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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. | |
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/dsa.h> | |
65 | #include <openssl/rand.h> | |
66 | #include <openssl/asn1.h> | |
67 | ||
68 | static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa); | |
ce1b4fe1 | 69 | static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp); |
c0711f7f DSH |
70 | static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig, |
71 | DSA *dsa); | |
72 | static int dsa_init(DSA *dsa); | |
73 | static int dsa_finish(DSA *dsa); | |
c0711f7f DSH |
74 | |
75 | static DSA_METHOD openssl_dsa_meth = { | |
76 | "OpenSSL DSA method", | |
77 | dsa_do_sign, | |
78 | dsa_sign_setup, | |
79 | dsa_do_verify, | |
879650b8 GT |
80 | NULL, /* dsa_mod_exp, */ |
81 | NULL, /* dsa_bn_mod_exp, */ | |
c0711f7f DSH |
82 | dsa_init, |
83 | dsa_finish, | |
84 | 0, | |
0e4aa0d2 GT |
85 | NULL, |
86 | NULL, | |
c0711f7f DSH |
87 | NULL |
88 | }; | |
89 | ||
879650b8 GT |
90 | /* These macro wrappers replace attempts to use the dsa_mod_exp() and |
91 | * bn_mod_exp() handlers in the DSA_METHOD structure. We avoid the problem of | |
92 | * having a the macro work as an expression by bundling an "err_instr". So; | |
93 | * | |
94 | * if (!dsa->meth->bn_mod_exp(dsa, r,dsa->g,&k,dsa->p,ctx, | |
95 | * dsa->method_mont_p)) goto err; | |
96 | * | |
97 | * can be replaced by; | |
98 | * | |
99 | * DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, &k, dsa->p, ctx, | |
100 | * dsa->method_mont_p); | |
101 | */ | |
102 | ||
103 | #define DSA_MOD_EXP(err_instr,dsa,rr,a1,p1,a2,p2,m,ctx,in_mont) \ | |
104 | do { \ | |
105 | int _tmp_res53; \ | |
106 | if((dsa)->meth->dsa_mod_exp) \ | |
107 | _tmp_res53 = (dsa)->meth->dsa_mod_exp((dsa), (rr), (a1), (p1), \ | |
108 | (a2), (p2), (m), (ctx), (in_mont)); \ | |
109 | else \ | |
110 | _tmp_res53 = BN_mod_exp2_mont((rr), (a1), (p1), (a2), (p2), \ | |
111 | (m), (ctx), (in_mont)); \ | |
112 | if(!_tmp_res53) err_instr; \ | |
113 | } while(0) | |
114 | #define DSA_BN_MOD_EXP(err_instr,dsa,r,a,p,m,ctx,m_ctx) \ | |
115 | do { \ | |
116 | int _tmp_res53; \ | |
117 | if((dsa)->meth->bn_mod_exp) \ | |
118 | _tmp_res53 = (dsa)->meth->bn_mod_exp((dsa), (r), (a), (p), \ | |
119 | (m), (ctx), (m_ctx)); \ | |
120 | else \ | |
121 | _tmp_res53 = BN_mod_exp_mont((r), (a), (p), (m), (ctx), (m_ctx)); \ | |
122 | if(!_tmp_res53) err_instr; \ | |
123 | } while(0) | |
124 | ||
a4aba800 | 125 | const DSA_METHOD *DSA_OpenSSL(void) |
c0711f7f DSH |
126 | { |
127 | return &openssl_dsa_meth; | |
128 | } | |
129 | ||
130 | static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa) | |
131 | { | |
