/* crypto/dsa/dsa_ossl.c */ /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) * All rights reserved. * * This package is an SSL implementation written * by Eric Young (eay@cryptsoft.com). * The implementation was written so as to conform with Netscapes SSL. * * This library is free for commercial and non-commercial use as long as * the following conditions are aheared to. The following conditions * apply to all code found in this distribution, be it the RC4, RSA, * lhash, DES, etc., code; not just the SSL code. The SSL documentation * included with this distribution is covered by the same copyright terms * except that the holder is Tim Hudson (tjh@cryptsoft.com). * * Copyright remains Eric Young's, and as such any Copyright notices in * the code are not to be removed. * If this package is used in a product, Eric Young should be given attribution * as the author of the parts of the library used. * This can be in the form of a textual message at program startup or * in documentation (online or textual) provided with the package. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * "This product includes cryptographic software written by * Eric Young (eay@cryptsoft.com)" * The word 'cryptographic' can be left out if the rouines from the library * being used are not cryptographic related :-). * 4. If you include any Windows specific code (or a derivative thereof) from * the apps directory (application code) you must include an acknowledgement: * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" * * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * The licence and distribution terms for any publically available version or * derivative of this code cannot be changed. i.e. this code cannot simply be * copied and put under another distribution licence * [including the GNU Public Licence.] */ /* Original version from Steven Schoch */ #include #include "cryptlib.h" #include #include #include #include static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa); static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp); static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig, DSA *dsa); static int dsa_init(DSA *dsa); static int dsa_finish(DSA *dsa); static DSA_METHOD openssl_dsa_meth = { "OpenSSL DSA method", dsa_do_sign, dsa_sign_setup, dsa_do_verify, NULL, /* dsa_mod_exp, */ NULL, /* dsa_bn_mod_exp, */ dsa_init, dsa_finish, 0, NULL, NULL, NULL }; /* These macro wrappers replace attempts to use the dsa_mod_exp() and * bn_mod_exp() handlers in the DSA_METHOD structure. We avoid the problem of * having a the macro work as an expression by bundling an "err_instr". So; * * if (!dsa->meth->bn_mod_exp(dsa, r,dsa->g,&k,dsa->p,ctx, * dsa->method_mont_p)) goto err; * * can be replaced by; * * DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, &k, dsa->p, ctx, * dsa->method_mont_p); */ #define DSA_MOD_EXP(err_instr,dsa,rr,a1,p1,a2,p2,m,ctx,in_mont) \ do { \ int _tmp_res53; \ if((dsa)->meth->dsa_mod_exp) \ _tmp_res53 = (dsa)->meth->dsa_mod_exp((dsa), (rr), (a1), (p1), \ (a2), (p2), (m), (ctx), (in_mont)); \ else \ _tmp_res53 = BN_mod_exp2_mont((rr), (a1), (p1), (a2), (p2), \ (m), (ctx), (in_mont)); \ if(!_tmp_res53) err_instr; \ } while(0) #define DSA_BN_MOD_EXP(err_instr,dsa,r,a,p,m,ctx,m_ctx) \ do { \ int _tmp_res53; \ if((dsa)->meth->bn_mod_exp) \ _tmp_res53 = (dsa)->meth->bn_mod_exp((dsa), (r), (a), (p), \ (m), (ctx), (m_ctx)); \ else \ _tmp_res53 = BN_mod_exp_mont((r), (a), (p), (m), (ctx), (m_ctx)); \ if(!_tmp_res53) err_instr; \ } while(0) const DSA_METHOD *DSA_OpenSSL(void) { return &openssl_dsa_meth; } static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa) { BIGNUM *kinv=NULL,*r=NULL,*s=NULL; BIGNUM m; BIGNUM xr; BN_CTX *ctx=NULL; int i,reason=ERR_R_BN_LIB; DSA_SIG *ret=NULL; BN_init(&m); BN_init(&xr); if (!dsa->p || !dsa->q || !dsa->g) { reason=DSA_R_MISSING_PARAMETERS; goto err; } s=BN_new(); if (s == NULL) goto err; i=BN_num_bytes(dsa->q); /* should be 20 */ if ((dlen > i) || (dlen > 50)) { reason=DSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE; goto err; } ctx=BN_CTX_new(); if (ctx == NULL) goto err; if ((dsa->kinv == NULL) || (dsa->r == NULL)) { if (!DSA_sign_setup(dsa,ctx,&kinv,&r)) goto err; } else { kinv=dsa->kinv; dsa->kinv=NULL; r=dsa->r; dsa->r=NULL; } if (BN_bin2bn(dgst,dlen,&m) == NULL) goto