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c0711f7f 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 | * |
c0711f7f 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 | * |
c0711f7f 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 | * |
c0711f7f 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 |
c0711f7f 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 | * |
c0711f7f 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 | * |
c0711f7f 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 "cryptlib.h" | |
63 | #include <openssl/bn.h> | |
64 | #include <openssl/dsa.h> | |
65 | #include <openssl/rand.h> | |
66 | #include <openssl/asn1.h> | |
67 | ||
e3f2860e DSH |
68 | #ifndef OPENSSL_FIPS |
69 | ||
c0711f7f | 70 | static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa); |
40720ce3 MC |
71 | static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, |
72 | BIGNUM **rp); | |
73 | static int dsa_do_verify(const unsigned char *dgst, int dgst_len, | |
74 | DSA_SIG *sig, DSA *dsa); | |
c0711f7f DSH |
75 | static int dsa_init(DSA *dsa); |
76 | static int dsa_finish(DSA *dsa); | |
c0711f7f DSH |
77 | |
78 | static DSA_METHOD openssl_dsa_meth = { | |
40720ce3 MC |
79 | "OpenSSL DSA method", |
80 | dsa_do_sign, | |
81 | dsa_sign_setup, | |
82 | dsa_do_verify, | |
83 | NULL, /* dsa_mod_exp, */ | |
84 | NULL, /* dsa_bn_mod_exp, */ | |
85 | dsa_init, | |
86 | dsa_finish, | |
87 | 0, | |
88 | NULL, | |
89 | NULL, | |
90 | NULL | |
c0711f7f DSH |
91 | }; |
92 | ||
b558c8d5 TH |
93 | /*- |
94 | * These macro wrappers replace attempts to use the dsa_mod_exp() and | |
879650b8 GT |
95 | * bn_mod_exp() handlers in the DSA_METHOD structure. We avoid the problem of |
96 | * having a the macro work as an expression by bundling an "err_instr". So; | |
40720ce3 | 97 | * |
879650b8 GT |
98 | * if (!dsa->meth->bn_mod_exp(dsa, r,dsa->g,&k,dsa->p,ctx, |
99 | * dsa->method_mont_p)) goto err; | |
100 | * | |
101 | * can be replaced by; | |
102 | * | |
103 | * DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, &k, dsa->p, ctx, | |
104 | * dsa->method_mont_p); | |
105 | */ | |
106 | ||
40720ce3 MC |
107 | # define DSA_MOD_EXP(err_instr,dsa,rr,a1,p1,a2,p2,m,ctx,in_mont) \ |
108 | do { \ | |
109 | int _tmp_res53; \ | |
110 | if((dsa)->meth->dsa_mod_exp) \ | |
111 | _tmp_res53 = (dsa)->meth->dsa_mod_exp((dsa), (rr), (a1), (p1), \ | |
112 | (a2), (p2), (m), (ctx), (in_mont)); \ | |
113 | else \ | |
114 | _tmp_res53 = BN_mod_exp2_mont((rr), (a1), (p1), (a2), (p2), \ | |
115 | (m), (ctx), (in_mont)); \ | |
116 | if(!_tmp_res53) err_instr; \ | |
117 | } while(0) | |
118 | # define DSA_BN_MOD_EXP(err_instr,dsa,r,a,p,m,ctx,m_ctx) \ | |
119 | do { \ | |
120 | int _tmp_res53; \ | |
121 | if((dsa)->meth->bn_mod_exp) \ | |
122 | _tmp_res53 = (dsa)->meth->bn_mod_exp((dsa), (r), (a), (p), \ | |
123 | (m), (ctx), (m_ctx)); \ | |
124 | else \ | |
125 | _tmp_res53 = BN_mod_exp_mont((r), (a), (p), (m), (ctx), (m_ctx)); \ | |
126 | if(!_tmp_res53) err_instr; \ | |
127 | } while(0) | |
879650b8 | 128 | |
a4aba800 | 129 | const DSA_METHOD *DSA_OpenSSL(void) |
c0711f7f | 130 | { |
40720ce3 | 131 | return &openssl_dsa_meth; |
c0711f7f DSH |
132 | } |
133 | ||
134 | static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa) | |
40720ce3 MC |
135 | { |
136 | BIGNUM *kinv = NULL, *r = NULL, *s = NULL; | |
137 | BIGNUM m; | |
138 | BIGNUM xr; | |
139 | BN_CTX *ctx = NULL; | |
140 | int i, reason = ERR_R_BN_LIB; | |
141 | DSA_SIG *ret = NULL; | |
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->kinv == NULL) || (dsa->r == NULL)) { | |
166 | if (!DSA_sign_setup(dsa, ctx, &kinv, &r)) | |