132 | BIGNUM *kinv=NULL,*r=NULL,*s=NULL; | |
133 | BIGNUM m; | |
134 | BIGNUM xr; | |
135 | BN_CTX *ctx=NULL; | |
136 | int i,reason=ERR_R_BN_LIB; | |
137 | DSA_SIG *ret=NULL; | |
138 | ||
a74333f9 LJ |
139 | BN_init(&m); |
140 | BN_init(&xr); | |
141 | ||
c962479b DSH |
142 | if (!dsa->p || !dsa->q || !dsa->g) |
143 | { | |
144 | reason=DSA_R_MISSING_PARAMETERS; | |
145 | goto err; | |
146 | } | |
a74333f9 | 147 | |
c0711f7f DSH |
148 | s=BN_new(); |
149 | if (s == NULL) goto err; | |
150 | ||
151 | i=BN_num_bytes(dsa->q); /* should be 20 */ | |
152 | if ((dlen > i) || (dlen > 50)) | |
153 | { | |
154 | reason=DSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE; | |
155 | goto err; | |
156 | } | |
157 | ||
158 | ctx=BN_CTX_new(); | |
159 | if (ctx == NULL) goto err; | |
160 | ||
161 | if ((dsa->kinv == NULL) || (dsa->r == NULL)) | |
162 | { | |
163 | if (!DSA_sign_setup(dsa,ctx,&kinv,&r)) goto err; | |
164 | } | |
165 | else | |
166 | { | |
167 | kinv=dsa->kinv; | |
168 | dsa->kinv=NULL; | |
169 | r=dsa->r; | |
170 | dsa->r=NULL; | |
171 | } | |
172 | ||
173 | if (BN_bin2bn(dgst,dlen,&m) == NULL) goto err; | |
174 | ||
175 | /* Compute s = inv(k) (m + xr) mod q */ | |
176 | if (!BN_mod_mul(&xr,dsa->priv_key,r,dsa->q,ctx)) goto err;/* s = xr */ | |
177 | if (!BN_add(s, &xr, &m)) goto err; /* s = m + xr */ | |
178 | if (BN_cmp(s,dsa->q) > 0) | |
179 | BN_sub(s,s,dsa->q); | |
180 | if (!BN_mod_mul(s,s,kinv,dsa->q,ctx)) goto err; | |
181 | ||
182 | ret=DSA_SIG_new(); | |
183 | if (ret == NULL) goto err; | |
184 | ret->r = r; | |
185 | ret->s = s; | |
186 | ||
187 | err: | |
188 | if (!ret) | |
189 | { | |
190 | DSAerr(DSA_F_DSA_DO_SIGN,reason); | |
191 | BN_free(r); | |
192 | BN_free(s); | |
193 | } | |
194 | if (ctx != NULL) 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 | ||
ce1b4fe1 | 202 | static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp) |
c0711f7f DSH |
203 | { |
204 | BN_CTX *ctx; | |
0ebfcc8f | 205 | BIGNUM k,kq,*K,*kinv=NULL,*r=NULL; |
c0711f7f DSH |
206 | int ret=0; |
207 | ||
c962479b DSH |
208 | if (!dsa->p || !dsa->q || !dsa->g) |
209 | { | |
210 | DSAerr(DSA_F_DSA_SIGN_SETUP,DSA_R_MISSING_PARAMETERS); | |
211 | return 0; | |
212 | } | |
a74333f9 LJ |
213 | |
214 | BN_init(&k); | |
0ebfcc8f | 215 | BN_init(&kq); |
a74333f9 | 216 | |
c0711f7f DSH |
217 | if (ctx_in == NULL) |
218 | { | |
219 | if ((ctx=BN_CTX_new()) == NULL) goto err; | |
220 | } | |
221 | else | |
222 | ctx=ctx_in; | |
223 | ||
c0711f7f | 224 | if ((r=BN_new()) == NULL) goto err; |
c0711f7f DSH |
225 | |
226 | /* Get random k */ | |
35ed8cb8 | 227 | do |
e3068929 | 228 | if (!BN_rand_range(&k, dsa->q)) goto err; |
35ed8cb8 | 229 | while (BN_is_zero(&k)); |
