moved DES routines to separate module

1 files changed, 724 insertions, 0 deletions

diff --git a/passlib/utils/des.py b/passlib/utils/des.py
new file mode 100644
index 0000000..e899cd5
--- /dev/null
+++ b/passlib/utils/des.py
@@ -0,0 +1,724 @@
+"""passlib.utils.des -- DES encryption routines
+
+This module contains routines for encrypting blocks of data using the DES algorithm.
+
+They do not support multi-block operation or decryption,
+since they are designed for use in password hash algorithms
+such as ``lmhash`` and ``des-crypt``.
+
+.. function:: des_expand_key
+.. function:: des_encrypt_block
+.. function:: mdes_encrypt_int_block
+"""
+
+"""
+History
+=======
+These routines (which have since been drastically modified for python)
+are based on a Java implementation of the des-crypt algorithm,
+found at `<http://www.dynamic.net.au/christos/crypt/UnixCrypt2.txt>`_.
+
+The copyright & license for that source is as follows::
+
+    UnixCrypt.java	0.9 96/11/25
+    Copyright (c) 1996 Aki Yoshida. All rights reserved.
+    Permission to use, copy, modify and distribute this software
+    for non-commercial or commercial purposes and without fee is
+    hereby granted provided that this copyright notice appears in
+    all copies.
+
+    ---
+
+    Unix crypt(3C) utility
+    @version 	0.9, 11/25/96
+    @author 	Aki Yoshida
+
+    ---
+
+    modified April 2001
+    by Iris Van den Broeke, Daniel Deville
+
+    ---
+    Unix Crypt.
+    Implements the one way cryptography used by Unix systems for
+    simple password protection.
+    @version $Id: UnixCrypt2.txt,v 1.1.1.1 2005/09/13 22:20:13 christos Exp $
+    @author Greg Wilkins (gregw)
+"""
+#=========================================================
+#imports
+#=========================================================
+#pkg
+from passlib.utils import bytes_to_int, int_to_bytes
+#local
+__all__ = [
+    "expand_des_key",
+    "des_encrypt_block",
+    "mdes_encrypt_int_block",
+]
+
+#=========================================================
+#precalculated iteration ranges & constants
+#=========================================================
+R8 = range(8)
+RR8 = range(7, -1, -1)
+RR4 = range(3, -1, -1)
+RR12_1 = range(11, 1, -1)
+RR9_1 = range(9,-1,-1)
+
+RR6_S2 = range(6, -1, -2)
+RR14_S2 = range(14, -1, -2)
+R16_S2 = range(0, 16, 2)
+
+INT_24_MAX = 0xffffffL
+INT_64_MAX = 0xffffffffL
+INT_64_MAX = 0xffffffffffffffffL
+
+#=========================================================
+# static tables for des
+#=========================================================
+PCXROT = IE3264 = SPE = CF6464 = None #placeholders filled in by load_tables
+
+def load_tables():
+    "delay loading tables until they are actually needed"
+    global PCXROT, IE3264, SPE, CF6464
+
+    #---------------------------------------------------
+    # Initial key schedule permutation
+    # PC1ROT - bit reverse, then PC1, then Rotate, then PC2
+    #---------------------------------------------------
+    #NOTE: this was reordered from original table to make perm3264 logic simpler
+    PC1ROT=(
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000000000002000, 0x0000000000002000,
+      0x0000000000000020, 0x0000000000000020, 0x0000000000002020, 0x0000000000002020,
+      0x0000000000000400, 0x0000000000000400, 0x0000000000002400, 0x0000000000002400,
+      0x0000000000000420, 0x0000000000000420, 0x0000000000002420, 0x0000000000002420, ),
+    ( 0x0000000000000000, 0x2000000000000000, 0x0000000400000000, 0x2000000400000000,
+      0x0000800000000000, 0x2000800000000000, 0x0000800400000000, 0x2000800400000000,
+      0x0008000000000000, 0x2008000000000000, 0x0008000400000000, 0x2008000400000000,
+      0x0008800000000000, 0x2008800000000000, 0x0008800400000000, 0x2008800400000000, ),
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000000000000040, 0x0000000000000040,
+      0x0000000020000000, 0x0000000020000000, 0x0000000020000040, 0x0000000020000040,
+      0x0000000000200000, 0x0000000000200000, 0x0000000000200040, 0x0000000000200040,
+      0x0000000020200000, 0x0000000020200000, 0x0000000020200040, 0x0000000020200040, ),
+    ( 0x0000000000000000, 0x0002000000000000, 0x0800000000000000, 0x0802000000000000,
+      0x0100000000000000, 0x0102000000000000, 0x0900000000000000, 0x0902000000000000,
+      0x4000000000000000, 0x4002000000000000, 0x4800000000000000, 0x4802000000000000,
+      0x4100000000000000, 0x4102000000000000, 0x4900000000000000, 0x4902000000000000, ),
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000000000040000, 0x0000000000040000,
+      0x0000020000000000, 0x0000020000000000, 0x0000020000040000, 0x0000020000040000,
+      0x0000000000000004, 0x0000000000000004, 0x0000000000040004, 0x0000000000040004,
+      0x0000020000000004, 0x0000020000000004, 0x0000020000040004, 0x0000020000040004, ),
+    ( 0x0000000000000000, 0x0000400000000000, 0x0200000000000000, 0x0200400000000000,
+      0x0080000000000000, 0x0080400000000000, 0x0280000000000000, 0x0280400000000000,
+      0x0000008000000000, 0x0000408000000000, 0x0200008000000000, 0x0200408000000000,
+      0x0080008000000000, 0x0080408000000000, 0x0280008000000000, 0x0280408000000000, ),
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000000010000000, 0x0000000010000000,
+      0x0000000000001000, 0x0000000000001000, 0x0000000010001000, 0x0000000010001000,
+      0x0000000040000000, 0x0000000040000000, 0x0000000050000000, 0x0000000050000000,
+      0x0000000040001000, 0x0000000040001000, 0x0000000050001000, 0x0000000050001000, ),
+    ( 0x0000000000000000, 0x0000001000000000, 0x0000080000000000, 0x0000081000000000,
+      0x1000000000000000, 0x1000001000000000, 0x1000080000000000, 0x1000081000000000,
+      0x0004000000000000, 0x0004001000000000, 0x0004080000000000, 0x0004081000000000,
+      0x1004000000000000, 0x1004001000000000, 0x1004080000000000, 0x1004081000000000, ),
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000000000000080, 0x0000000000000080,
+      0x0000000000080000, 0x0000000000080000, 0x0000000000080080, 0x0000000000080080,
+      0x0000000000800000, 0x0000000000800000, 0x0000000000800080, 0x0000000000800080,
