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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. | |
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 #include "cryptlib.h" | |
63 #include <openssl/bn.h> | |
64 #include <openssl/sha.h> | |
65 #include <openssl/dsa.h> | |
66 #include <openssl/rand.h> | |
67 #include <openssl/asn1.h> | |
68 | |
69 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa); | |
70 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
; | |
71 static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig, | |
72 DSA *dsa); | |
73 static int dsa_init(DSA *dsa); | |
74 static int dsa_finish(DSA *dsa); | |
75 | |
76 static DSA_METHOD openssl_dsa_meth = { | |
77 "OpenSSL DSA method", | |
78 dsa_do_sign, | |
79 dsa_sign_setup, | |
80 dsa_do_verify, | |
81 NULL, /* dsa_mod_exp, */ | |
82 NULL, /* dsa_bn_mod_exp, */ | |
83 dsa_init, | |
84 dsa_finish, | |
85 0, | |
86 NULL, | |
87 NULL, | |
88 NULL | |
89 }; | |
90 | |
91 /* These macro wrappers replace attempts to use the dsa_mod_exp() and | |
92 * bn_mod_exp() handlers in the DSA_METHOD structure. We avoid the problem of | |
93 * having a the macro work as an expression by bundling an "err_instr". So; | |
94 * | |
95 * if (!dsa->meth->bn_mod_exp(dsa, r,dsa->g,&k,dsa->p,ctx, | |
96 * dsa->method_mont_p)) goto err; | |
97 * | |
98 * can be replaced by; | |
99 * | |
100 * DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, &k, dsa->p, ctx, | |
101 * dsa->method_mont_p); | |
102 */ | |
103 | |
104 #define DSA_MOD_EXP(err_instr,dsa,rr,a1,p1,a2,p2,m,ctx,in_mont) \ | |
105 do { \ | |
106 int _tmp_res53; \ | |
107 if((dsa)->meth->dsa_mod_exp) \ | |
108 _tmp_res53 = (dsa)->meth->dsa_mod_exp((dsa), (rr), (a1), (p1), \ | |
109 (a2), (p2), (m), (ctx), (in_mont)); \ | |
110 else \ | |
111 _tmp_res53 = BN_mod_exp2_mont((rr), (a1), (p1), (a2), (p2), \ | |
112 (m), (ctx), (in_mont)); \ | |
113 if(!_tmp_res53) err_instr; \ | |
114 } while(0) | |
115 #define DSA_BN_MOD_EXP(err_instr,dsa,r,a,p,m,ctx,m_ctx) \ | |
116 do { \ | |
117 int _tmp_res53; \ | |
118 if((dsa)->meth->bn_mod_exp) \ | |
119 _tmp_res53 = (dsa)->meth->bn_mod_exp((dsa), (r), (a), (p), \ | |
120 (m), (ctx), (m_ctx)); \ | |
121 else \ | |
122 _tmp_res53 = BN_mod_exp_mont((r), (a), (p), (m), (ctx), (m_ctx))
; \ | |
123 if(!_tmp_res53) err_instr; \ | |
124 } while(0) | |
125 | |
126 const DSA_METHOD *DSA_OpenSSL(void) | |
127 { | |
128 return &openssl_dsa_meth; | |
129 } | |
130 | |
131 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa) | |
132 { | |
133 BIGNUM *kinv=NULL,*r=NULL,*s=NULL; | |
134 BIGNUM m; | |
135 BIGNUM xr; | |
136 BN_CTX *ctx=NULL; | |
137 int reason=ERR_R_BN_LIB; | |
138 DSA_SIG *ret=NULL; | |
139 int noredo = 0; | |
140 | |
141 BN_init(&m); | |
142 BN_init(&xr); | |
143 | |
144 if (!dsa->p || !dsa->q || !dsa->g) | |
145 { | |
146 reason=DSA_R_MISSING_PARAMETERS; | |
147 goto err; | |
148 } | |
149 | |
150 s=BN_new(); | |
151 if (s == NULL) goto err; | |
152 ctx=BN_CTX_new(); | |
153 if (ctx == NULL) goto err; | |
154 redo: | |
155 if ((dsa->kinv == NULL) || (dsa->r == NULL)) | |
156 { | |
157 if (!DSA_sign_setup(dsa,ctx,&kinv,&r)) goto err; | |
158 } | |
159 else | |
160 { | |
161 kinv=dsa->kinv; | |
162 dsa->kinv=NULL; | |
163 r=dsa->r; | |
164 dsa->r=NULL; | |
165 noredo = 1; | |
166 } | |
167 | |
168 | |
169 if (dlen > BN_num_bytes(dsa->q)) | |
170 /* if the digest length is greater than the size of q use the | |