46a64376 BM |
230 | if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) |
231 | { | |
232 | BN_set_flags(&k, BN_FLG_EXP_CONSTTIME); | |
233 | } | |
c0711f7f | 234 | |
6ec8e63a | 235 | if (dsa->flags & DSA_FLAG_CACHE_MONT_P) |
c0711f7f | 236 | { |
879b1980 | 237 | if (!BN_MONT_CTX_set_locked(&dsa->method_mont_p, |
6ec8e63a DSH |
238 | CRYPTO_LOCK_DSA, |
239 | dsa->p, ctx)) | |
240 | goto err; | |
c0711f7f DSH |
241 | } |
242 | ||
243 | /* Compute r = (g^k mod p) mod q */ | |
0ebfcc8f BM |
244 | |
245 | if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) | |
246 | { | |
247 | if (!BN_copy(&kq, &k)) goto err; | |
248 | ||
249 | /* We do not want timing information to leak the length of k, | |
250 | * so we compute g^k using an equivalent exponent of fixed length. | |
251 | * | |
252 | * (This is a kludge that we need because the BN_mod_exp_mont() | |
253 | * does not let us specify the desired timing behaviour.) */ | |
254 | ||
255 | if (!BN_add(&kq, &kq, dsa->q)) goto err; | |
256 | if (BN_num_bits(&kq) <= BN_num_bits(dsa->q)) | |
257 | { | |
258 | if (!BN_add(&kq, &kq, dsa->q)) goto err; | |
259 | } | |
260 | ||
261 | K = &kq; | |
262 | } | |
263 | else | |
264 | { | |
265 | K = &k; | |
266 | } | |
267 | DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, K, dsa->p, ctx, | |
879b1980 | 268 | dsa->method_mont_p); |
c0711f7f DSH |
269 | if (!BN_mod(r,r,dsa->q,ctx)) 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) goto err; | |
273 | ||
274 | if (*kinvp != NULL) BN_clear_free(*kinvp); | |
275 | *kinvp=kinv; | |
276 | kinv=NULL; | |
277 | if (*rp != NULL) BN_clear_free(*rp); | |
278 | *rp=r; | |
279 | ret=1; | |
280 | err: | |
281 | if (!ret) | |
282 | { | |
283 | DSAerr(DSA_F_DSA_SIGN_SETUP,ERR_R_BN_LIB); | |
67b6f1ca NL |
284 | if (r != NULL) |
285 | BN_clear_free(r); | |
c0711f7f DSH |
286 | } |
287 | if (ctx_in == NULL) BN_CTX_free(ctx); | |
c0711f7f | 288 | BN_clear_free(&k); |
0ebfcc8f | 289 | BN_clear_free(&kq); |
c0711f7f DSH |
290 | return(ret); |
291 | } | |
292 | ||
293 | static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig, | |
294 | DSA *dsa) | |
295 | { | |
296 | BN_CTX *ctx; | |
297 | BIGNUM u1,u2,t1; | |
298 | BN_MONT_CTX *mont=NULL; | |
299 | int ret = -1; | |
c962479b DSH |
300 | if (!dsa->p || !dsa->q || !dsa->g) |
301 | { | |
302 | DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MISSING_PARAMETERS); | |
303 | return -1; | |
304 | } | |
c0711f7f | 305 | |
5e3225cc BM |
306 | if (BN_num_bits(dsa->q) != 160) |
307 | { | |
308 | DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_BAD_Q_VALUE); | |
309 | return -1; | |
310 | } | |
311 | ||
312 | if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS) | |