+      0x0000000000880000, 0x0000000000880000, 0x0000000000880080, 0x0000000000880080, ),
+    ( 0x0000000000000000, 0x0000000008000000, 0x0000002000000000, 0x0000002008000000,
+      0x0000100000000000, 0x0000100008000000, 0x0000102000000000, 0x0000102008000000,
+      0x0000200000000000, 0x0000200008000000, 0x0000202000000000, 0x0000202008000000,
+      0x0000300000000000, 0x0000300008000000, 0x0000302000000000, 0x0000302008000000, ),
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000000000400000, 0x0000000000400000,
+      0x0000000004000000, 0x0000000004000000, 0x0000000004400000, 0x0000000004400000,
+      0x0000000000000800, 0x0000000000000800, 0x0000000000400800, 0x0000000000400800,
+      0x0000000004000800, 0x0000000004000800, 0x0000000004400800, 0x0000000004400800, ),
+    ( 0x0000000000000000, 0x0000000000008000, 0x0040000000000000, 0x0040000000008000,
+      0x0000004000000000, 0x0000004000008000, 0x0040004000000000, 0x0040004000008000,
+      0x8000000000000000, 0x8000000000008000, 0x8040000000000000, 0x8040000000008000,
+      0x8000004000000000, 0x8000004000008000, 0x8040004000000000, 0x8040004000008000, ),
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000000000004000, 0x0000000000004000,
+      0x0000000000000008, 0x0000000000000008, 0x0000000000004008, 0x0000000000004008,
+      0x0000000000000010, 0x0000000000000010, 0x0000000000004010, 0x0000000000004010,
+      0x0000000000000018, 0x0000000000000018, 0x0000000000004018, 0x0000000000004018, ),
+    ( 0x0000000000000000, 0x0000000200000000, 0x0001000000000000, 0x0001000200000000,
+      0x0400000000000000, 0x0400000200000000, 0x0401000000000000, 0x0401000200000000,
+      0x0020000000000000, 0x0020000200000000, 0x0021000000000000, 0x0021000200000000,
+      0x0420000000000000, 0x0420000200000000, 0x0421000000000000, 0x0421000200000000, ),
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000010000000000, 0x0000010000000000,
+      0x0000000100000000, 0x0000000100000000, 0x0000010100000000, 0x0000010100000000,
+      0x0000000000100000, 0x0000000000100000, 0x0000010000100000, 0x0000010000100000,
+      0x0000000100100000, 0x0000000100100000, 0x0000010100100000, 0x0000010100100000, ),
+    ( 0x0000000000000000, 0x0000000080000000, 0x0000040000000000, 0x0000040080000000,
+      0x0010000000000000, 0x0010000080000000, 0x0010040000000000, 0x0010040080000000,
+      0x0000000800000000, 0x0000000880000000, 0x0000040800000000, 0x0000040880000000,
+      0x0010000800000000, 0x0010000880000000, 0x0010040800000000, 0x0010040880000000, ),
+        )
+    #---------------------------------------------------
+    # Subsequent key schedule rotation permutations
+    # PC2ROT - PC2 inverse, then Rotate, then PC2
+    #---------------------------------------------------
+    #NOTE: this was reordered from original table to make perm3264 logic simpler
+    PC2ROTA=(
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000000000000000, 0x0000000000000000,
+      0x0000000000200000, 0x0000000000200000, 0x0000000000200000, 0x0000000000200000,
+      0x0000000004000000, 0x0000000004000000, 0x0000000004000000, 0x0000000004000000,
+      0x0000000004200000, 0x0000000004200000, 0x0000000004200000, 0x0000000004200000, ),
+    ( 0x0000000000000000, 0x0000000000000800, 0x0000010000000000, 0x0000010000000800,
+      0x0000000000002000, 0x0000000000002800, 0x0000010000002000, 0x0000010000002800,
+      0x0000000010000000, 0x0000000010000800, 0x0000010010000000, 0x0000010010000800,
+      0x0000000010002000, 0x0000000010002800, 0x0000010010002000, 0x0000010010002800, ),
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000000000000000, 0x0000000000000000,
+      0x0000000100000000, 0x0000000100000000, 0x0000000100000000, 0x0000000100000000,
+      0x0000000000800000, 0x0000000000800000, 0x0000000000800000, 0x0000000000800000,
+      0x0000000100800000, 0x0000000100800000, 0x0000000100800000, 0x0000000100800000, ),
+    ( 0x0000000000000000, 0x0000020000000000, 0x0000000080000000, 0x0000020080000000,
+      0x0000000000400000, 0x0000020000400000, 0x0000000080400000, 0x0000020080400000,
+      0x0000000008000000, 0x0000020008000000, 0x0000000088000000, 0x0000020088000000,
+      0x0000000008400000, 0x0000020008400000, 0x0000000088400000, 0x0000020088400000, ),
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000000000000000, 0x0000000000000000,
+      0x0000000000000040, 0x0000000000000040, 0x0000000000000040, 0x0000000000000040,
+      0x0000000000001000, 0x0000000000001000, 0x0000000000001000, 0x0000000000001000,
+      0x0000000000001040, 0x0000000000001040, 0x0000000000001040, 0x0000000000001040, ),
+    ( 0x0000000000000000, 0x0000000000000010, 0x0000000000000400, 0x0000000000000410,
+      0x0000000000000080, 0x0000000000000090, 0x0000000000000480, 0x0000000000000490,
+      0x0000000040000000, 0x0000000040000010, 0x0000000040000400, 0x0000000040000410,
+      0x0000000040000080, 0x0000000040000090, 0x0000000040000480, 0x0000000040000490, ),
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000000000000000, 0x0000000000000000,
+      0x0000000000080000, 0x0000000000080000, 0x0000000000080000, 0x0000000000080000,
+      0x0000000000100000, 0x0000000000100000, 0x0000000000100000, 0x0000000000100000,
+      0x0000000000180000, 0x0000000000180000, 0x0000000000180000, 0x0000000000180000, ),
+    ( 0x0000000000000000, 0x0000000000040000, 0x0000000000000020, 0x0000000000040020,
+      0x0000000000000004, 0x0000000000040004, 0x0000000000000024, 0x0000000000040024,
+      0x0000000200000000, 0x0000000200040000, 0x0000000200000020, 0x0000000200040020,
+      0x0000000200000004, 0x0000000200040004, 0x0000000200000024, 0x0000000200040024, ),
+    ( 0x0000000000000000, 0x0000000000000008, 0x0000000000008000, 0x0000000000008008,
+      0x0010000000000000, 0x0010000000000008, 0x0010000000008000, 0x0010000000008008,
+      0x0020000000000000, 0x0020000000000008, 0x0020000000008000, 0x0020000000008008,
+      0x0030000000000000, 0x0030000000000008, 0x0030000000008000, 0x0030000000008008, ),
+    ( 0x0000000000000000, 0x0000400000000000, 0x0000080000000000, 0x0000480000000000,
