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/* crypto/dsa/dsa_ossl.c */
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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* This package is an SSL implementation written
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* by Eric Young (eay@cryptsoft.com).
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* The implementation was written so as to conform with Netscapes SSL.
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* This library is free for commercial and non-commercial use as long as
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* the following conditions are aheared to. The following conditions
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* apply to all code found in this distribution, be it the RC4, RSA,
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* lhash, DES, etc., code; not just the SSL code. The SSL documentation
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* included with this distribution is covered by the same copyright terms
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* except that the holder is Tim Hudson (tjh@cryptsoft.com).
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* Copyright remains Eric Young's, and as such any Copyright notices in
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* the code are not to be removed.
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* If this package is used in a product, Eric Young should be given attribution
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* as the author of the parts of the library used.
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* This can be in the form of a textual message at program startup or
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* in documentation (online or textual) provided with the package.
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* 1. Redistributions of source code must retain the copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* "This product includes cryptographic software written by
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* Eric Young (eay@cryptsoft.com)"
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* The word 'cryptographic' can be left out if the rouines from the library
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* being used are not cryptographic related :-).
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* 4. If you include any Windows specific code (or a derivative thereof) from
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* the apps directory (application code) you must include an acknowledgement:
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* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
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* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* The licence and distribution terms for any publically available version or
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* derivative of this code cannot be changed. i.e. this code cannot simply be
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* copied and put under another distribution licence
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* [including the GNU Public Licence.]
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/* Original version from Steven Schoch <schoch@sheba.arc.nasa.gov> */
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#include <openssl/bn.h>
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#include <openssl/dsa.h>
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#include <openssl/rand.h>
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#include <openssl/asn1.h>
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#include <openssl/err.h>
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#ifndef OPENSSL_NO_ENGINE
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#include <openssl/engine.h>
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#include <openssl/fips.h>
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static DSA_SIG *dsa_do_sign(const unsigned char *dgst, FIPS_DSA_SIZE_T dlen, DSA *dsa);
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static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp);
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static int dsa_do_verify(const unsigned char *dgst, FIPS_DSA_SIZE_T dgst_len, DSA_SIG *sig,
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static int dsa_init(DSA *dsa);
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static int dsa_finish(DSA *dsa);
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static int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
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BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx,
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BN_MONT_CTX *in_mont);
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static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
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const BIGNUM *m, BN_CTX *ctx,
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static const DSA_METHOD openssl_dsa_meth = {
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"OpenSSL FIPS DSA method",
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int FIPS_dsa_check(struct dsa_st *dsa)
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if(dsa->meth != &openssl_dsa_meth || dsa->meth->dsa_do_sign != dsa_do_sign
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|| dsa->meth->dsa_sign_setup != dsa_sign_setup
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|| dsa->meth->dsa_mod_exp != dsa_mod_exp
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|| dsa->meth->bn_mod_exp != dsa_bn_mod_exp
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|| dsa->meth->init != dsa_init
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|| dsa->meth->finish != dsa_finish)
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FIPSerr(FIPS_F_FIPS_DSA_CHECK,FIPS_R_NON_FIPS_METHOD);
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const DSA_METHOD *DSA_OpenSSL(void)
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return &openssl_dsa_meth;
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static DSA_SIG *dsa_do_sign(const unsigned char *dgst, FIPS_DSA_SIZE_T dlen, DSA *dsa)
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BIGNUM *kinv=NULL,*r=NULL,*s=NULL;
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int i,reason=ERR_R_BN_LIB;
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if(FIPS_selftest_failed())
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FIPSerr(FIPS_F_DSA_DO_SIGN,FIPS_R_FIPS_SELFTEST_FAILED);
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if (FIPS_mode() && (BN_num_bits(dsa->p) < OPENSSL_DSA_FIPS_MIN_MODULUS_BITS))
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DSAerr(DSA_F_DSA_DO_SIGN, DSA_R_KEY_SIZE_TOO_SMALL);
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if (!dsa->p || !dsa->q || !dsa->g)
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reason=DSA_R_MISSING_PARAMETERS;
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if (s == NULL) goto err;
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i=BN_num_bytes(dsa->q); /* should be 20 */
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if ((dlen > i) || (dlen > 50))
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reason=DSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE;
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if (ctx == NULL) goto err;
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if (!dsa->meth->dsa_sign_setup(dsa,ctx,&kinv,&r)) goto err;
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if (BN_bin2bn(dgst,dlen,&m) == NULL) goto err;
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/* Compute s = inv(k) (m + xr) mod q */
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if (!BN_mod_mul(&xr,dsa->priv_key,r,dsa->q,ctx)) goto err;/* s = xr */
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if (!BN_add(s, &xr, &m)) goto err; /* s = m + xr */
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if (BN_cmp(s,dsa->q) > 0)
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if (!BN_mod_mul(s,s,kinv,dsa->q,ctx)) goto err;
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if (ret == NULL) goto err;
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DSAerr(DSA_F_DSA_DO_SIGN,reason);
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if (ctx != NULL) BN_CTX_free(ctx);
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if (kinv != NULL) /* dsa->kinv is NULL now if we used it */
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static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
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BIGNUM k,kq,*K,*kinv=NULL,*r=NULL;
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if (!dsa->p || !dsa->q || !dsa->g)
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DSAerr(DSA_F_DSA_SIGN_SETUP,DSA_R_MISSING_PARAMETERS);
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if ((ctx=BN_CTX_new()) == NULL) goto err;
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if ((r=BN_new()) == NULL) goto err;
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if (!BN_rand_range(&k, dsa->q)) goto err;
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while (BN_is_zero(&k));
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if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)
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BN_set_flags(&k, BN_FLG_CONSTTIME);
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if (dsa->flags & DSA_FLAG_CACHE_MONT_P)
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if (!BN_MONT_CTX_set_locked((BN_MONT_CTX **)&dsa->method_mont_p,
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/* Compute r = (g^k mod p) mod q */
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if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)
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if (!BN_copy(&kq, &k)) goto err;
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/* We do not want timing information to leak the length of k,
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* so we compute g^k using an equivalent exponent of fixed length.
