88 lines
3.7 KiB
Diff
88 lines
3.7 KiB
Diff
From 8dbe0dc3eea5c689d4f76b37b93fe216cf1f00d4 Mon Sep 17 00:00:00 2001
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From: Legrandin <helderijs@gmail.com>
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Date: Sun, 22 Dec 2013 22:24:46 +0100
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Subject: [PATCH] Throw exception when IV is used with ECB or CTR
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The IV parameter is currently ignored when initializing
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a cipher in ECB or CTR mode.
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For CTR mode, it is confusing: it takes some time to see
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that a different parameter is needed (the counter).
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For ECB mode, it is outright dangerous.
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This patch forces an exception to be raised.
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---
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lib/Crypto/SelfTest/Cipher/common.py | 31 +++++++++++++++++++++++--------
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src/block_template.c | 11 +++++++++++
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2 files changed, 34 insertions(+), 8 deletions(-)
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diff --git a/lib/Crypto/SelfTest/Cipher/common.py b/lib/Crypto/SelfTest/Cipher/common.py
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index 420b6ff..a5f8a88 100644
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--- a/lib/Crypto/SelfTest/Cipher/common.py
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+++ b/lib/Crypto/SelfTest/Cipher/common.py
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@@ -239,19 +239,34 @@ def shortDescription(self):
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return """%s .decrypt() output of .encrypt() should not be garbled""" % (self.module_name,)
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def runTest(self):
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- for mode in (self.module.MODE_ECB, self.module.MODE_CBC, self.module.MODE_CFB, self.module.MODE_OFB, self.module.MODE_OPENPGP):
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+
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+ ## ECB mode
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+ mode = self.module.MODE_ECB
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+ encryption_cipher = self.module.new(a2b_hex(self.key), mode)
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+ ciphertext = encryption_cipher.encrypt(self.plaintext)
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+ decryption_cipher = self.module.new(a2b_hex(self.key), mode)
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+ decrypted_plaintext = decryption_cipher.decrypt(ciphertext)
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+ self.assertEqual(self.plaintext, decrypted_plaintext)
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+
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+ ## OPENPGP mode
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+ mode = self.module.MODE_OPENPGP
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+ encryption_cipher = self.module.new(a2b_hex(self.key), mode, self.iv)
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+ eiv_ciphertext = encryption_cipher.encrypt(self.plaintext)
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+ eiv = eiv_ciphertext[:self.module.block_size+2]
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+ ciphertext = eiv_ciphertext[self.module.block_size+2:]
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+ decryption_cipher = self.module.new(a2b_hex(self.key), mode, eiv)
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+ decrypted_plaintext = decryption_cipher.decrypt(ciphertext)
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+ self.assertEqual(self.plaintext, decrypted_plaintext)
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+
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+ ## All other non-AEAD modes (but CTR)
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+ for mode in (self.module.MODE_CBC, self.module.MODE_CFB, self.module.MODE_OFB):
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encryption_cipher = self.module.new(a2b_hex(self.key), mode, self.iv)
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ciphertext = encryption_cipher.encrypt(self.plaintext)
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-
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- if mode != self.module.MODE_OPENPGP:
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- decryption_cipher = self.module.new(a2b_hex(self.key), mode, self.iv)
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- else:
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- eiv = ciphertext[:self.module.block_size+2]
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- ciphertext = ciphertext[self.module.block_size+2:]
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- decryption_cipher = self.module.new(a2b_hex(self.key), mode, eiv)
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+ decryption_cipher = self.module.new(a2b_hex(self.key), mode, self.iv)
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decrypted_plaintext = decryption_cipher.decrypt(ciphertext)
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self.assertEqual(self.plaintext, decrypted_plaintext)
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+
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class PGPTest(unittest.TestCase):
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def __init__(self, module, params):
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unittest.TestCase.__init__(self)
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diff --git a/src/block_template.c b/src/block_template.c
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index f940e0e..d555ceb 100644
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--- a/src/block_template.c
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+++ b/src/block_template.c
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@@ -170,6 +170,17 @@ ALGnew(PyObject *self, PyObject *args, PyObject *kwdict)
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"Key cannot be the null string");
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return NULL;
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}
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+ if (IVlen != 0 && mode == MODE_ECB)
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+ {
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+ PyErr_Format(PyExc_ValueError, "ECB mode does not use IV");
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+ return NULL;
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+ }
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+ if (IVlen != 0 && mode == MODE_CTR)
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+ {
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+ PyErr_Format(PyExc_ValueError,
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+ "CTR mode needs counter parameter, not IV");
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+ return NULL;
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+ }
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if (IVlen != BLOCK_SIZE && mode != MODE_ECB && mode != MODE_CTR)
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{
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PyErr_Format(PyExc_ValueError,
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