171 * BN_num_bits(dsa->q) leftmost bits of the digest, see | |
172 * fips 186-3, 4.2 */ | |
173 dlen = BN_num_bytes(dsa->q); | |
174 if (BN_bin2bn(dgst,dlen,&m) == NULL) | |
175 goto err; | |
176 | |
177 /* Compute s = inv(k) (m + xr) mod q */ | |
178 if (!BN_mod_mul(&xr,dsa->priv_key,r,dsa->q,ctx)) goto err;/* s = xr */ | |
179 if (!BN_add(s, &xr, &m)) goto err; /* s = m + xr */ | |
180 if (BN_cmp(s,dsa->q) > 0) | |
181 if (!BN_sub(s,s,dsa->q)) goto err; | |
182 if (!BN_mod_mul(s,s,kinv,dsa->q,ctx)) goto err; | |
183 | |
184 ret=DSA_SIG_new(); | |
185 if (ret == NULL) goto err; | |
186 /* Redo if r or s is zero as required by FIPS 186-3: this is | |
187 * very unlikely. | |
188 */ | |
189 if (BN_is_zero(r) || BN_is_zero(s)) | |
190 { | |
191 if (noredo) | |
192 { | |
193 reason = DSA_R_NEED_NEW_SETUP_VALUES; | |
194 goto err; | |
195 } | |
196 goto redo; | |
197 } | |
198 ret->r = r; | |
199 ret->s = s; | |
200 | |
201 err: | |
202 if (!ret) | |
203 { | |
204 DSAerr(DSA_F_DSA_DO_SIGN,reason); | |
205 BN_free(r); | |
206 BN_free(s); | |
207 } | |
208 if (ctx != NULL) BN_CTX_free(ctx); | |
209 BN_clear_free(&m); | |
210 BN_clear_free(&xr); | |
211 if (kinv != NULL) /* dsa->kinv is NULL now if we used it */ | |
212 BN_clear_free(kinv); | |
213 return(ret); | |
214 } | |
215 | |
216 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp) | |
217 { | |
218 BN_CTX *ctx; | |
219 BIGNUM k,kq,*K,*kinv=NULL,*r=NULL; | |
220 int ret=0; | |
221 | |
222 if (!dsa->p || !dsa->q || !dsa->g) | |
223 { | |
224 DSAerr(DSA_F_DSA_SIGN_SETUP,DSA_R_MISSING_PARAMETERS); | |
225 return 0; | |
226 } | |
227 | |
228 BN_init(&k); | |
229 BN_init(&kq); | |
230 | |
231 if (ctx_in == NULL) | |
232 { | |
233 if ((ctx=BN_CTX_new()) == NULL) goto err; | |
234 } | |
235 else | |
236 ctx=ctx_in; | |
237 | |
238 if ((r=BN_new()) == NULL) goto err; | |
239 | |
240 /* Get random k */ | |
241 do | |
242 if (!BN_rand_range(&k, dsa->q)) goto err; | |
243 while (BN_is_zero(&k)); | |
244 if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) | |
245 { | |
246 BN_set_flags(&k, BN_FLG_CONSTTIME); | |
247 } | |
248 | |
249 if (dsa->flags & DSA_FLAG_CACHE_MONT_P) | |
250 { | |
251 if (!BN_MONT_CTX_set_locked(&dsa->method_mont_p, | |
252 CRYPTO_LOCK_DSA, | |
253 dsa->p, ctx)) | |
254 goto err; | |
255 } | |
256 | |
257 /* Compute r = (g^k mod p) mod q */ | |
258 | |
259 if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) | |
260 { | |
261 if (!BN_copy(&kq, &k)) goto err; | |
262 | |
263 /* We do not want timing information to leak the length of k, | |
264 * so we compute g^k using an equivalent exponent of fixed lengt
h. | |
265 * | |
266 * (This is a kludge that we need because the BN_mod_exp_mont() | |
267 * does not let us specify the desired timing behaviour.) */ | |
268 | |
269 if (!BN_add(&kq, &kq, dsa->q)) goto err; | |
270 if (BN_num_bits(&kq) <= BN_num_bits(dsa->q)) | |
271 { | |
272 if (!BN_add(&kq, &kq, dsa->q)) goto err; | |
273 } | |
274 | |
275 K = &kq; | |
276 } | |
277 else | |
278 { | |
279 K = &k; | |
280 } | |
281 DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, K, dsa->p, ctx, | |
282 dsa->method_mont_p); | |
283 if (!BN_mod(r,r,dsa->q,ctx)) goto err; | |
284 | |
285 /* Compute part of 's = inv(k) (m + xr) mod q' */ | |
286 if ((kinv=BN_mod_inverse(NULL,&k,dsa->q,ctx)) == NULL) goto err; | |
287 | |
288 if (*kinvp != NULL) BN_clear_free(*kinvp); | |
289 *kinvp=kinv; | |
290 kinv=NULL; | |
291 if (*rp != NULL) BN_clear_free(*rp); | |
