diff options
| -rw-r--r-- | dss.c | 8 |
1 files changed, 8 insertions, 0 deletions
@@ -181,6 +181,10 @@ int buf_dss_verify(buffer* buf, dropbear_dss_key *key, buffer *data_buf) { TRACE(("verify failed, s' >= q")) goto out; } + if (mp_cmp_d(&val1, 0) != MP_GT) { + TRACE(("verify failed, s' <= 0")) + goto out; + } /* let val2 = w = (s')^-1 mod q*/ if (mp_invmod(&val1, key->q, &val2) != MP_OKAY) { goto out; @@ -202,6 +206,10 @@ int buf_dss_verify(buffer* buf, dropbear_dss_key *key, buffer *data_buf) { TRACE(("verify failed, r' >= q")) goto out; } + if (mp_cmp_d(&val1, 0) != MP_GT) { + TRACE(("verify failed, r' <= 0")) + goto out; + } /* let val4 = u2 = ((r')w) mod q */ if (mp_mulmod(&val1, &val2, key->q, &val4) != MP_OKAY) { goto out; |