--- /dev/null
+/* 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 <schoch@sheba.arc.nasa.gov> */
+
+#include <stdio.h>
+#include "cryptlib.h"
+#include <openssl/bn.h>
+#include <openssl/sha.h>
+#include <openssl/dsa.h>
+#include <openssl/rand.h>
+#include <openssl/asn1.h>
+
+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 reason=ERR_R_BN_LIB;
+ DSA_SIG *ret=NULL;
+ int noredo = 0;
+
+ 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;
+ ctx=BN_CTX_new();
+ if (ctx == NULL) goto err;
+redo:
+ 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;
+ noredo = 1;
+ }
+
+
+ if (dlen > BN_num_bytes(dsa->q))
+ /* if the digest length is greater than the size of q use the
+ * BN_num_bits(dsa->q) leftmost bits of the digest, see
+ * fips 186-3, 4.2 */
+ dlen = BN_num_bytes(dsa->q);
+ 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)
+ if (!BN_sub(s,s,dsa->q)) goto err;
+ if (!BN_mod_mul(s,s,kinv,dsa->q,ctx)) goto err;
+
+ ret=DSA_SIG_new();
+ if (ret == NULL) goto err;
+ /* Redo if r or s is zero as required by FIPS 186-3: this is
+ * very unlikely.
+ */
+ if (BN_is_zero(r) || BN_is_zero(s))
+ {
+ if (noredo)
+ {
+ reason = DSA_R_NEED_NEW_SETUP_VALUES;
+ goto err;
+ }
+ goto redo;
+ }
+ 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_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 (r != NULL)
+ BN_clear_free(r);
+ }
+ if (ctx_in == NULL) BN_CTX_free(ctx);
+ 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, i;
+ if (!dsa->p || !dsa->q || !dsa->g)
+ {
+ DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MISSING_PARAMETERS);
+ return -1;
+ }
+
+ i = BN_num_bits(dsa->q);
+ /* fips 186-3 allows only different sizes for q */
+ if (i != 160 && i != 224 && i != 256)
+ {
+ DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_BAD_Q_VALUE);
+ return -1;
+ }
+
+ if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS)
+ {
+ DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MODULUS_TOO_LARGE);
+ 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 (dgst_len > (i >> 3))
+ /* if the digest length is greater than the size of q use the
+ * BN_num_bits(dsa->q) leftmost bits of the digest, see
+ * fips 186-3, 4.2 */
+ dgst_len = (i >> 3);
+ 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);
+}
+
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