292 *rp=r; | |
293 ret=1; | |
294 err: | |
295 if (!ret) | |
296 { | |
297 DSAerr(DSA_F_DSA_SIGN_SETUP,ERR_R_BN_LIB); | |
298 if (r != NULL) | |
299 BN_clear_free(r); | |
300 } | |
301 if (ctx_in == NULL) BN_CTX_free(ctx); | |
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, DSA_SIG *sig, | |
308 DSA *dsa) | |
309 { | |
310 BN_CTX *ctx; | |
311 BIGNUM u1,u2,t1; | |
312 BN_MONT_CTX *mont=NULL; | |
313 int ret = -1, i; | |
314 if (!dsa->p || !dsa->q || !dsa->g) | |
315 { | |
316 DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MISSING_PARAMETERS); | |
317 return -1; | |
318 } | |
319 | |
320 i = BN_num_bits(dsa->q); | |
321 /* fips 186-3 allows only different sizes for q */ | |
322 if (i != 160 && i != 224 && i != 256) | |
323 { | |
324 DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_BAD_Q_VALUE); | |
325 return -1; | |
326 } | |
327 | |
328 if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS) | |
329 { | |
330 DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MODULUS_TOO_LARGE); | |
331 return -1; | |
332 } | |
333 BN_init(&u1); | |
334 BN_init(&u2); | |
335 BN_init(&t1); | |
336 | |
337 if ((ctx=BN_CTX_new()) == NULL) goto err; | |
338 | |
339 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) || | |
340 BN_ucmp(sig->r, dsa->q) >= 0) | |
341 { | |
342 ret = 0; | |
343 goto err; | |
344 } | |
345 if (BN_is_zero(sig->s) || BN_is_negative(sig->s) || | |
346 BN_ucmp(sig->s, dsa->q) >= 0) | |
347 { | |
348 ret = 0; | |
349 goto err; | |
350 } | |
351 | |
352 /* Calculate W = inv(S) mod Q | |
353 * save W in u2 */ | |
354 if ((BN_mod_inverse(&u2,sig->s,dsa->q,ctx)) == NULL) goto err; | |
355 | |
356 /* save M in u1 */ | |
357 if (dgst_len > (i >> 3)) | |
358 /* if the digest length is greater than the size of q use the | |
359 * BN_num_bits(dsa->q) leftmost bits of the digest, see | |
360 * fips 186-3, 4.2 */ | |
361 dgst_len = (i >> 3); | |
362 if (BN_bin2bn(dgst,dgst_len,&u1) == NULL) goto err; | |
363 | |
364 /* u1 = M * w mod q */ | |
365 if (!BN_mod_mul(&u1,&u1,&u2,dsa->q,ctx)) goto err; | |
366 | |
367 /* u2 = r * w mod q */ | |
368 if (!BN_mod_mul(&u2,sig->r,&u2,dsa->q,ctx)) goto err; | |
369 | |
370 | |
371 if (dsa->flags & DSA_FLAG_CACHE_MONT_P) | |
372 { | |
373 mont = BN_MONT_CTX_set_locked(&dsa->method_mont_p, | |
374 CRYPTO_LOCK_DSA, dsa->p, ctx); | |
375 if (!mont) | |
376 goto err; | |
377 } | |
378 | |
379 | |
380 DSA_MOD_EXP(goto err, dsa, &t1, dsa->g, &u1, dsa->pub_key, &u2, dsa->p,
ctx, mont); | |
381 /* BN_copy(&u1,&t1); */ | |
382 /* let u1 = u1 mod q */ | |
383 if (!BN_mod(&u1,&t1,dsa->q,ctx)) goto err; | |
384 | |
385 /* V is now in u1. If the signature is correct, it will be | |
386 * equal to R. */ | |
387 ret=(BN_ucmp(&u1, sig->r) == 0); | |
388 | |
389 err: | |
390 /* XXX: surely this is wrong - if ret is 0, it just didn't verify; | |
391 there is no error in BN. Test should be ret == -1 (Ben) */ | |
392 if (ret != 1) DSAerr(DSA_F_DSA_DO_VERIFY,ERR_R_BN_LIB); | |
393 if (ctx != NULL) BN_CTX_free(ctx); | |
394 BN_free(&u1); | |
395 BN_free(&u2); | |
396 BN_free(&t1); | |
397 return(ret); | |
398 } | |
399 | |
400 static int dsa_init(DSA *dsa) | |
401 { | |
402 dsa->flags|=DSA_FLAG_CACHE_MONT_P; | |
403 return(1); | |
404 } | |
405 | |
406 static int dsa_finish(DSA *dsa) | |
407 { | |
408 if(dsa->method_mont_p) | |
409 BN_MONT_CTX_free(dsa->method_mont_p); | |
410 return(1); | |
411 } | |
412 | |
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