diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/cryptography/hazmat/backends/openssl/ciphers.py | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/src/cryptography/hazmat/backends/openssl/ciphers.py b/src/cryptography/hazmat/backends/openssl/ciphers.py index 0f96795fd..50cbeb69a 100644 --- a/src/cryptography/hazmat/backends/openssl/ciphers.py +++ b/src/cryptography/hazmat/backends/openssl/ciphers.py @@ -145,7 +145,13 @@ class _CipherContext(object): res = self._backend._lib.EVP_CipherUpdate( self._ctx, outbuf, outlen, inbuf, inlen ) - self._backend.openssl_assert(res != 0) + if res == 0 and isinstance(self._mode, modes.XTS): + raise ValueError( + "In XTS mode you must supply at least a full block in the " + "first update call. For AES this is 16 bytes." + ) + else: + self._backend.openssl_assert(res != 0) data_processed += inlen total_out += outlen[0] |