_cmp(s, dsa->q) > 0)
186 if (!BN_sub(s, s, dsa->q))
187 goto err;
188 if (!BN_mod_mul(s, s, kinv, dsa->q, ctx))
189 goto err;
190
191 ret = DSA_SIG_new();
192 if (ret == NULL)
193 goto err;
194 /*
195 * Redo if r or s is zero as required by FIPS 186-3: this is
196 * very unlikely.
197 */
198 if (BN_is_zero(r) || BN_is_zero(s)) {
199 if (noredo) {
200 reason = DSA_R_NEED_NEW_SETUP_VALUES;
201 goto err;
202 }
203 goto redo;
204 }
205 ret->r = r;
206 ret->s = s;
207
208err:
209 if (!ret) {
210 DSAerr(DSA_F_DSA_DO_SIGN, reason);
211 BN_free(r);
212 BN_free(s);
213 }
214 BN_CTX_free(ctx);
215 BN_clear_free(&m);
216 BN_clear_free(&xr);
217 BN_clear_free(kinv);
218 return ret;
219}
220
221static int
222dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
223{
224 BN_CTX *ctx;
225 BIGNUM k, kq, *K, *kinv = NULL, *r = NULL;
226 int ret = 0;
227
228 if (!dsa->p || !dsa->q || !dsa->g) {
229 DSAerr(DSA_F_DSA_SIGN_SETUP, DSA_R_MISSING_PARAMETERS);
230 return 0;
231 }
232
233 BN_init(&k);
234 BN_init(&kq);
235
236 if (ctx_in == NULL) {
237 if ((ctx = BN_CTX_new()) == NULL)
238 goto err;
239 } else
240 ctx = ctx_in;
241
242 if ((r = BN_new()) == NULL)
243 goto err;
244
245 /* Get random k */
246 do {
247 if (!BN_rand_range(&k, dsa->q))
248 goto err;
249 } while (BN_is_zero(&k));
250 if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) {
251 BN_set_flags(&k, BN_FLG_CONSTTIME);
252 }
253
254 if (dsa->flags & DSA_FLAG_CACHE_MONT_P) {
255 if (!BN_MONT_CTX_set_locked(&dsa->method_mont_p,
256 CRYPTO_LOCK_DSA, dsa->p, ctx))
257 goto err;
258 }
259
260 /* Compute r = (g^k mod p) mod q */
261
262 if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) {
263 if (!BN_copy(&kq, &k))
264 goto err;
265
266 /*
267 * We do not want timing information to leak the length of k,
268 * so we compute g^k using an equivalent exponent of fixed
269 * length.
270 *
271 * (This is a kludge that we need because the BN_mod_exp_mont()
272 * does not let us specify the desired timing behaviour.)
