Fix GCM counter reuse

GCM should error out after processing (2^32)-1 blocks / (2^39)-256 bits
2016-09-28 20:17:53 +02:00 · 2016-09-28 20:17:53 +02:00 · 7d418b34b3
commit 7d418b34b3
parent 6ad5225268
1 changed files with 5 additions and 0 deletions
--- a/src/encauth/gcm/gcm_process.c
+++ b/src/encauth/gcm/gcm_process.c
@ -49,6 +49,11 @@ int gcm_process(gcm_state *gcm,
      return err;
   }

+   /* 0xFFFFFFFE0 = ((2^39)-256)/8 */
+   if (gcm->pttotlen / 8 + (ulong64)gcm->buflen + (ulong64)ptlen >= CONST64(0xFFFFFFFE0)) {
+      return CRYPT_INVALID_ARG;
+   }
+
   /* in AAD mode? */
   if (gcm->mode == LTC_GCM_MODE_AAD) {
      /* let's process the AAD */