+      0x0000100000000000, 0x0000500000000000, 0x0000180000000000, 0x0000580000000000,
+      0x4000000000000000, 0x4000400000000000, 0x4000080000000000, 0x4000480000000000,
+      0x4000100000000000, 0x4000500000000000, 0x4000180000000000, 0x4000580000000000, ),
+    ( 0x0000000000000000, 0x0000000000004000, 0x0000000020000000, 0x0000000020004000,
+      0x0001000000000000, 0x0001000000004000, 0x0001000020000000, 0x0001000020004000,
+      0x0200000000000000, 0x0200000000004000, 0x0200000020000000, 0x0200000020004000,
+      0x0201000000000000, 0x0201000000004000, 0x0201000020000000, 0x0201000020004000, ),
+    ( 0x0000000000000000, 0x1000000000000000, 0x0004000000000000, 0x1004000000000000,
+      0x0002000000000000, 0x1002000000000000, 0x0006000000000000, 0x1006000000000000,
+      0x0000000800000000, 0x1000000800000000, 0x0004000800000000, 0x1004000800000000,
+      0x0002000800000000, 0x1002000800000000, 0x0006000800000000, 0x1006000800000000, ),
+    ( 0x0000000000000000, 0x0040000000000000, 0x2000000000000000, 0x2040000000000000,
+      0x0000008000000000, 0x0040008000000000, 0x2000008000000000, 0x2040008000000000,
+      0x0000001000000000, 0x0040001000000000, 0x2000001000000000, 0x2040001000000000,
+      0x0000009000000000, 0x0040009000000000, 0x2000009000000000, 0x2040009000000000, ),
+    ( 0x0000000000000000, 0x0400000000000000, 0x8000000000000000, 0x8400000000000000,
+      0x0000002000000000, 0x0400002000000000, 0x8000002000000000, 0x8400002000000000,
+      0x0100000000000000, 0x0500000000000000, 0x8100000000000000, 0x8500000000000000,
+      0x0100002000000000, 0x0500002000000000, 0x8100002000000000, 0x8500002000000000, ),
+    ( 0x0000000000000000, 0x0000800000000000, 0x0800000000000000, 0x0800800000000000,
+      0x0000004000000000, 0x0000804000000000, 0x0800004000000000, 0x0800804000000000,
+      0x0000000400000000, 0x0000800400000000, 0x0800000400000000, 0x0800800400000000,
+      0x0000004400000000, 0x0000804400000000, 0x0800004400000000, 0x0800804400000000, ),
+    ( 0x0000000000000000, 0x0080000000000000, 0x0000040000000000, 0x0080040000000000,
+      0x0008000000000000, 0x0088000000000000, 0x0008040000000000, 0x0088040000000000,
+      0x0000200000000000, 0x0080200000000000, 0x0000240000000000, 0x0080240000000000,
+      0x0008200000000000, 0x0088200000000000, 0x0008240000000000, 0x0088240000000000, ),
+        )
+
+    #NOTE: this was reordered from original table to make perm3264 logic simpler
+    PC2ROTB=(
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000000000000000, 0x0000000000000000,
+      0x0000000000000400, 0x0000000000000400, 0x0000000000000400, 0x0000000000000400,
+      0x0000000000080000, 0x0000000000080000, 0x0000000000080000, 0x0000000000080000,
+      0x0000000000080400, 0x0000000000080400, 0x0000000000080400, 0x0000000000080400, ),
+    ( 0x0000000000000000, 0x0000000000800000, 0x0000000000004000, 0x0000000000804000,
+      0x0000000080000000, 0x0000000080800000, 0x0000000080004000, 0x0000000080804000,
+      0x0000000000040000, 0x0000000000840000, 0x0000000000044000, 0x0000000000844000,
+      0x0000000080040000, 0x0000000080840000, 0x0000000080044000, 0x0000000080844000, ),
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000000000000000, 0x0000000000000000,
+      0x0000000000000008, 0x0000000000000008, 0x0000000000000008, 0x0000000000000008,
+      0x0000000040000000, 0x0000000040000000, 0x0000000040000000, 0x0000000040000000,
+      0x0000000040000008, 0x0000000040000008, 0x0000000040000008, 0x0000000040000008, ),
+    ( 0x0000000000000000, 0x0000000020000000, 0x0000000200000000, 0x0000000220000000,
+      0x0000000000000080, 0x0000000020000080, 0x0000000200000080, 0x0000000220000080,
+      0x0000000000100000, 0x0000000020100000, 0x0000000200100000, 0x0000000220100000,
+      0x0000000000100080, 0x0000000020100080, 0x0000000200100080, 0x0000000220100080, ),
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000000000000000, 0x0000000000000000,
+      0x0000000000002000, 0x0000000000002000, 0x0000000000002000, 0x0000000000002000,
+      0x0000020000000000, 0x0000020000000000, 0x0000020000000000, 0x0000020000000000,
+      0x0000020000002000, 0x0000020000002000, 0x0000020000002000, 0x0000020000002000, ),
+    ( 0x0000000000000000, 0x0000000000000800, 0x0000000100000000, 0x0000000100000800,
+      0x0000000010000000, 0x0000000010000800, 0x0000000110000000, 0x0000000110000800,
+      0x0000000000000004, 0x0000000000000804, 0x0000000100000004, 0x0000000100000804,
+      0x0000000010000004, 0x0000000010000804, 0x0000000110000004, 0x0000000110000804, ),
+    ( 0x0000000000000000, 0x0000000000000000, 0x0000000000000000, 0x0000000000000000,
+      0x0000000000001000, 0x0000000000001000, 0x0000000000001000, 0x0000000000001000,
+      0x0000000000000010, 0x0000000000000010, 0x0000000000000010, 0x0000000000000010,
+      0x0000000000001010, 0x0000000000001010, 0x0000000000001010, 0x0000000000001010, ),
+    ( 0x0000000000000000, 0x0000000000000040, 0x0000010000000000, 0x0000010000000040,
+      0x0000000000200000, 0x0000000000200040, 0x0000010000200000, 0x0000010000200040,
+      0x0000000000008000, 0x0000000000008040, 0x0000010000008000, 0x0000010000008040,
+      0x0000000000208000, 0x0000000000208040, 0x0000010000208000, 0x0000010000208040, ),
+    ( 0x0000000000000000, 0x0000000004000000, 0x0000000008000000, 0x000000000c000000,
+      0x0400000000000000, 0x0400000004000000, 0x0400000008000000, 0x040000000c000000,
+      0x8000000000000000, 0x8000000004000000, 0x8000000008000000, 0x800000000c000000,
+      0x8400000000000000, 0x8400000004000000, 0x8400000008000000, 0x840000000c000000, ),
+    ( 0x0000000000000000, 0x0002000000000000, 0x0200000000000000, 0x0202000000000000,
+      0x1000000000000000, 0x1002000000000000, 0x1200000000000000, 0x1202000000000000,
+      0x0008000000000000, 0x000a000000000000, 0x0208000000000000, 0x020a000000000000,
+      0x1008000000000000, 0x100a000000000000, 0x1208000000000000, 0x120a000000000000, ),
+    ( 0x0000000000000000, 0x0000000000400000, 0x0000000000000020, 0x0000000000400020,