167 | goto err; | |
168 | } else { | |
169 | kinv = dsa->kinv; | |
170 | dsa->kinv = NULL; | |
171 | r = dsa->r; | |
172 | dsa->r = NULL; | |
173 | } | |
174 | ||
175 | if (BN_bin2bn(dgst, dlen, &m) == NULL) | |
176 | goto err; | |
177 | ||
178 | /* Compute s = inv(k) (m + xr) mod q */ | |
179 | if (!BN_mod_mul(&xr, dsa->priv_key, r, dsa->q, ctx)) | |
180 | goto err; /* s = xr */ | |
181 | if (!BN_add(s, &xr, &m)) | |
182 | goto err; /* s = m + xr */ | |
183 | if (BN_cmp(s, dsa->q) > 0) | |
184 | if (!BN_sub(s, s, dsa->q)) | |
185 | goto err; | |
186 | if (!BN_mod_mul(s, s, kinv, dsa->q, ctx)) | |
187 | goto err; | |
188 | ||
189 | ret = DSA_SIG_new(); | |
190 | if (ret == NULL) | |
191 | goto err; | |
192 | ret->r = r; | |
193 | ret->s = s; | |
194 | ||
195 | err: | |
196 | if (!ret) { | |
197 | DSAerr(DSA_F_DSA_DO_SIGN, reason); | |
198 | BN_free(r); | |
199 | BN_free(s); | |
200 | } | |
201 | if (ctx != NULL) | |
202 | BN_CTX_free(ctx); | |
203 | BN_clear_free(&m); | |
204 | BN_clear_free(&xr); | |
205 | if (kinv != NULL) /* dsa->kinv is NULL now if we used it */ | |
206 | BN_clear_free(kinv); | |
207 | return (ret); | |
208 | } | |
209 | ||
210 | static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, | |
211 | BIGNUM **rp) | |
212 | { | |
213 | BN_CTX *ctx; | |
214 | BIGNUM k, kq, *K, *kinv = NULL, *r = NULL; | |
215 | int ret = 0; | |
216 | ||
217 | if (!dsa->p || !dsa->q || !dsa->g) { | |
218 | DSAerr(DSA_F_DSA_SIGN_SETUP, DSA_R_MISSING_PARAMETERS); | |
219 | return 0; | |
220 | } | |
221 | ||
222 | BN_init(&k); | |
223 | BN_init(&kq); | |
224 | ||
225 | if (ctx_in == NULL) { | |
226 | if ((ctx = BN_CTX_new()) == NULL) | |
227 | goto err; | |
228 | } else | |
229 | ctx = ctx_in; | |
230 | ||
231 | if ((r = BN_new()) == NULL) | |
232 | goto err; | |
233 | ||
234 | /* Get random k */ | |
235 | do | |
236 | if (!BN_rand_range(&k, dsa->q)) | |
237 | goto err; | |
238 | while (BN_is_zero(&k)) ; | |
239 | if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) { | |
240 | BN_set_flags(&k, BN_FLG_CONSTTIME); | |
241 | } | |
242 | ||
243 | if (dsa->flags & DSA_FLAG_CACHE_MONT_P) { | |
244 | if (!BN_MONT_CTX_set_locked(&dsa->method_mont_p, | |
245 | CRYPTO_LOCK_DSA, dsa->p, ctx)) | |
246 | goto err; | |
247 | } | |
248 | ||
249 | /* Compute r = (g^k mod p) mod q */ | |
250 | ||
251 | if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) { | |
252 | if (!BN_copy(&kq, &k)) | |
253 | goto err; | |
254 | ||
255 | /* | |
256 | * We do not want timing information to leak the length of k, so we | |
257 | * compute g^k using an equivalent exponent of fixed length. (This | |
258 | * is a kludge that we need because the BN_mod_exp_mont() does not | |
259 | * let us specify the desired timing behaviour.) | |
260 | */ | |
261 | ||
262 | if (!BN_add(&kq, &kq, dsa->q)) | |
263 | goto err; | |
264 | if (BN_num_bits(&kq) <= BN_num_bits(dsa->q)) { | |
265 | if (!BN_add(&kq, &kq, dsa->q)) | |
266 | goto err; | |
267 | } | |
268 | ||
269 | K = &kq; | |
270 | } else { | |
271 | K = &k; | |
272 | } | |
273 | DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, K, dsa->p, ctx, | |
274 | dsa->method_mont_p); | |
275 | if (!BN_mod(r, r, dsa->q, ctx)) | |
276 | goto err; | |
277 | ||
278 | /* Compute part of 's = inv(k) (m + xr) mod q' */ | |
279 | if ((kinv = BN_mod_inverse(NULL, &k, dsa->q, ctx)) == NULL) | |
280 | goto err; | |
281 | ||
282 | if (*kinvp != NULL) | |
283 | BN_clear_free(*kinvp); | |
284 | *kinvp = kinv; | |
285 | kinv = NULL; | |
286 | if (*rp != NULL) | |
287 | BN_clear_free(*rp); | |
288 | *rp = r; | |
289 | ret = 1; | |
290 | err: | |
291 | if (!ret) { | |
