/* 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 #ifndef FIPS 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 int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1, BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont); static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p, const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx); static DSA_METHOD openssl_dsa_meth = { "OpenSSL DSA method", dsa_do_sign, dsa_sign_setup, dsa_do_verify, dsa_mod_exp, dsa_bn_mod_exp, dsa_init, dsa_finish, 0, NULL }; 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,*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); if (ctx_in == NULL) { if ((ctx=BN_CTX_new()) == NULL) goto err; } else ctx=ctx_in; if ((r=BN_new()) == NULL) goto err; kinv=NULL; /* Get random k */ do if (!BN_rand_range(&k, dsa->q)) goto err; while (BN_is_zero(&k)); if ((dsa->method_mont_p == NULL) && (dsa->flags & DSA_FLAG_CACHE_MONT_P)) { if ((dsa->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL) if (!BN_MONT_CTX_set((BN_MONT_CTX *)dsa->method_mont_p, dsa->p,ctx)) goto err; } /* Compute r = (g^k mod p) mod q */ if (!dsa->meth->bn_mod_exp(dsa, r,dsa->g,&k,dsa->p,ctx, (BN_MONT_CTX *)dsa->method_mont_p)) goto err; 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); 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) || sig->r->neg || BN_ucmp(sig->r, dsa->q) >= 0) { ret = 0; goto err; } if (BN_is_zero(sig->s) || sig->s->neg || 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->method_mont_p == NULL) && (dsa->flags & DSA_FLAG_CACHE_MONT_P)) { if ((dsa->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL) if (!BN_MONT_CTX_set((BN_MONT_CTX *)dsa->method_mont_p, dsa->p,ctx)) goto err; } mont=(BN_MONT_CTX *)dsa->method_mont_p; #if 0 { BIGNUM t2; BN_init(&t2); /* v = ( g^u1 * y^u2 mod p ) mod q */ /* let t1 = g ^ u1 mod p */ if (!BN_mod_exp_mont(&t1,dsa->g,&u1,dsa->p,ctx,mont)) goto err; /* let t2 = y ^ u2 mod p */ if (!BN_mod_exp_mont(&t2,dsa->pub_key,&u2,dsa->p,ctx,mont)) goto err; /* let u1 = t1 * t2 mod p */ if (!BN_mod_mul(&u1,&t1,&t2,dsa->p,ctx)) goto err_bn; BN_free(&t2); } /* let u1 = u1 mod q */ if (!BN_mod(&u1,&u1,dsa->q,ctx)) goto err; #else { if (!dsa->meth->dsa_mod_exp(dsa, &t1,dsa->g,&u1,dsa->pub_key,&u2, dsa->p,ctx,mont)) goto err; /* BN_copy(&u1,&t1); */ /* let u1 = u1 mod q */ if (!BN_mod(&u1,&t1,dsa->q,ctx)) goto err; } #endif /* V is now in u1. If the signature is correct, it will be * equal to R. */ ret=(BN_ucmp(&u1, sig->r) == 0); err: 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((BN_MONT_CTX *)dsa->method_mont_p); return(1); } static int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1, BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont) { return BN_mod_exp2_mont(rr, a1, p1, a2, p2, m, ctx, in_mont); } static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p, const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx) { return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx); } #endif