+      0x0040000000000000, 0x0040000000400000, 0x0040000000000020, 0x0040000000400020,
+      0x0800000000000000, 0x0800000000400000, 0x0800000000000020, 0x0800000000400020,
+      0x0840000000000000, 0x0840000000400000, 0x0840000000000020, 0x0840000000400020, ),
+    ( 0x0000000000000000, 0x0080000000000000, 0x0000008000000000, 0x0080008000000000,
+      0x2000000000000000, 0x2080000000000000, 0x2000008000000000, 0x2080008000000000,
+      0x0020000000000000, 0x00a0000000000000, 0x0020008000000000, 0x00a0008000000000,
+      0x2020000000000000, 0x20a0000000000000, 0x2020008000000000, 0x20a0008000000000, ),
+    ( 0x0000000000000000, 0x0000002000000000, 0x0000040000000000, 0x0000042000000000,
+      0x4000000000000000, 0x4000002000000000, 0x4000040000000000, 0x4000042000000000,
+      0x0000400000000000, 0x0000402000000000, 0x0000440000000000, 0x0000442000000000,
+      0x4000400000000000, 0x4000402000000000, 0x4000440000000000, 0x4000442000000000, ),
+    ( 0x0000000000000000, 0x0000004000000000, 0x0000200000000000, 0x0000204000000000,
+      0x0000080000000000, 0x0000084000000000, 0x0000280000000000, 0x0000284000000000,
+      0x0000800000000000, 0x0000804000000000, 0x0000a00000000000, 0x0000a04000000000,
+      0x0000880000000000, 0x0000884000000000, 0x0000a80000000000, 0x0000a84000000000, ),
+    ( 0x0000000000000000, 0x0000000800000000, 0x0000000400000000, 0x0000000c00000000,
+      0x0000100000000000, 0x0000100800000000, 0x0000100400000000, 0x0000100c00000000,
+      0x0010000000000000, 0x0010000800000000, 0x0010000400000000, 0x0010000c00000000,
+      0x0010100000000000, 0x0010100800000000, 0x0010100400000000, 0x0010100c00000000, ),
+    ( 0x0000000000000000, 0x0100000000000000, 0x0001000000000000, 0x0101000000000000,
+      0x0000001000000000, 0x0100001000000000, 0x0001001000000000, 0x0101001000000000,
+      0x0004000000000000, 0x0104000000000000, 0x0005000000000000, 0x0105000000000000,
+      0x0004001000000000, 0x0104001000000000, 0x0005001000000000, 0x0105001000000000, ),
+        )
+    #---------------------------------------------------
+    #PCXROT - PC1ROT, PC2ROTA, PC2ROTB listed in order
+    # of the PC1 rotation schedule, as used by des_setkey
+    #---------------------------------------------------
+    ##ROTATES = (1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1)
+    ##PCXROT = (
+    ##        PC1ROT,  PC2ROTA, PC2ROTB, PC2ROTB,
+    ##        PC2ROTB, PC2ROTB, PC2ROTB, PC2ROTB,
+    ##        PC2ROTA, PC2ROTB, PC2ROTB, PC2ROTB,
+    ##        PC2ROTB, PC2ROTB, PC2ROTB, PC2ROTA,
+    ##        )
+
+    #NOTE: modified PCXROT to contain entrys broken into pairs,
+    # to help generate them in format best used by encoder.
+    PCXROT = (
+            (PC1ROT,  PC2ROTA), (PC2ROTB, PC2ROTB),
+            (PC2ROTB, PC2ROTB), (PC2ROTB, PC2ROTB),
+            (PC2ROTA, PC2ROTB), (PC2ROTB, PC2ROTB),
+            (PC2ROTB, PC2ROTB), (PC2ROTB, PC2ROTA),
+            )
+
+    #---------------------------------------------------
+    # Bit reverse, intial permupation, expantion
+    # Initial permutation/expansion table
+    #---------------------------------------------------
+    #NOTE: this was reordered from original table to make perm3264 logic simpler
+    IE3264=(
+    ( 0x0000000000000000, 0x0000000000800800, 0x0000000000008008, 0x0000000000808808,
+      0x0000008008000000, 0x0000008008800800, 0x0000008008008008, 0x0000008008808808,
+      0x0000000080080000, 0x0000000080880800, 0x0000000080088008, 0x0000000080888808,
+      0x0000008088080000, 0x0000008088880800, 0x0000008088088008, 0x0000008088888808, ),
+    ( 0x0000000000000000, 0x0080080000000000, 0x0000800800000000, 0x0080880800000000,
+      0x0800000000000080, 0x0880080000000080, 0x0800800800000080, 0x0880880800000080,
+      0x8008000000000000, 0x8088080000000000, 0x8008800800000000, 0x8088880800000000,
+      0x8808000000000080, 0x8888080000000080, 0x8808800800000080, 0x8888880800000080, ),
+    ( 0x0000000000000000, 0x0000000000001000, 0x0000000000000010, 0x0000000000001010,
+      0x0000000010000000, 0x0000000010001000, 0x0000000010000010, 0x0000000010001010,
+      0x0000000000100000, 0x0000000000101000, 0x0000000000100010, 0x0000000000101010,
+      0x0000000010100000, 0x0000000010101000, 0x0000000010100010, 0x0000000010101010, ),
+    ( 0x0000000000000000, 0x0000100000000000, 0x0000001000000000, 0x0000101000000000,
+      0x1000000000000000, 0x1000100000000000, 0x1000001000000000, 0x1000101000000000,
+      0x0010000000000000, 0x0010100000000000, 0x0010001000000000, 0x0010101000000000,
+      0x1010000000000000, 0x1010100000000000, 0x1010001000000000, 0x1010101000000000, ),
+    ( 0x0000000000000000, 0x0000000000002000, 0x0000000000000020, 0x0000000000002020,
+      0x0000000020000000, 0x0000000020002000, 0x0000000020000020, 0x0000000020002020,
+      0x0000000000200000, 0x0000000000202000, 0x0000000000200020, 0x0000000000202020,
+      0x0000000020200000, 0x0000000020202000, 0x0000000020200020, 0x0000000020202020, ),
+    ( 0x0000000000000000, 0x0000200000000000, 0x0000002000000000, 0x0000202000000000,
+      0x2000000000000000, 0x2000200000000000, 0x2000002000000000, 0x2000202000000000,
+      0x0020000000000000, 0x0020200000000000, 0x0020002000000000, 0x0020202000000000,
+      0x2020000000000000, 0x2020200000000000, 0x2020002000000000, 0x2020202000000000, ),
+    ( 0x0000000000000000, 0x0000000000004004, 0x0400000000000040, 0x0400000000004044,
+      0x0000000040040000, 0x0000000040044004, 0x0400000040040040, 0x0400000040044044,
+      0x0000000000400400, 0x0000000000404404, 0x0400000000400440, 0x0400000000404444,
+      0x0000000040440400, 0x0000000040444404, 0x0400000040440440, 0x0400000040444444, ),
+    ( 0x0000000000000000, 0x0000400400000000, 0x0000004004000000, 0x0000404404000000,
+      0x4004000000000000, 0x4004400400000000, 0x4004004004000000, 0x4004404404000000,
+      0x0040040000000000, 0x0040440400000000, 0x0040044004000000, 0x0040444404000000,
+      0x4044040000000000, 0x4044440400000000, 0x4044044004000000, 0x4044444404000000, ),
+        )
+
+    #---------------------------------------------------
+    # Table that combines the S, P, and E operations.
