1 files changed, 24 insertions, 30 deletions

diff --git a/src/lib/libcrypto/ecdsa/ecs_ossl.c b/src/lib/libcrypto/ecdsa/ecs_ossl.c
index 3ead1af94e..551cf5068f 100644
--- a/src/lib/libcrypto/ecdsa/ecs_ossl.c
+++ b/src/lib/libcrypto/ecdsa/ecs_ossl.c
@@ -212,7 +212,7 @@ err:
 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len, 
                 const BIGNUM *in_kinv, const BIGNUM *in_r, EC_KEY *eckey)
 {
-        int     ok = 0;
+        int     ok = 0, i;
         BIGNUM *kinv=NULL, *s, *m=NULL,*tmp=NULL,*order=NULL;
         const BIGNUM *ckinv;
         BN_CTX     *ctx = NULL;
@@ -251,22 +251,19 @@ static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len,
                 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_EC_LIB);
                 goto err;
         }
-        if (8 * dgst_len > BN_num_bits(order))
+        i = BN_num_bits(order);
+        /* Need to truncate digest if it is too long: first truncate whole
+         * bytes.
+         */
+        if (8 * dgst_len > i)
+                dgst_len = (i + 7)/8;
+        if (!BN_bin2bn(dgst, dgst_len, m))
         {
-                /* XXX
-                 * 
-                 * Should provide for optional hash truncation:
-                 * Keep the BN_num_bits(order) leftmost bits of dgst
-                 * (see March 2006 FIPS 186-3 draft, which has a few
-                 * confusing errors in this part though)
-                 */
-
-                ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,
-                        ECDSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
+                ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
                 goto err;
         }
-
-        if (!BN_bin2bn(dgst, dgst_len, m))
+        /* If still too long truncate remaining bits with a shift */
+        if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7)))
         {
                 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
                 goto err;
@@ -346,7 +343,7 @@ err:
 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
                 const ECDSA_SIG *sig, EC_KEY *eckey)
 {
-        int ret = -1;
+        int ret = -1, i;
         BN_CTX   *ctx;
         BIGNUM   *order, *u1, *u2, *m, *X;
         EC_POINT *point = NULL;
@@ -384,21 +381,6 @@ static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
                 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
                 goto err;
         }
-        if (8 * dgst_len > BN_num_bits(order))
-        {
-                /* XXX
-                 * 
-                 * Should provide for optional hash truncation:
-                 * Keep the BN_num_bits(order) leftmost bits of dgst
-                 * (see March 2006 FIPS 186-3 draft, which has a few
-                 * confusing errors in this part though)
-                 */
-
-                ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY,
-                        ECDSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
-                ret = 0;
-                goto err;
-        }
 
         if (BN_is_zero(sig->r)          || BN_is_negative(sig->r) || 
             BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s)  ||
@@ -415,11 +397,23 @@ static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
                 goto err;
         }
         /* digest -> m */
+        i = BN_num_bits(order);
+        /* Need to truncate digest if it is too long: first truncate whole
+         * bytes.
+         */
+        if (8 * dgst_len > i)
+                dgst_len = (i + 7)/8;
         if (!BN_bin2bn(dgst, dgst_len, m))
         {
                 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
                 goto err;
         }
+        /* If still too long truncate remaining bits with a shift */
+        if ((8 * dgst_len > i) && !BN_rshift(m, m, 8 - (i & 0x7)))
+        {
+                ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
+                goto err;
+        }
         /* u1 = m * tmp mod order */
         if (!BN_mod_mul(u1, m, u2, order, ctx))
         {