Commit b900a6b4 authored by Nils Larsch's avatar Nils Larsch
Browse files

avoid shifting input

parent 15780a1e

crypto/dsa/dsa_ossl.c

+10 −17
Original line number Diff line number Diff line
@@ -134,7 +134,7 @@ static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa) 
	BIGNUM m;

	BIGNUM xr;

	BN_CTX *ctx=NULL;

	int i, reason=ERR_R_BN_LIB;

	int reason=ERR_R_BN_LIB;

	DSA_SIG *ret=NULL;



	BN_init(&m);
@@ -172,17 +172,14 @@ static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa) 
		dsa->r=NULL;

		}



	if (BN_bin2bn(dgst,dlen,&m) == NULL)

		goto err;

	i = BN_num_bytes(dsa->q);

	if (dlen > i)

		{

	

	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 */

		if (!BN_rshift(&m, &m, (dlen - i) << 3))

		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 */
@@ -308,7 +305,7 @@ static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig, 
	BN_CTX *ctx;

	BIGNUM u1,u2,t1;

	BN_MONT_CTX *mont=NULL;

	int ret = -1, i, j;

	int ret = -1, i;

	if (!dsa->p || !dsa->q || !dsa->g)

		{

		DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MISSING_PARAMETERS);
@@ -361,16 +358,12 @@ static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig, 
	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;

	j = dgst_len << 3;

	if (j > i)

		{

	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 */

		if (!BN_rshift(&u1, &u1, j - i))

			goto err; 

		}

		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;