err; /* Compute s = inv(k) (m + xr) mod q */ if (!BN_mod_mul(&xr,dsa->priv_key,r,dsa->q,ctx)) goto err;/* s = xr */ if (!BN_add(s, &xr, &m)) goto err; /* s = m + xr */ if (BN_cmp(s,dsa->q) > 0) BN_sub(s,s,dsa->q); if (!BN_mod_mul(s,s,kinv,dsa->q,ctx)) goto err; ret=DSA_SIG_new(); if (ret == NULL) goto err; ret->r = r; ret->s = s; err: if (!ret) { DSAerr(DSA_F_DSA_DO_SIGN,reason); BN_free(r); BN_free(s); } if (ctx != NULL) BN_CTX_free(ctx); BN_clear_free(&m); BN_clear_free(&xr); if (kinv != NULL) /* dsa->kinv is NULL now if we used it */ BN_clear_free(kinv); return(ret); } static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp) { BN_CTX *ctx; BIGNUM k,kq,*K,*kinv=NULL,*r=NULL; int ret=0; if (!dsa->p || !dsa->q || !dsa->g) { DSAerr(DSA_F_DSA_SIGN_SETUP,DSA_R_MISSING_PARAMETERS); return 0; } BN_init(&k); BN_init(&kq); if (ctx_in == NULL) { if ((ctx=BN_CTX_new()) == NULL) goto err; } else ctx=ctx_in; if ((r=BN_new()) == NULL) goto err; /* Get random k */ do if (!BN_rand_range(&k, dsa->q)) goto err; while (BN_is_zero(&k)); if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) { BN_set_flags(&k, BN_FLG_EXP_CONSTTIME); } if (dsa->flags & DSA_FLAG_CACHE_MONT_P) { if (!BN_MONT_CTX_set_locked(&dsa->method_mont_p, CRYPTO_LOCK_DSA, dsa->p, ctx)) goto err; } /* Compute r = (g^k mod p) mod q */ if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) { if (!BN_copy(&kq, &k)) goto err; /* We do not want timing information to leak the length of k, * so we compute g^k using an equivalent exponent of fixed length. * * (This is a kludge that we need because the BN_mod_exp_mont() * does not let us specify the desired timing behaviour.) */ if (!BN_add(&kq, &kq, dsa->q)) goto err; if (BN_num_bits(&kq) <= BN_num_bits(dsa->q)) { if (!BN_add(&kq, &kq, dsa->q)) goto err; } K = &kq; } else { K = &k; } DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, K, dsa->p, ctx, dsa->method_mont_p); if (!BN_mod(r,r,dsa->q,ctx)) goto err; /* Compute part of 's = inv(k) (m + xr) mod q' */ if ((kinv=BN_mod_inverse(NULL,&k,dsa->q,ctx)) == NULL) goto err; if (*kinvp != NULL) BN_clear_free(*kinvp); *kinvp=kinv; kinv=NULL; if (*rp != NULL) BN_clear_free(*rp); *rp=r; ret=1; err: if (!ret) { DSAerr(DSA_F_DSA_SIGN_SETUP,ERR_R_BN_LIB); if (kinv != NULL) BN_clear_free(kinv); if (r != NULL) BN_clear_free(r); } if (ctx_in == NULL) BN_CTX_free(ctx); if (kinv != NULL) BN_clear_free(kinv); BN_clear_free(&k); BN_clear_free(&kq); return(ret); } static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig, DSA *dsa) { BN_CTX *ctx; BIGNUM u1,u2,t1; BN_MONT_CTX *mont=NULL; int ret = -1; if (!dsa->p || !dsa->q || !dsa->g) { DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MISSING_PARAMETERS); return -1; } BN_init(&u1); BN_init(&u2); BN_init(&t1); if ((ctx=BN_CTX_new()) == NULL) goto err; if (BN_is_zero(sig->r) || BN_is_negative(sig->r) || BN_ucmp(sig->r, dsa->q) >= 0) { ret = 0; goto err; } if (BN_is_zero(sig->s) || BN_is_negative(sig->s) || BN_ucmp(sig->s, dsa->q) >= 0) { ret = 0; goto err; } /* Calculate W = inv(S) mod Q * save W in u2 */ if ((BN_mod_inverse(&u2,sig->s,dsa->q,ctx)) == NULL) goto err; /* save M in u1 */ if (BN_bin2bn(dgst,dgst_len,&u1) == NULL) goto err; /* u1 = M * w mod q */ if (!BN_mod_mul(&u1,&u1,&u2,dsa->q,ctx)) goto err; /* u2 = r * w mod q */ if (!BN_mod_mul(&u2,sig->r,&u2,dsa->q,ctx)) goto err; if (dsa->flags & DSA_FLAG_CACHE_MONT_P) { mont = BN_MONT_CTX_set_locked(&dsa->method_mont_p, CRYPTO_LOCK_DSA, dsa->p, ctx); if (!mont) goto err; } DSA_MOD_EXP(goto err, dsa, &t1, dsa->g, &u1, dsa->pub_key, &u2, dsa->p, ctx, mont); /* BN_copy(&u1,&t1); */ /* let u1 = u1 mod q */ if (!BN_mod(&u1,&t1,dsa->q,ctx)) goto err; /* V is now in u1. If the signature is correct, it will be * equal to R. */ ret=(BN_ucmp(&u1, sig->r) == 0); err: /* XXX: surely this is wrong - if ret is 0, it just didn't verify; there is no error in BN. Test should be ret == -1 (Ben) */ if (ret != 1) DSAerr(DSA_F_DSA_DO_VERIFY,ERR_R_BN_LIB); if (ctx != NULL) BN_CTX_free(ctx); BN_free(&u1); BN_free(&u2); BN_free(&t1); return(ret); } static int dsa_init(DSA *dsa) { dsa->flags|=DSA_FLAG_CACHE_MONT_P; return(1); } static int dsa_finish(DSA *dsa) { if(dsa->method_mont_p) BN_MONT_CTX_free(dsa->method_mont_p); return(1); } '>234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295