+    #---------------------------------------------------
+    SPE=(
+    ( 0x0080088008200000, 0x0000008008000000, 0x0000000000200020, 0x0080088008200020,
+      0x0000000000200000, 0x0080088008000020, 0x0000008008000020, 0x0000000000200020,
+      0x0080088008000020, 0x0080088008200000, 0x0000008008200000, 0x0080080000000020,
+      0x0080080000200020, 0x0000000000200000, 0x0000000000000000, 0x0000008008000020,
+      0x0000008008000000, 0x0000000000000020, 0x0080080000200000, 0x0080088008000000,
+      0x0080088008200020, 0x0000008008200000, 0x0080080000000020, 0x0080080000200000,
+      0x0000000000000020, 0x0080080000000000, 0x0080088008000000, 0x0000008008200020,
+      0x0080080000000000, 0x0080080000200020, 0x0000008008200020, 0x0000000000000000,
+      0x0000000000000000, 0x0080088008200020, 0x0080080000200000, 0x0000008008000020,
+      0x0080088008200000, 0x0000008008000000, 0x0080080000000020, 0x0080080000200000,
+      0x0000008008200020, 0x0080080000000000, 0x0080088008000000, 0x0000000000200020,
+      0x0080088008000020, 0x0000000000000020, 0x0000000000200020, 0x0000008008200000,
+      0x0080088008200020, 0x0080088008000000, 0x0000008008200000, 0x0080080000200020,
+      0x0000000000200000, 0x0080080000000020, 0x0000008008000020, 0x0000000000000000,
+      0x0000008008000000, 0x0000000000200000, 0x0080080000200020, 0x0080088008200000,
+      0x0000000000000020, 0x0000008008200020, 0x0080080000000000, 0x0080088008000020, ),
+    ( 0x1000800810004004, 0x0000000000000000, 0x0000800810000000, 0x0000000010004004,
+      0x1000000000004004, 0x1000800800000000, 0x0000800800004004, 0x0000800810000000,
+      0x0000800800000000, 0x1000000010004004, 0x1000000000000000, 0x0000800800004004,
+      0x1000000010000000, 0x0000800810004004, 0x0000000010004004, 0x1000000000000000,
+      0x0000000010000000, 0x1000800800004004, 0x1000000010004004, 0x0000800800000000,
+      0x1000800810000000, 0x0000000000004004, 0x0000000000000000, 0x1000000010000000,
+      0x1000800800004004, 0x1000800810000000, 0x0000800810004004, 0x1000000000004004,
+      0x0000000000004004, 0x0000000010000000, 0x1000800800000000, 0x1000800810004004,
+      0x1000000010000000, 0x0000800810004004, 0x0000800800004004, 0x1000800810000000,
+      0x1000800810004004, 0x1000000010000000, 0x1000000000004004, 0x0000000000000000,
+      0x0000000000004004, 0x1000800800000000, 0x0000000010000000, 0x1000000010004004,
+      0x0000800800000000, 0x0000000000004004, 0x1000800810000000, 0x1000800800004004,
+      0x0000800810004004, 0x0000800800000000, 0x0000000000000000, 0x1000000000004004,
+      0x1000000000000000, 0x1000800810004004, 0x0000800810000000, 0x0000000010004004,
+      0x1000000010004004, 0x0000000010000000, 0x1000800800000000, 0x0000800800004004,
+      0x1000800800004004, 0x1000000000000000, 0x0000000010004004, 0x0000800810000000, ),
+    ( 0x0000000000400410, 0x0010004004400400, 0x0010000000000000, 0x0010000000400410,
+      0x0000004004000010, 0x0000000000400400, 0x0010000000400410, 0x0010004004000000,
+      0x0010000000400400, 0x0000004004000000, 0x0000004004400400, 0x0000000000000010,
+      0x0010004004400410, 0x0010000000000010, 0x0000000000000010, 0x0000004004400410,
+      0x0000000000000000, 0x0000004004000010, 0x0010004004400400, 0x0010000000000000,
+      0x0010000000000010, 0x0010004004400410, 0x0000004004000000, 0x0000000000400410,
+      0x0000004004400410, 0x0010000000400400, 0x0010004004000010, 0x0000004004400400,
+      0x0010004004000000, 0x0000000000000000, 0x0000000000400400, 0x0010004004000010,
+      0x0010004004400400, 0x0010000000000000, 0x0000000000000010, 0x0000004004000000,
+      0x0010000000000010, 0x0000004004000010, 0x0000004004400400, 0x0010000000400410,
+      0x0000000000000000, 0x0010004004400400, 0x0010004004000000, 0x0000004004400410,
+      0x0000004004000010, 0x0000000000400400, 0x0010004004400410, 0x0000000000000010,
+      0x0010004004000010, 0x0000000000400410, 0x0000000000400400, 0x0010004004400410,
+      0x0000004004000000, 0x0010000000400400, 0x0010000000400410, 0x0010004004000000,
+      0x0010000000400400, 0x0000000000000000, 0x0000004004400410, 0x0010000000000010,
+      0x0000000000400410, 0x0010004004000010, 0x0010000000000000, 0x0000004004400400, ),
+    ( 0x0800100040040080, 0x0000100000001000, 0x0800000000000080, 0x0800100040041080,
+      0x0000000000000000, 0x0000000040041000, 0x0800100000001080, 0x0800000040040080,
+      0x0000100040041000, 0x0800000000001080, 0x0000000000001000, 0x0800100000000080,
+      0x0800000000001080, 0x0800100040040080, 0x0000000040040000, 0x0000000000001000,
+      0x0800000040041080, 0x0000100040040000, 0x0000100000000000, 0x0800000000000080,
+      0x0000100040040000, 0x0800100000001080, 0x0000000040041000, 0x0000100000000000,
+      0x0800100000000080, 0x0000000000000000, 0x0800000040040080, 0x0000100040041000,
+      0x0000100000001000, 0x0800000040041080, 0x0800100040041080, 0x0000000040040000,
+      0x0800000040041080, 0x0800100000000080, 0x0000000040040000, 0x0800000000001080,
+      0x0000100040040000, 0x0000100000001000, 0x0800000000000080, 0x0000000040041000,
+      0x0800100000001080, 0x0000000000000000, 0x0000100000000000, 0x0800000040040080,
+      0x0000000000000000, 0x0800000040041080, 0x0000100040041000, 0x0000100000000000,
+      0x0000000000001000, 0x0800100040041080, 0x0800100040040080, 0x0000000040040000,
+      0x0800100040041080, 0x0800000000000080, 0x0000100000001000, 0x0800100040040080,
+      0x0800000040040080, 0x0000100040040000, 0x0000000040041000, 0x0800100000001080,
+      0x0800100000000080, 0x0000000000001000, 0x0800000000001080, 0x0000100040041000, ),
+    ( 0x0000000000800800, 0x0000001000000000, 0x0040040000000000, 0x2040041000800800,
+      0x2000001000800800, 0x0040040000800800, 0x2040041000000000, 0x0000001000800800,