313 | { | |
314 | DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MODULUS_TOO_LARGE); | |
315 | return -1; | |
316 | } | |
317 | ||
c0711f7f DSH |
318 | BN_init(&u1); |
319 | BN_init(&u2); | |
320 | BN_init(&t1); | |
321 | ||
a74333f9 LJ |
322 | if ((ctx=BN_CTX_new()) == NULL) goto err; |
323 | ||
ff22e913 | 324 | if (BN_is_zero(sig->r) || BN_is_negative(sig->r) || |
b53e44e5 | 325 | BN_ucmp(sig->r, dsa->q) >= 0) |
c458a331 BM |
326 | { |
327 | ret = 0; | |
328 | goto err; | |
329 | } | |
ff22e913 | 330 | if (BN_is_zero(sig->s) || BN_is_negative(sig->s) || |
b53e44e5 | 331 | BN_ucmp(sig->s, dsa->q) >= 0) |
c458a331 BM |
332 | { |
333 | ret = 0; | |
334 | goto err; | |
335 | } | |
336 | ||
c0711f7f DSH |
337 | /* Calculate W = inv(S) mod Q |
338 | * save W in u2 */ | |
339 | if ((BN_mod_inverse(&u2,sig->s,dsa->q,ctx)) == NULL) goto err; | |
340 | ||
341 | /* save M in u1 */ | |
342 | if (BN_bin2bn(dgst,dgst_len,&u1) == NULL) goto err; | |
343 | ||
344 | /* u1 = M * w mod q */ | |
345 | if (!BN_mod_mul(&u1,&u1,&u2,dsa->q,ctx)) goto err; | |
346 | ||
347 | /* u2 = r * w mod q */ | |
348 | if (!BN_mod_mul(&u2,sig->r,&u2,dsa->q,ctx)) goto err; | |
349 | ||
6ec8e63a DSH |
350 | |
351 | if (dsa->flags & DSA_FLAG_CACHE_MONT_P) | |
c0711f7f | 352 | { |
879b1980 | 353 | mont = BN_MONT_CTX_set_locked(&dsa->method_mont_p, |
6ec8e63a DSH |
354 | CRYPTO_LOCK_DSA, dsa->p, ctx); |
355 | if (!mont) | |
356 | goto err; | |
c0711f7f | 357 | } |
c0711f7f | 358 | |
879650b8 GT |
359 | |
360 | DSA_MOD_EXP(goto err, dsa, &t1, dsa->g, &u1, dsa->pub_key, &u2, dsa->p, ctx, mont); | |
c0711f7f DSH |
361 | /* BN_copy(&u1,&t1); */ |
362 | /* let u1 = u1 mod q */ | |
363 | if (!BN_mod(&u1,&t1,dsa->q,ctx)) goto err; | |
879650b8 | 364 | |
c0711f7f DSH |
365 | /* V is now in u1. If the signature is correct, it will be |
366 | * equal to R. */ | |
367 | ret=(BN_ucmp(&u1, sig->r) == 0); | |
368 | ||
369 | err: | |
b0ac0a8e | 370 | /* XXX: surely this is wrong - if ret is 0, it just didn't verify; |
e9ad6665 | 371 | there is no error in BN. Test should be ret == -1 (Ben) */ |
c0711f7f DSH |
372 | if (ret != 1) DSAerr(DSA_F_DSA_DO_VERIFY,ERR_R_BN_LIB); |
373 | if (ctx != NULL) BN_CTX_free(ctx); | |
374 | BN_free(&u1); | |
375 | BN_free(&u2); | |
376 | BN_free(&t1); | |
377 | return(ret); | |
378 | } | |
379 | ||
380 | static int dsa_init(DSA *dsa) | |
381 | { | |
13066cee | 382 | dsa->flags|=DSA_FLAG_CACHE_MONT_P; |
c0711f7f DSH |
383 | return(1); |
384 | } | |
385 | ||
386 | static int dsa_finish(DSA *dsa) | |
387 | { | |
13066cee | 388 | if(dsa->method_mont_p) |
879b1980 | 389 | BN_MONT_CTX_free(dsa->method_mont_p); |
c0711f7f DSH |
390 | return(1); |
391 | } | |
392 |