1 /* crypto/dsa/dsa_ossl.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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.
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).
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.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
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)"
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
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.]
59 /* Original version from Steven Schoch <schoch@sheba.arc.nasa.gov> */
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>
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,
73 static int dsa_init(DSA *dsa);
74 static int dsa_finish(DSA *dsa);
76 static DSA_METHOD openssl_dsa_meth = {
81 NULL, /* dsa_mod_exp, */
82 NULL, /* dsa_bn_mod_exp, */
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;
95 * if (!dsa->meth->bn_mod_exp(dsa, r,dsa->g,&k,dsa->p,ctx,
96 * dsa->method_mont_p)) goto err;
100 * DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, &k, dsa->p, ctx,
101 * dsa->method_mont_p);
104 #define DSA_MOD_EXP(err_instr,dsa,rr,a1,p1,a2,p2,m,ctx,in_mont) \
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)); \
111 _tmp_res53 = BN_mod_exp2_mont((rr), (a1), (p1), (a2), (p2), \
112 (m), (ctx), (in_mont)); \
113 if(!_tmp_res53) err_instr; \
115 #define DSA_BN_MOD_EXP(err_instr,dsa,r,a,p,m,ctx,m_ctx) \
118 if((dsa)->meth->bn_mod_exp) \
119 _tmp_res53 = (dsa)->meth->bn_mod_exp((dsa), (r), (a), (p), \
120 (m), (ctx), (m_ctx)); \
122 _tmp_res53 = BN_mod_exp_mont((r), (a), (p), (m), (ctx), (m_ctx)); \
123 if(!_tmp_res53) err_instr; \
126 const DSA_METHOD *DSA_OpenSSL(void)
128 return &openssl_dsa_meth;
131 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
133 BIGNUM *kinv=NULL,*r=NULL,*s=NULL;
137 int reason=ERR_R_BN_LIB;
144 if (!dsa->p || !dsa->q || !dsa->g)
146 reason=DSA_R_MISSING_PARAMETERS;
151 if (s == NULL) goto err;
153 /* reject a excessive digest length (currently at most
154 * dsa-with-SHA256 is supported) */
155 if (dlen > SHA256_DIGEST_LENGTH)
157 reason=DSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE;
162 if (ctx == NULL) goto err;
164 if ((dsa->kinv == NULL) || (dsa->r == NULL))
166 if (!DSA_sign_setup(dsa,ctx,&kinv,&r)) goto err;
178 if (dlen > BN_num_bytes(dsa->q))
179 /* if the digest length is greater than the size of q use the
180 * BN_num_bits(dsa->q) leftmost bits of the digest, see
182 dlen = BN_num_bytes(dsa->q);
183 if (BN_bin2bn(dgst,dlen,&m) == NULL)
186 /* Compute s = inv(k) (m + xr) mod q */
187 if (!BN_mod_mul(&xr,dsa->priv_key,r,dsa->q,ctx)) goto err;/* s = xr */
188 if (!BN_add(s, &xr, &m)) goto err; /* s = m + xr */
189 if (BN_cmp(s,dsa->q) > 0)
190 if (!BN_sub(s,s,dsa->q)) goto err;
191 if (!BN_mod_mul(s,s,kinv,dsa->q,ctx)) goto err;
194 if (ret == NULL) goto err;
195 /* Redo if r or s is zero as required by FIPS 186-3: this is
198 if (BN_is_zero(r) || BN_is_zero(s))
202 reason = DSA_R_NEED_NEW_SETUP_VALUES;
213 DSAerr(DSA_F_DSA_DO_SIGN,reason);
217 if (ctx != NULL) BN_CTX_free(ctx);
220 if (kinv != NULL) /* dsa->kinv is NULL now if we used it */
225 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
228 BIGNUM k,kq,*K,*kinv=NULL,*r=NULL;
231 if (!dsa->p || !dsa->q || !dsa->g)
233 DSAerr(DSA_F_DSA_SIGN_SETUP,DSA_R_MISSING_PARAMETERS);
242 if ((ctx=BN_CTX_new()) == NULL) goto err;
247 if ((r=BN_new()) == NULL) goto err;
251 if (!BN_rand_range(&k, dsa->q)) goto err;
252 while (BN_is_zero(&k));
253 if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)
255 BN_set_flags(&k, BN_FLG_CONSTTIME);
258 if (dsa->flags & DSA_FLAG_CACHE_MONT_P)
260 if (!BN_MONT_CTX_set_locked(&dsa->method_mont_p,
266 /* Compute r = (g^k mod p) mod q */
268 if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)
270 if (!BN_copy(&kq, &k)) goto err;
272 /* We do not want timing information to leak the length of k,
273 * so we compute g^k using an equivalent exponent of fixed length.
