use M2Crypto

encrypt.py

@@ -0,0 +1,127 @@
+#!/usr/bin/env python
+
+# Copyright (c) 2012 clowwindy
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# 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.
+
+import sys
+import hashlib
+import string
+import struct
+import logging
+
+
+def get_table(key):
+    m = hashlib.md5()
+    m.update(key)
+    s = m.digest()
+    (a, b) = struct.unpack('<QQ', s)
+    table = [c for c in string.maketrans('', '')]
+    for i in xrange(1, 1024):
+        table.sort(lambda x, y: int(a % (ord(x) + i) - a % (ord(y) + i)))
+    return table
+
+encrypt_table = None
+decrypt_table = None
+
+
+def init_table(key, method=None):
+    if method == 'table':
+        method = None
+    if method:
+        try:
+            __import__('M2Crypto')
+        except ImportError:
+            logging.error('M2Crypto is required to use encryption other than default method')
+            sys.exit(1)
+    if not method:
+        global encrypt_table, decrypt_table
+        encrypt_table = ''.join(get_table(key))
+        decrypt_table = string.maketrans(encrypt_table, string.maketrans('', ''))
+    else:
+        get_cipher(key, method, 1)
+
+
+def EVP_BytesToKey(password, key_len, iv_len):
+    # equivalent to OpenSSL's EVP_BytesToKey() with count 1
+    # so that we make the same key and iv as nodejs version
+    # TODO: cache the results
+    m = []
+    i = 0
+    while len(''.join(m)) < (key_len + iv_len):
+        md5 = hashlib.md5()
+        data = password
+        if i > 0:
+            data = m[i - 1] + password
+        md5.update(data)
+        m.append(md5.digest())
+        i += 1
+    ms = ''.join(m)
+    key = ms[:key_len]
+    iv = ms[key_len:key_len + iv_len]
+    return (key, iv)
+
+
+method_supported = {
+    'aes-128-cfb': (16, 16),
+    'aes-192-cfb': (24, 16),
+    'aes-256-cfb': (32, 16),
+    'bf-cfb': (16, 8),
+    'cast5-cfb': (16, 8),
+    'des-cfb': (8, 8),
+    'rc4': (16, 0),
+}
+
+
+def get_cipher(password, method, op):
+    import M2Crypto.EVP
+    password = password.encode('utf-8')
+    method = method.lower()
+    m = method_supported.get(method, None)
+    if m:
+        key, iv = EVP_BytesToKey(password, m[0], m[1])
+        return M2Crypto.EVP.Cipher(method.replace('-', '_'), key, iv, op, key_as_bytes=0, d='md5', salt=None, i=1, padding=1)
+
+    logging.error('method %s not supported' % method)
+    sys.exit(1)
+
+
+class Encryptor(object):
+    def __init__(self, key, method=None):
+        if method == 'table':
+            method = None
+        self.method = method
+        if method is not None:
+            self.cipher = get_cipher(key, method, 1)
+            self.decipher = get_cipher(key, method, 0)
+        else:
+            self.cipher = None
+            self.decipher = None
+
+    def encrypt(self, buf):
+        if self.cipher is None:
+            return string.translate(buf, encrypt_table)
+        else:
+            return self.cipher.update(buf)
+
+    def decrypt(self, buf):
+        if self.cipher is None:
+            return string.translate(buf, decrypt_table)
+        else:
+            return self.decipher.update(buf)