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authorPaul Kehrer <paul.l.kehrer@gmail.com>2018-07-17 21:49:03 +0800
committerAlex Gaynor <alex.gaynor@gmail.com>2018-07-17 09:49:03 -0400
commitd4378e42937b56f473ddade2667f919ce32208cb (patch)
treef2374c70935a8b64e3b13d2d89314675d71cdeee /src/cryptography/hazmat/backends/openssl/ciphers.py
parentc574e7554c7aa27c56f6478258a4e18f79457652 (diff)
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disallow implicit tag truncation with finalize_with_tag (#4342)
Diffstat (limited to 'src/cryptography/hazmat/backends/openssl/ciphers.py')
-rw-r--r--src/cryptography/hazmat/backends/openssl/ciphers.py5
1 files changed, 5 insertions, 0 deletions
diff --git a/src/cryptography/hazmat/backends/openssl/ciphers.py b/src/cryptography/hazmat/backends/openssl/ciphers.py
index 462ffea2..e0ee06ee 100644
--- a/src/cryptography/hazmat/backends/openssl/ciphers.py
+++ b/src/cryptography/hazmat/backends/openssl/ciphers.py
@@ -199,6 +199,11 @@ class _CipherContext(object):
"finalize_with_tag requires OpenSSL >= 1.0.2. To use this "
"method please update OpenSSL"
)
+ if len(tag) < self._mode._min_tag_length:
+ raise ValueError(
+ "Authentication tag must be {0} bytes or longer.".format(
+ self._mode._min_tag_length)
+ )
res = self._backend._lib.EVP_CIPHER_CTX_ctrl(
self._ctx, self._backend._lib.EVP_CTRL_AEAD_SET_TAG,
len(tag), tag