275 * (This is a kludge that we need because the BN_mod_exp_mont()
276 * does not let us specify the desired timing behaviour.) */
278 if (!BN_add(&kq, &kq, dsa->q)) goto err;
279 if (BN_num_bits(&kq) <= BN_num_bits(dsa->q))
281 if (!BN_add(&kq, &kq, dsa->q)) goto err;
290 DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, K, dsa->p, ctx,
292 if (!BN_mod(r,r,dsa->q,ctx)) goto err;
294 /* Compute part of 's = inv(k) (m + xr) mod q' */
295 if ((kinv=BN_mod_inverse(NULL,&k,dsa->q,ctx)) == NULL) goto err;
297 if (*kinvp != NULL) BN_clear_free(*kinvp);
300 if (*rp != NULL) BN_clear_free(*rp);
306 DSAerr(DSA_F_DSA_SIGN_SETUP,ERR_R_BN_LIB);
310 if (ctx_in == NULL) BN_CTX_free(ctx);
316 static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
321 BN_MONT_CTX *mont=NULL;
323 if (!dsa->p || !dsa->q || !dsa->g)
325 DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MISSING_PARAMETERS);
329 i = BN_num_bits(dsa->q);
330 /* fips 186-3 allows only different sizes for q */
331 if (i != 160 && i != 224 && i != 256)
333 DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_BAD_Q_VALUE);
337 if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS)
339 DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MODULUS_TOO_LARGE);
343 /* reject a excessive digest length (currently at most
344 * dsa-with-SHA256 is supported) */
345 if (dgst_len > SHA256_DIGEST_LENGTH)
347 DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
355 if ((ctx=BN_CTX_new()) == NULL) goto err;
357 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
358 BN_ucmp(sig->r, dsa->q) >= 0)
363 if (BN_is_zero(sig->s) || BN_is_negative(sig->s) ||
364 BN_ucmp(sig->s, dsa->q) >= 0)
370 /* Calculate W = inv(S) mod Q
372 if ((BN_mod_inverse(&u2,sig->s,dsa->q,ctx)) == NULL) goto err;
375 if (dgst_len > (i >> 3))
376 /* if the digest length is greater than the size of q use the
377 * BN_num_bits(dsa->q) leftmost bits of the digest, see
380 if (BN_bin2bn(dgst,dgst_len,&u1) == NULL) goto err;
382 /* u1 = M * w mod q */
383 if (!BN_mod_mul(&u1,&u1,&u2,dsa->q,ctx)) goto err;
385 /* u2 = r * w mod q */
386 if (!BN_mod_mul(&u2,sig->r,&u2,dsa->q,ctx)) goto err;
389 if (dsa->flags & DSA_FLAG_CACHE_MONT_P)
391 mont = BN_MONT_CTX_set_locked(&dsa->method_mont_p,
392 CRYPTO_LOCK_DSA, dsa->p, ctx);
398 DSA_MOD_EXP(goto err, dsa, &t1, dsa->g, &u1, dsa->pub_key, &u2, dsa->p, ctx, mont);
399 /* BN_copy(&u1,&t1); */
400 /* let u1 = u1 mod q */
401 if (!BN_mod(&u1,&t1,dsa->q,ctx)) goto err;
403 /* V is now in u1. If the signature is correct, it will be
405 ret=(BN_ucmp(&u1, sig->r) == 0);
408 /* XXX: surely this is wrong - if ret is 0, it just didn't verify;
409 there is no error in BN. Test should be ret == -1 (Ben) */
410 if (ret != 1) DSAerr(DSA_F_DSA_DO_VERIFY,ERR_R_BN_LIB);
411 if (ctx != NULL) BN_CTX_free(ctx);
418 static int dsa_init(DSA *dsa)
420 dsa->flags|=DSA_FLAG_CACHE_MONT_P;
424 static int dsa_finish(DSA *dsa)
426 if(dsa->method_mont_p)
427 BN_MONT_CTX_free(dsa->method_mont_p);