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-rw-r--r--lib/Crypto/Cipher/ARC4.py108
-rw-r--r--setup.py2
-rw-r--r--src/ARC4.c2
3 files changed, 110 insertions, 2 deletions
diff --git a/lib/Crypto/Cipher/ARC4.py b/lib/Crypto/Cipher/ARC4.py
new file mode 100644
index 0000000..de5e4e8
--- /dev/null
+++ b/lib/Crypto/Cipher/ARC4.py
@@ -0,0 +1,108 @@
+# -*- coding: utf-8 -*-
+#
+# Cipher/ARC4.py : ARC4
+#
+# ===================================================================
+# The contents of this file are dedicated to the public domain. To
+# the extent that dedication to the public domain is not available,
+# everyone is granted a worldwide, perpetual, royalty-free,
+# non-exclusive license to exercise all rights associated with the
+# contents of this file for any purpose whatsoever.
+# No rights are reserved.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+# ===================================================================
+"""ARC4 symmetric cipher
+
+ARC4_ (Alleged RC4) is an implementation of RC4 (Rivest's Cipher version 4),
+a symmetric stream cipher designed by Ron Rivest in 1987.
+
+The cipher started as a proprietary design, that was reverse engineered and
+anonymously posted on Usenet in 1994. The company that owns RC4 (RSA Data
+Inc.) never confirmed the correctness of the leaked algorithm.
+
+Unlike RC2, the company has never published the full specification of RC4,
+of whom it still holds the trademark.
+
+ARC4 keys can vary in length from 40 to 2048 bits.
+
+One problem of ARC4 is that it does not take a nonce or an IV. If it is required
+to encrypt multiple messages with the same long-term key, a distinct
+independent nonce must be created for each message, and a short-term key must
+be derived from the combination of the long-term key and the nonce.
+Due to the weak key scheduling algorithm of RC2, the combination must be carried
+out with a complex function (e.g. a cryptographic hash) and not by simply
+concatenating key and nonce.
+
+New designs should not use ARC4. A good alternative is AES
+(`Crypto.Cipher.AES`) in any of the modes that turn it into a stream cipher (OFB, CFB, or CTR).
+
+.. _ARC4: http://en.wikipedia.org/wiki/RC4
+
+:undocumented: __revision__, __package__
+"""
+
+__revision__ = "$Id$"
+
+from Crypto.Cipher import _ARC4
+
+class ARC4Cipher:
+ """ARC4 cipher object"""
+
+
+ def __init__(self, key, *args, **kwargs):
+ """Initialize an ARC4 cipher object
+
+ See also `new()` at the module level."""
+
+ self._cipher = _ARC4.new(key, *args, **kwargs)
+ self.block_size = self._cipher.block_size
+ self.key_size = self._cipher.key_size
+
+ def encrypt(self, plaintext):
+ """Encrypt a piece of data.
+
+ :Parameters:
+ plaintext : byte string
+ The piece of data to encrypt. It can be of any size.
+ :Return: the encrypted data (byte string, as long as the
+ plaintext).
+ """
+ return self._cipher.encrypt(plaintext)
+
+ def decrypt(self, ciphertext):
+ """Decrypt a piece of data.
+
+ :Parameters:
+ ciphertext : byte string
+ The piece of data to decrypt. It can be of any size.
+ :Return: the decrypted data (byte string, as long as the
+ ciphertext).
+ """
+ return self._cipher.decrypt(ciphertext)
+
+def new(key, *args, **kwargs):
+ """Create a new ARC4 cipher
+
+ :Parameters:
+ key : byte string
+ The secret key to use in the symmetric cipher.
+ It can have any length, with a minimum of 40 bytes.
+ Its cryptograpic strength is always capped to 2048 bits (256 bytes).
+
+ :Return: an `ARC4Cipher` object
+ """
+ return ARC4Cipher(key, *args, **kwargs)
+
+#: Size of a data block (in bytes)
+block_size = 1
+#: Size of a key (in bytes)
+key_size = xrange(1,256+1)
+
diff --git a/setup.py b/setup.py
index e656772..704280e 100644
--- a/setup.py
+++ b/setup.py
@@ -415,7 +415,7 @@ kw = {'name':"pycrypto",
sources=["src/DES3.c"]),
# Stream ciphers
- Extension("Crypto.Cipher.ARC4",
+ Extension("Crypto.Cipher._ARC4",
include_dirs=['src/'],
sources=["src/ARC4.c"]),
Extension("Crypto.Cipher.XOR",
diff --git a/src/ARC4.c b/src/ARC4.c
index 2a689e4..28dc4a3 100644
--- a/src/ARC4.c
+++ b/src/ARC4.c
@@ -26,7 +26,7 @@
*
*/
-#define MODULE_NAME ARC4
+#define MODULE_NAME _ARC4
#define BLOCK_SIZE 1
#define KEY_SIZE 0