+      0x0000001000000000, 0x2000000000000000, 0x2000000000800800, 0x0040041000000000,
+      0x2040040000800800, 0x2000001000800800, 0x0040041000800800, 0x0000000000000000,
+      0x0040041000000000, 0x0000000000800800, 0x2000001000000000, 0x2040040000000000,
+      0x0040040000800800, 0x2040041000000000, 0x0000000000000000, 0x2000000000800800,
+      0x2000000000000000, 0x2040040000800800, 0x2040041000800800, 0x2000001000000000,
+      0x0000001000800800, 0x0040040000000000, 0x2040040000000000, 0x0040041000800800,
+      0x0040041000800800, 0x2040040000800800, 0x2000001000000000, 0x0000001000800800,
+      0x0000001000000000, 0x2000000000000000, 0x2000000000800800, 0x0040040000800800,
+      0x0000000000800800, 0x0040041000000000, 0x2040041000800800, 0x0000000000000000,
+      0x2040041000000000, 0x0000000000800800, 0x0040040000000000, 0x2000001000000000,
+      0x2040040000800800, 0x0040040000000000, 0x0000000000000000, 0x2040041000800800,
+      0x2000001000800800, 0x0040041000800800, 0x2040040000000000, 0x0000001000000000,
+      0x0040041000000000, 0x2000001000800800, 0x0040040000800800, 0x2040040000000000,
+      0x2000000000000000, 0x2040041000000000, 0x0000001000800800, 0x2000000000800800, ),
+    ( 0x4004000000008008, 0x4004000020000000, 0x0000000000000000, 0x0000200020008008,
+      0x4004000020000000, 0x0000200000000000, 0x4004200000008008, 0x0000000020000000,
+      0x4004200000000000, 0x4004200020008008, 0x0000200020000000, 0x0000000000008008,
+      0x0000200000008008, 0x4004000000008008, 0x0000000020008008, 0x4004200020000000,
+      0x0000000020000000, 0x4004200000008008, 0x4004000020008008, 0x0000000000000000,
+      0x0000200000000000, 0x4004000000000000, 0x0000200020008008, 0x4004000020008008,
+      0x4004200020008008, 0x0000000020008008, 0x0000000000008008, 0x4004200000000000,
+      0x4004000000000000, 0x0000200020000000, 0x4004200020000000, 0x0000200000008008,
+      0x4004200000000000, 0x0000000000008008, 0x0000200000008008, 0x4004200020000000,
+      0x0000200020008008, 0x4004000020000000, 0x0000000000000000, 0x0000200000008008,
+      0x0000000000008008, 0x0000200000000000, 0x4004000020008008, 0x0000000020000000,
+      0x4004000020000000, 0x4004200020008008, 0x0000200020000000, 0x4004000000000000,
+      0x4004200020008008, 0x0000200020000000, 0x0000000020000000, 0x4004200000008008,
+      0x4004000000008008, 0x0000000020008008, 0x4004200020000000, 0x0000000000000000,
+      0x0000200000000000, 0x4004000000008008, 0x4004200000008008, 0x0000200020008008,
+      0x0000000020008008, 0x4004200000000000, 0x4004000000000000, 0x4004000020008008, ),
+    ( 0x0000400400000000, 0x0020000000000000, 0x0020000000100000, 0x0400000000100040,
+      0x0420400400100040, 0x0400400400000040, 0x0020400400000000, 0x0000000000000000,
+      0x0000000000100000, 0x0420000000100040, 0x0420000000000040, 0x0000400400100000,
+      0x0400000000000040, 0x0020400400100000, 0x0000400400100000, 0x0420000000000040,
+      0x0420000000100040, 0x0000400400000000, 0x0400400400000040, 0x0420400400100040,
+      0x0000000000000000, 0x0020000000100000, 0x0400000000100040, 0x0020400400000000,
+      0x0400400400100040, 0x0420400400000040, 0x0020400400100000, 0x0400000000000040,
+      0x0420400400000040, 0x0400400400100040, 0x0020000000000000, 0x0000000000100000,
+      0x0420400400000040, 0x0000400400100000, 0x0400400400100040, 0x0420000000000040,
+      0x0000400400000000, 0x0020000000000000, 0x0000000000100000, 0x0400400400100040,
+      0x0420000000100040, 0x0420400400000040, 0x0020400400000000, 0x0000000000000000,
+      0x0020000000000000, 0x0400000000100040, 0x0400000000000040, 0x0020000000100000,
+      0x0000000000000000, 0x0420000000100040, 0x0020000000100000, 0x0020400400000000,
+      0x0420000000000040, 0x0000400400000000, 0x0420400400100040, 0x0000000000100000,
+      0x0020400400100000, 0x0400000000000040, 0x0400400400000040, 0x0420400400100040,
+      0x0400000000100040, 0x0020400400100000, 0x0000400400100000, 0x0400400400000040, ),
+    ( 0x8008000080082000, 0x0000002080082000, 0x8008002000000000, 0x0000000000000000,
+      0x0000002000002000, 0x8008000080080000, 0x0000000080082000, 0x8008002080082000,
+      0x8008000000000000, 0x0000000000002000, 0x0000002080080000, 0x8008002000000000,
+      0x8008002080080000, 0x8008002000002000, 0x8008000000002000, 0x0000000080082000,
+      0x0000002000000000, 0x8008002080080000, 0x8008000080080000, 0x0000002000002000,
+      0x8008002080082000, 0x8008000000002000, 0x0000000000000000, 0x0000002080080000,
+      0x0000000000002000, 0x0000000080080000, 0x8008002000002000, 0x8008000080082000,
+      0x0000000080080000, 0x0000002000000000, 0x0000002080082000, 0x8008000000000000,
+      0x0000000080080000, 0x0000002000000000, 0x8008000000002000, 0x8008002080082000,
+      0x8008002000000000, 0x0000000000002000, 0x0000000000000000, 0x0000002080080000,
+      0x8008000080082000, 0x8008002000002000, 0x0000002000002000, 0x8008000080080000,
+      0x0000002080082000, 0x8008000000000000, 0x8008000080080000, 0x0000002000002000,
+      0x8008002080082000, 0x0000000080080000, 0x0000000080082000, 0x8008000000002000,
+      0x0000002080080000, 0x8008002000000000, 0x8008002000002000, 0x0000000080082000,
+      0x8008000000000000, 0x0000002080082000, 0x8008002080080000, 0x0000000000000000,
+      0x0000000000002000, 0x8008000080082000, 0x0000002000000000, 0x8008002080080000, ),
+        )
+
+    #---------------------------------------------------
+    # compressed/interleaved => final permutation table
+    # Compression, final permutation, bit reverse
+    #---------------------------------------------------
+    #NOTE: this was reordered from original table to make perm6464 logic simpler
+    CF6464=(
+    ( 0x0000000000000000, 0x0000002000000000, 0x0000200000000000, 0x0000202000000000,