292 | DSAerr(DSA_F_DSA_SIGN_SETUP, ERR_R_BN_LIB); | |
293 | if (kinv != NULL) | |
294 | BN_clear_free(kinv); | |
295 | if (r != NULL) | |
296 | BN_clear_free(r); | |
297 | } | |
298 | if (ctx_in == NULL) | |
299 | BN_CTX_free(ctx); | |
300 | if (kinv != NULL) | |
301 | BN_clear_free(kinv); | |
302 | BN_clear_free(&k); | |
303 | BN_clear_free(&kq); | |
304 | return (ret); | |
305 | } | |
306 | ||
307 | static int dsa_do_verify(const unsigned char *dgst, int dgst_len, | |
308 | DSA_SIG *sig, DSA *dsa) | |
309 | { | |
310 | BN_CTX *ctx; | |
311 | BIGNUM u1, u2, t1; | |
312 | BN_MONT_CTX *mont = NULL; | |
313 | int ret = -1; | |
314 | if (!dsa->p || !dsa->q || !dsa->g) { | |
315 | DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_MISSING_PARAMETERS); | |
316 | return -1; | |
317 | } | |
318 | ||
319 | if (BN_num_bits(dsa->q) != 160) { | |
320 | DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_BAD_Q_VALUE); | |
321 | return -1; | |
322 | } | |
323 | ||
324 | if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS) { | |
325 | DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_MODULUS_TOO_LARGE); | |
326 | return -1; | |
327 | } | |
328 | ||
329 | BN_init(&u1); | |
330 | BN_init(&u2); | |
331 | BN_init(&t1); | |
332 | ||
333 | if ((ctx = BN_CTX_new()) == NULL) | |
334 | goto err; | |
335 | ||
336 | if (BN_is_zero(sig->r) || BN_is_negative(sig->r) || | |
337 | BN_ucmp(sig->r, dsa->q) >= 0) { | |
338 | ret = 0; | |
339 | goto err; | |
340 | } | |
341 | if (BN_is_zero(sig->s) || BN_is_negative(sig->s) || | |
342 | BN_ucmp(sig->s, dsa->q) >= 0) { | |
343 | ret = 0; | |
344 | goto err; | |
345 | } | |
346 | ||
347 | /* | |
348 | * Calculate W = inv(S) mod Q save W in u2 | |
349 | */ | |
350 | if ((BN_mod_inverse(&u2, sig->s, dsa->q, ctx)) == NULL) | |
351 | goto err; | |
352 | ||
353 | /* save M in u1 */ | |
354 | if (BN_bin2bn(dgst, dgst_len, &u1) == NULL) | |
355 | goto err; | |
356 | ||
357 | /* u1 = M * w mod q */ | |
358 | if (!BN_mod_mul(&u1, &u1, &u2, dsa->q, ctx)) | |
359 | goto err; | |
360 | ||
361 | /* u2 = r * w mod q */ | |
362 | if (!BN_mod_mul(&u2, sig->r, &u2, dsa->q, ctx)) | |
363 | goto err; | |
364 | ||
365 | if (dsa->flags & DSA_FLAG_CACHE_MONT_P) { | |
366 | mont = BN_MONT_CTX_set_locked(&dsa->method_mont_p, | |
367 | CRYPTO_LOCK_DSA, dsa->p, ctx); | |
368 | if (!mont) | |
369 | goto err; | |
370 | } | |
371 | ||
372 | DSA_MOD_EXP(goto err, dsa, &t1, dsa->g, &u1, dsa->pub_key, &u2, dsa->p, | |
373 | ctx, mont); | |
374 | /* BN_copy(&u1,&t1); */ | |
375 | /* let u1 = u1 mod q */ | |
376 | if (!BN_mod(&u1, &t1, dsa->q, ctx)) | |
377 | goto err; | |
378 | ||
379 | /* | |
380 | * V is now in u1. If the signature is correct, it will be equal to R. | |
381 | */ | |
382 | ret = (BN_ucmp(&u1, sig->r) == 0); | |
383 | ||
384 | err: | |
385 | /* | |
386 | * XXX: surely this is wrong - if ret is 0, it just didn't verify; there | |
387 | * is no error in BN. Test should be ret == -1 (Ben) | |
388 | */ | |
389 | if (ret != 1) | |
390 | DSAerr(DSA_F_DSA_DO_VERIFY, ERR_R_BN_LIB); | |
391 | if (ctx != NULL) | |
392 | BN_CTX_free(ctx); | |
393 | BN_free(&u1); | |
394 | BN_free(&u2); | |
395 | BN_free(&t1); | |
396 | return (ret); | |
397 | } | |
c0711f7f DSH |
398 | |
399 | static int dsa_init(DSA *dsa) | |
400 | { | |
40720ce3 MC |
401 | dsa->flags |= DSA_FLAG_CACHE_MONT_P; |
402 | return (1); | |
c0711f7f DSH |
403 | } |
404 | ||
405 | static int dsa_finish(DSA *dsa) | |
406 | { | |
40720ce3 MC |
407 | if (dsa->method_mont_p) |
408 | BN_MONT_CTX_free(dsa->method_mont_p); | |
409 | return (1); | |
c0711f7f DSH |
410 | } |
411 | ||
e3f2860e | 412 | #endif |