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* (This is a kludge that we need because the BN_mod_exp_mont()
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* does not let us specify the desired timing behaviour.) */
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if (!BN_add(&kq, &kq, dsa->q)) goto err;
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if (BN_num_bits(&kq) <= BN_num_bits(dsa->q))
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if (!BN_add(&kq, &kq, dsa->q)) goto err;
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if (!dsa->meth->bn_mod_exp(dsa, r,dsa->g,K,dsa->p,ctx,
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(BN_MONT_CTX *)dsa->method_mont_p)) goto err;
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if (!BN_mod(r,r,dsa->q,ctx)) goto err;
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/* Compute part of 's = inv(k) (m + xr) mod q' */
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if ((kinv=BN_mod_inverse(NULL,&k,dsa->q,ctx)) == NULL) goto err;
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if (*kinvp != NULL) BN_clear_free(*kinvp);
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if (*rp != NULL) BN_clear_free(*rp);
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DSAerr(DSA_F_DSA_SIGN_SETUP,ERR_R_BN_LIB);
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if (kinv != NULL) BN_clear_free(kinv);
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if (r != NULL) BN_clear_free(r);
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if (ctx_in == NULL) BN_CTX_free(ctx);
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if (kinv != NULL) BN_clear_free(kinv);
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static int dsa_do_verify(const unsigned char *dgst, FIPS_DSA_SIZE_T dgst_len, DSA_SIG *sig,
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BN_MONT_CTX *mont=NULL;
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if (!dsa->p || !dsa->q || !dsa->g)
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DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MISSING_PARAMETERS);
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if(FIPS_selftest_failed())
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FIPSerr(FIPS_F_DSA_DO_VERIFY,FIPS_R_FIPS_SELFTEST_FAILED);
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if (BN_num_bits(dsa->q) != 160)
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DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_BAD_Q_VALUE);
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if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS)
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DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MODULUS_TOO_LARGE);
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if (FIPS_mode() && (BN_num_bits(dsa->p) < OPENSSL_DSA_FIPS_MIN_MODULUS_BITS))
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DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_KEY_SIZE_TOO_SMALL);
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if ((ctx=BN_CTX_new()) == NULL) goto err;
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if (BN_is_zero(sig->r) || sig->r->neg || BN_ucmp(sig->r, dsa->q) >= 0)
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if (BN_is_zero(sig->s) || sig->s->neg || BN_ucmp(sig->s, dsa->q) >= 0)
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/* Calculate W = inv(S) mod Q
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if ((BN_mod_inverse(&u2,sig->s,dsa->q,ctx)) == NULL) goto err;
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if (BN_bin2bn(dgst,dgst_len,&u1) == NULL) goto err;
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/* u1 = M * w mod q */
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if (!BN_mod_mul(&u1,&u1,&u2,dsa->q,ctx)) goto err;
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/* u2 = r * w mod q */
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if (!BN_mod_mul(&u2,sig->r,&u2,dsa->q,ctx)) goto err;
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if (dsa->flags & DSA_FLAG_CACHE_MONT_P)
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mont = BN_MONT_CTX_set_locked(
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(BN_MONT_CTX **)&dsa->method_mont_p,
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CRYPTO_LOCK_DSA, dsa->p, ctx);
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/* v = ( g^u1 * y^u2 mod p ) mod q */
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/* let t1 = g ^ u1 mod p */
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if (!BN_mod_exp_mont(&t1,dsa->g,&u1,dsa->p,ctx,mont)) goto err;
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/* let t2 = y ^ u2 mod p */
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if (!BN_mod_exp_mont(&t2,dsa->pub_key,&u2,dsa->p,ctx,mont)) goto err;
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/* let u1 = t1 * t2 mod p */
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if (!BN_mod_mul(&u1,&t1,&t2,dsa->p,ctx)) goto err_bn;
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/* let u1 = u1 mod q */
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if (!BN_mod(&u1,&u1,dsa->q,ctx)) goto err;
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if (!dsa->meth->dsa_mod_exp(dsa, &t1,dsa->g,&u1,dsa->pub_key,&u2,
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dsa->p,ctx,mont)) goto err;
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/* BN_copy(&u1,&t1); */
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/* let u1 = u1 mod q */
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if (!BN_mod(&u1,&t1,dsa->q,ctx)) goto err;
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/* V is now in u1. If the signature is correct, it will be
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ret=(BN_ucmp(&u1, sig->r) == 0);
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if (ret != 1) DSAerr(DSA_F_DSA_DO_VERIFY,ERR_R_BN_LIB);
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if (ctx != NULL) BN_CTX_free(ctx);
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static int dsa_init(DSA *dsa)
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FIPS_selftest_check();
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dsa->flags|=DSA_FLAG_CACHE_MONT_P;
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static int dsa_finish(DSA *dsa)
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if(dsa->method_mont_p)
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BN_MONT_CTX_free((BN_MONT_CTX *)dsa->method_mont_p);
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static int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
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BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx,
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BN_MONT_CTX *in_mont)
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return BN_mod_exp2_mont(rr, a1, p1, a2, p2, m, ctx, in_mont);
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static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
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const BIGNUM *m, BN_CTX *ctx,
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return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
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#else /* ndef OPENSSL_FIPS */
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static void *dummy=&dummy;
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#endif /* ndef OPENSSL_FIPS */