+      0x0020000000000000, 0x0020002000000000, 0x0020200000000000, 0x0020202000000000,
+      0x2000000000000000, 0x2000002000000000, 0x2000200000000000, 0x2000202000000000,
+      0x2020000000000000, 0x2020002000000000, 0x2020200000000000, 0x2020202000000000, ),
+    ( 0x0000000000000000, 0x0000000200000000, 0x0000020000000000, 0x0000020200000000,
+      0x0002000000000000, 0x0002000200000000, 0x0002020000000000, 0x0002020200000000,
+      0x0200000000000000, 0x0200000200000000, 0x0200020000000000, 0x0200020200000000,
+      0x0202000000000000, 0x0202000200000000, 0x0202020000000000, 0x0202020200000000, ),
+    ( 0x0000000000000000, 0x0000000000000020, 0x0000000000002000, 0x0000000000002020,
+      0x0000000000200000, 0x0000000000200020, 0x0000000000202000, 0x0000000000202020,
+      0x0000000020000000, 0x0000000020000020, 0x0000000020002000, 0x0000000020002020,
+      0x0000000020200000, 0x0000000020200020, 0x0000000020202000, 0x0000000020202020, ),
+    ( 0x0000000000000000, 0x0000000000000002, 0x0000000000000200, 0x0000000000000202,
+      0x0000000000020000, 0x0000000000020002, 0x0000000000020200, 0x0000000000020202,
+      0x0000000002000000, 0x0000000002000002, 0x0000000002000200, 0x0000000002000202,
+      0x0000000002020000, 0x0000000002020002, 0x0000000002020200, 0x0000000002020202, ),
+    ( 0x0000000000000000, 0x0000008000000000, 0x0000800000000000, 0x0000808000000000,
+      0x0080000000000000, 0x0080008000000000, 0x0080800000000000, 0x0080808000000000,
+      0x8000000000000000, 0x8000008000000000, 0x8000800000000000, 0x8000808000000000,
+      0x8080000000000000, 0x8080008000000000, 0x8080800000000000, 0x8080808000000000, ),
+    ( 0x0000000000000000, 0x0000000800000000, 0x0000080000000000, 0x0000080800000000,
+      0x0008000000000000, 0x0008000800000000, 0x0008080000000000, 0x0008080800000000,
+      0x0800000000000000, 0x0800000800000000, 0x0800080000000000, 0x0800080800000000,
+      0x0808000000000000, 0x0808000800000000, 0x0808080000000000, 0x0808080800000000, ),
+    ( 0x0000000000000000, 0x0000000000000080, 0x0000000000008000, 0x0000000000008080,
+      0x0000000000800000, 0x0000000000800080, 0x0000000000808000, 0x0000000000808080,
+      0x0000000080000000, 0x0000000080000080, 0x0000000080008000, 0x0000000080008080,
+      0x0000000080800000, 0x0000000080800080, 0x0000000080808000, 0x0000000080808080, ),
+    ( 0x0000000000000000, 0x0000000000000008, 0x0000000000000800, 0x0000000000000808,
+      0x0000000000080000, 0x0000000000080008, 0x0000000000080800, 0x0000000000080808,
+      0x0000000008000000, 0x0000000008000008, 0x0000000008000800, 0x0000000008000808,
+      0x0000000008080000, 0x0000000008080008, 0x0000000008080800, 0x0000000008080808, ),
+    ( 0x0000000000000000, 0x0000001000000000, 0x0000100000000000, 0x0000101000000000,
+      0x0010000000000000, 0x0010001000000000, 0x0010100000000000, 0x0010101000000000,
+      0x1000000000000000, 0x1000001000000000, 0x1000100000000000, 0x1000101000000000,
+      0x1010000000000000, 0x1010001000000000, 0x1010100000000000, 0x1010101000000000, ),
+    ( 0x0000000000000000, 0x0000000100000000, 0x0000010000000000, 0x0000010100000000,
+      0x0001000000000000, 0x0001000100000000, 0x0001010000000000, 0x0001010100000000,
+      0x0100000000000000, 0x0100000100000000, 0x0100010000000000, 0x0100010100000000,
+      0x0101000000000000, 0x0101000100000000, 0x0101010000000000, 0x0101010100000000, ),
+    ( 0x0000000000000000, 0x0000000000000010, 0x0000000000001000, 0x0000000000001010,
+      0x0000000000100000, 0x0000000000100010, 0x0000000000101000, 0x0000000000101010,
+      0x0000000010000000, 0x0000000010000010, 0x0000000010001000, 0x0000000010001010,
+      0x0000000010100000, 0x0000000010100010, 0x0000000010101000, 0x0000000010101010, ),
+    ( 0x0000000000000000, 0x0000000000000001, 0x0000000000000100, 0x0000000000000101,
+      0x0000000000010000, 0x0000000000010001, 0x0000000000010100, 0x0000000000010101,
+      0x0000000001000000, 0x0000000001000001, 0x0000000001000100, 0x0000000001000101,
+      0x0000000001010000, 0x0000000001010001, 0x0000000001010100, 0x0000000001010101, ),
+    ( 0x0000000000000000, 0x0000004000000000, 0x0000400000000000, 0x0000404000000000,
+      0x0040000000000000, 0x0040004000000000, 0x0040400000000000, 0x0040404000000000,
+      0x4000000000000000, 0x4000004000000000, 0x4000400000000000, 0x4000404000000000,
+      0x4040000000000000, 0x4040004000000000, 0x4040400000000000, 0x4040404000000000, ),
+    ( 0x0000000000000000, 0x0000000400000000, 0x0000040000000000, 0x0000040400000000,
+      0x0004000000000000, 0x0004000400000000, 0x0004040000000000, 0x0004040400000000,
+      0x0400000000000000, 0x0400000400000000, 0x0400040000000000, 0x0400040400000000,
+      0x0404000000000000, 0x0404000400000000, 0x0404040000000000, 0x0404040400000000, ),
+    ( 0x0000000000000000, 0x0000000000000040, 0x0000000000004000, 0x0000000000004040,
+      0x0000000000400000, 0x0000000000400040, 0x0000000000404000, 0x0000000000404040,
+      0x0000000040000000, 0x0000000040000040, 0x0000000040004000, 0x0000000040004040,
+      0x0000000040400000, 0x0000000040400040, 0x0000000040404000, 0x0000000040404040, ),
+    ( 0x0000000000000000, 0x0000000000000004, 0x0000000000000400, 0x0000000000000404,
+      0x0000000000040000, 0x0000000000040004, 0x0000000000040400, 0x0000000000040404,
+      0x0000000004000000, 0x0000000004000004, 0x0000000004000400, 0x0000000004000404,
+      0x0000000004040000, 0x0000000004040004, 0x0000000004040400, 0x0000000004040404, ),
+    )
+    #=========================================================
+    #eof load_data
+    #=========================================================
+
+def permute(c, p):
+    """Returns the permutation of the given 32-bit or 64-bit code with
+    the specified permutation table."""
