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From 8dbe0dc3eea5c689d4f76b37b93fe216cf1f00d4 Mon Sep 17 00:00:00 2001
From: Legrandin <helderijs@gmail.com>
Date: Sun, 22 Dec 2013 22:24:46 +0100
Subject: [PATCH] Throw exception when IV is used with ECB or CTR
The IV parameter is currently ignored when initializing
a cipher in ECB or CTR mode.
For CTR mode, it is confusing: it takes some time to see
that a different parameter is needed (the counter).
For ECB mode, it is outright dangerous.
This patch forces an exception to be raised.
Upstream-Status: Backport
[https://github.com/dlitz/pycrypto/commit/8dbe0dc3eea5c689d4f76b37b93fe216cf1f00d4]
CVE: CVE-2013-7459
Signed-off-by: Yi Zhao <yi.zhao@windriver.com>
---
lib/Crypto/SelfTest/Cipher/common.py | 31 +++++++++++++++++++++++--------
src/block_template.c | 11 +++++++++++
2 files changed, 34 insertions(+), 8 deletions(-)
diff --git a/lib/Crypto/SelfTest/Cipher/common.py b/lib/Crypto/SelfTest/Cipher/common.py
index 8bebed9..91ec743 100644
--- a/lib/Crypto/SelfTest/Cipher/common.py
+++ b/lib/Crypto/SelfTest/Cipher/common.py
@@ -239,19 +239,34 @@ class RoundtripTest(unittest.TestCase):
return """%s .decrypt() output of .encrypt() should not be garbled""" % (self.module_name,)
def runTest(self):
- for mode in (self.module.MODE_ECB, self.module.MODE_CBC, self.module.MODE_CFB, self.module.MODE_OFB, self.module.MODE_OPENPGP):
+
+ ## ECB mode
+ mode = self.module.MODE_ECB
+ encryption_cipher = self.module.new(a2b_hex(self.key), mode)
+ ciphertext = encryption_cipher.encrypt(self.plaintext)
+ decryption_cipher = self.module.new(a2b_hex(self.key), mode)
+ decrypted_plaintext = decryption_cipher.decrypt(ciphertext)
+ self.assertEqual(self.plaintext, decrypted_plaintext)
+
+ ## OPENPGP mode
+ mode = self.module.MODE_OPENPGP
+ encryption_cipher = self.module.new(a2b_hex(self.key), mode, self.iv)
+ eiv_ciphertext = encryption_cipher.encrypt(self.plaintext)
+ eiv = eiv_ciphertext[:self.module.block_size+2]
+ ciphertext = eiv_ciphertext[self.module.block_size+2:]
+ decryption_cipher = self.module.new(a2b_hex(self.key), mode, eiv)
+ decrypted_plaintext = decryption_cipher.decrypt(ciphertext)
+ self.assertEqual(self.plaintext, decrypted_plaintext)
+
+ ## All other non-AEAD modes (but CTR)
+ for mode in (self.module.MODE_CBC, self.module.MODE_CFB, self.module.MODE_OFB):
encryption_cipher = self.module.new(a2b_hex(self.key), mode, self.iv)
ciphertext = encryption_cipher.encrypt(self.plaintext)
-
- if mode != self.module.MODE_OPENPGP:
- decryption_cipher = self.module.new(a2b_hex(self.key), mode, self.iv)
- else:
- eiv = ciphertext[:self.module.block_size+2]
- ciphertext = ciphertext[self.module.block_size+2:]
- decryption_cipher = self.module.new(a2b_hex(self.key), mode, eiv)
+ decryption_cipher = self.module.new(a2b_hex(self.key), mode, self.iv)
decrypted_plaintext = decryption_cipher.decrypt(ciphertext)
self.assertEqual(self.plaintext, decrypted_plaintext)
+
class PGPTest(unittest.TestCase):
def __init__(self, module, params):
unittest.TestCase.__init__(self)
diff --git a/src/block_template.c b/src/block_template.c
index c36b316..8746948 100644
--- a/src/block_template.c
+++ b/src/block_template.c
@@ -170,6 +170,17 @@ ALGnew(PyObject *self, PyObject *args, PyObject *kwdict)
"Key cannot be the null string");
return NULL;
}
+ if (IVlen != 0 && mode == MODE_ECB)
+ {
+ PyErr_Format(PyExc_ValueError, "ECB mode does not use IV");
+ return NULL;
+ }
+ if (IVlen != 0 && mode == MODE_CTR)
+ {
+ PyErr_Format(PyExc_ValueError,
+ "CTR mode needs counter parameter, not IV");
+ return NULL;
+ }
if (IVlen != BLOCK_SIZE && mode != MODE_ECB && mode != MODE_CTR)
{
PyErr_Format(PyExc_ValueError,
--
2.7.4
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