273 */
274
275 if (!BN_add(&kq, &kq, dsa->q))
276 goto err;
277 if (BN_num_bits(&kq) <= BN_num_bits(dsa->q)) {
278 if (!BN_add(&kq, &kq, dsa->q))
279 goto err;
280 }
281
282 K = &kq;
283 } else {
284 K = &k;
285 }
286 DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, K, dsa->p, ctx,
287 dsa->method_mont_p);
288 if (!BN_mod(r,r,dsa->q,ctx))
289 goto err;
290
291 /* Compute part of 's = inv(k) (m + xr) mod q' */
292 if ((kinv = BN_mod_inverse(NULL, &k, dsa->q, ctx)) == NULL)
293 goto err;
294
295 BN_clear_free(*kinvp);
296 *kinvp = kinv;
297 kinv = NULL;
298 BN_clear_free(*rp);
299 *rp = r;
300 ret = 1;
301err:
302 if (!ret) {
303 DSAerr(DSA_F_DSA_SIGN_SETUP, ERR_R_BN_LIB);
304 BN_clear_free(r);
305 }
306 if (ctx_in == NULL)
307 BN_CTX_free(ctx);
308 BN_clear_free(&k);
309 BN_clear_free(&kq);
310 return ret;
311}
312
313static int
314dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig, DSA *dsa)
315{
316 BN_CTX *ctx;
317 BIGNUM u1, u2, t1;
318 BN_MONT_CTX *mont = NULL;
319 int ret = -1, i;
320
321 if (!dsa->p || !dsa->q || !dsa->g) {
322 DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_MISSING_PARAMETERS);
323 return -1;
324 }
325
326 i = BN_num_bits(dsa->q);
327 /* fips 186-3 allows only different sizes for q */
328 if (i != 160 && i != 224 && i != 256) {
329 DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_BAD_Q_VALUE);
330 return -1;
331 }
332
333 if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS) {
334 DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_MODULUS_TOO_LARGE);
335 return -1;
336 }
337 BN_init(&u1);
338 BN_init(&u2);
339 BN_init(&t1);
340
341 if ((ctx = BN_CTX_new()) == NULL)
342 goto err;
343
344 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
345 BN_ucmp(sig->r, dsa->q) >= 0) {
346 ret = 0;
347 goto err;
348 }
349 if (BN_is_zero(sig->s) || BN_is_negative(sig->s) ||
350 BN_ucmp(sig->s, dsa->q) >= 0) {
351 ret = 0;
352 goto err;
353 }
354
355 /* Calculate W = inv(S) mod Q
356 * save W in u2 */
357 if ((BN_mod_inverse(&u2, sig->s, dsa->q, ctx)) == NULL)
358 goto err;
359
360 /* save M in u1 */
361 /*
362 * If the digest length is greater than the size of q use the
363 * BN_num_bits(dsa->q) leftmost bits of the digest, see
364 * fips 186-3, 4.2
365 */
366 if (dgst_len > (i >> 3))
367 dgst_len = (i >> 3);
368 if (BN_bin2bn(dgst, dgst_len, &u1) == NULL)
369 goto err;
370
371 /* u1 = M * w mod q */
372 if (!BN_mod_mul(&u1, &u1, &u2, dsa->q, ctx))
373 goto err;
374
375 /* u2 = r * w mod q */
376 if (!BN_mod_mul(&u2, sig->r, &u2, dsa->q, ctx))
377 goto err;
378
379
380 if (dsa->flags & DSA_FLAG_CACHE_MONT_P) {
381 mont = BN_MONT_CTX_set_locked(&dsa->method_mont_p,
382 CRYPTO_LOCK_DSA, dsa->p, ctx);
383 if (!mont)
384 goto err;
385 }
386
387 DSA_MOD_EXP(goto err, dsa, &t1, dsa->g, &u1, dsa->pub_key, &u2, dsa->p,
388 ctx, mont);
389 /* BN_copy(&u1,&t1); */
390 /* let u1 = u1 mod q */
391 if (!BN_mod(&u1, &t1, dsa->q, ctx))
392 goto err;
393
394 /* V is now in u1. If the signature is correct, it will be
395 * equal to R. */
396 ret = BN_ucmp(&u1, sig->r) == 0;
397
398err:
399 /* XXX: surely this is wrong - if ret is 0, it just didn't verify;
400 there is no error in BN. Test should be ret == -1 (Ben) */
401 if (ret != 1)
402 DSAerr(DSA_F_DSA_DO_VERIFY, ERR_R_BN_LIB);
403 BN_CTX_free(ctx);
404 BN_free(&u1);
405 BN_free(&u2);
406 BN_free(&t1);
407 return ret;
408}
409
410static int
411dsa_init(DSA *dsa)
412{
413 dsa->flags |= DSA_FLAG_CACHE_MONT_P;
414 return 1;
415}
416
417static int
418dsa_finish(DSA *dsa)
419{
420 BN_MONT_CTX_free(dsa->method_mont_p);
421 return 1;
422}
423
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