+    #NOTE: only difference between 32 & 64 bit permutations
+    #is that len(p)==8 for 32 bit, and len(p)==16 for 64 bit.
+    out = 0
+    for r in p:
+        out |= r[c&0xf]
+        c >>= 4
+    return out
+
+#=========================================================
+#des frontend
+#=========================================================
+def expand_des_key(source):
+    "convert 7 byte des key to 8 byte des key (by adding parity bit every 7 bits)"
+    #NOTE: could probably do this much more cleverly and efficiently,
+    # but no need really given it's use
+    assert len(source) == 7
+
+    def iter_bits(source):
+        for c in source:
+            v = ord(c)
+            for i in xrange(7,-1,-1):
+                yield (v>>i) & 1
+
+    out = 0
+    p = 1
+    for i, b in enumerate(iter_bits(source)):
+        out = (out<<1) + b
+        p ^= b
+        if i % 7 == 6:
+            out = (out<<1) + p
+            p = 1
+
+    return ''.join(
+        chr((out>>s) & 0xFF)
+        for s in xrange(8*7,-8,-8)
+    )
+
+def des_encrypt_block(key, input):
+    """do traditional encryption of a single DES block
+
+    :arg key: 8 byte des key string
+    :arg input: 8 byte plaintext string
+    :returns: 8 byte ciphertext string
+    """
+    assert len(input) == 8
+    if len(key) == 7:
+        key = expand_des_key(key)
+    assert len(key) == 8
+    input = bytes_to_int(input)
+    key = bytes_to_int(key)
+    out = mdes_encrypt_int_block(key, input, 0, 1)
+    return int_to_bytes(out, 8)
+
+def mdes_encrypt_int_block(key, input, salt=0, rounds=1):
+    """do modified multi-round DES encryption of single DES block.
+
+    the function implemented the salted, variable-round version
+    of DES used by des-crypt and ext-des-crypt.
+
+    it also can perform regular DES encryption
+    by setting salt=0 and rounds=1
+
+    :arg key: 8 byte des key as integer
+    :arg input: 8 byte plaintext block as integer
+    :arg salt: 12 or 24 bit salt as integer, used to mutate output
+    :arg rounds: number of rounds of DES encryption to apply.
+
+    :returns:
+        resulting block as 8 byte integer
+    """
+    global SPE, PCXROT, IE3264, CF6464
+
+    #bounds check
+    assert 0 <= input <= INT_64_MAX, "input value out of range"
+    assert 0 <= salt <= INT_24_MAX, "salt value out of range"
+    assert rounds >= 0, "rounds out of range"
+    assert 0 <= key <= INT_64_MAX, "key value out of range"
+
+    #load tables if not already done
+    if PCXROT is None:
+        load_tables()
+
+    #convert key int -> key schedule
+    #NOTE: generation was modified to output two elements at a time,
+    #to optimize for per-round algorithm below.
+    mask = ~0x0303030300000000
+    def _gen(K):
+        for p_even, p_odd in PCXROT:
+            K1 = permute(K, p_even)
+            K = permute(K1, p_odd)
+            yield K1 & mask, K & mask
+    ks_list = list(_gen(key))
+
+    #expand 24 bit salt -> 32 bit
+    salt = (
+        ((salt & 0x00003f) << 26) |
+        ((salt & 0x000fc0) << 12) |
+        ((salt & 0x03f000) >> 2) |
+        ((salt & 0xfc0000) >> 16)
+        )
+
+    #init L & R
+    if input == 0:
+        L = R = 0
+    else:
+        L = ((input >> 31) & 0xaaaaaaaa) | (input & 0x55555555)
+        L = permute(L, IE3264)
+
+        R = ((input >> 32) & 0xaaaaaaaa) | ((input >> 1) & 0x55555555)
+        R = permute(R, IE3264)
+
+    #load SPE into local vars to speed things up and remove an array access call
+    SPE0, SPE1, SPE2, SPE3, SPE4, SPE5, SPE6, SPE7 = SPE
+
+    #run specified number of passed
+    while rounds:
+        rounds -= 1
+
+        #run over each part of the schedule
+        for ks_even, ks_odd in ks_list:
+            k = ((R>>32) ^ R) & salt
+            B = (k<<32) ^ k ^ R ^ ks_even
+
+            L ^= (SPE0[(B>>58)&0x3f] ^ SPE1[(B>>50)&0x3f] ^
+                  SPE2[(B>>42)&0x3f] ^ SPE3[(B>>34)&0x3f] ^
+                  SPE4[(B>>26)&0x3f] ^ SPE5[(B>>18)&0x3f] ^
+                  SPE6[(B>>10)&0x3f] ^ SPE7[(B>>2)&0x3f])
+
+            k = ((L>>32) ^ L) & salt
+            B = (k<<32) ^ k ^ L ^ ks_odd
+
+            R ^= (SPE0[(B>>58)&0x3f] ^ SPE1[(B>>50)&0x3f] ^
+                  SPE2[(B>>42)&0x3f] ^ SPE3[(B>>34)&0x3f] ^
+                  SPE4[(B>>26)&0x3f] ^ SPE5[(B>>18)&0x3f] ^
+                  SPE6[(B>>10)&0x3f] ^ SPE7[(B>>2)&0x3f])
+
+        # swap L and R
+        L, R = R, L
+
+    C = (
+            ((L>>3) &  0x0f0f0f0f00000000L)
+            |
+            ((L<<33) & 0xf0f0f0f000000000L)
+            |
+            ((R>>35) & 0x000000000f0f0f0fL)
+            |
+            ((R<<1) &  0x00000000f0f0f0f0L)
+        )
+
+    C = permute(C, CF6464)
+
+    return C
+
+#=========================================================
+#eof
+#=========================================================