avoid shifting input

[openssl.git] / crypto / dsa / dsa_ossl.c

diff --git a/crypto/dsa/dsa_ossl.c b/crypto/dsa/dsa_ossl.c
index 96df46b70dcb69d8caddebb2600fc517b2cc75d7..38004eced5cac6134ac7177ce5076e73e98b6df0 100644 (file)
--- a/crypto/dsa/dsa_ossl.c
+++ b/crypto/dsa/dsa_ossl.c
@@ -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, j, 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))
-                       goto err; 
-               }
+               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;