File Coverage

blib/lib/Crypt/DES_PP.pm

Criterion	Covered	Total	%
statement	181	184	98.3
branch	9	14	64.2
condition			n/a
subroutine	28	29	96.5
pod	0	6	0.0
total	218	233	93.5

# -*- perl -*-
# DES_PP.pm - Pure perl implementation of DES.
#
# The master file for the module is DES_PP.m4 which needs to be run through
# the m4.  Please edit DES_PP.m4 if you need to modify!

package Crypt::DES_PP;

use strict;
use Carp;
use integer;

use vars qw($VERSION @ISA @EXPORT @EXPORT_OK);

require Exporter;

@ISA = qw (Exporter);
@EXPORT = qw ();
@EXPORT_OK = qw ();
$VERSION = '1.00';

use constant BLKSIZE => 8;

# Stolen from Crypt::DES.
sub usage {
    my ($package, $filename, $line, $subr) = caller (1);
    $Carp::CarpLevel = 2;
    croak "Usage: $subr (@_)";
}

sub blocksize () { BLKSIZE };
sub keysize () { BLKSIZE };

sub expand_key ($);
sub crypt ($$$);

sub new {
    usage ("new Crypt::DES_PP key")
	unless @_ == 2;
    my ($package, $key) = @_;

    bless { ks => Crypt::DES_PP::expand_key ($key) }, $package;
}

sub encrypt {
    usage ("encrypt data[8 bytes]") unless @_ == 2;

    my ($self,$data) = @_;
    return Crypt::DES_PP::crypt ($data, $self->{ks}, 1);
}

sub decrypt {
    usage("decrypt data[8 bytes]") unless @_ == 2;

    my ($self,$data) = @_;
    return Crypt::DES_PP::crypt ($data, $self->{ks}, 0);
}

use constant ITERATIONS => 16;

# These used to be a single reference to an array of array references.
# Splitting them up into distinct constants slightly improves performance.
use constant des_SPtrans_0 =>
    [ # Nibble 0
      0x00820200, 0x00020000, 0x80800000, 0x80820200,
      0x00800000, 0x80020200, 0x80020000, 0x80800000,
      0x80020200, 0x00820200, 0x00820000, 0x80000200,
      0x80800200, 0x00800000, 0x00000000, 0x80020000,
      0x00020000, 0x80000000, 0x00800200, 0x00020200,
      0x80820200, 0x00820000, 0x80000200, 0x00800200,
      0x80000000, 0x00000200, 0x00020200, 0x80820000,
      0x00000200, 0x80800200, 0x80820000, 0x00000000,
      0x00000000, 0x80820200, 0x00800200, 0x80020000,
      0x00820200, 0x00020000, 0x80000200, 0x00800200,
      0x80820000, 0x00000200, 0x00020200, 0x80800000,
      0x80020200, 0x80000000, 0x80800000, 0x00820000,
      0x80820200, 0x00020200, 0x00820000, 0x80800200,
      0x00800000, 0x80000200, 0x80020000, 0x00000000,
      0x00020000, 0x00800000, 0x80800200, 0x00820200,
      0x80000000, 0x80820000, 0x00000200, 0x80020200,
      ];
use constant des_SPtrans_1 =>
    [ # Nibble 1
      0x10042004, 0x00000000, 0x00042000, 0x10040000,
      0x10000004, 0x00002004, 0x10002000, 0x00042000,
      0x00002000, 0x10040004, 0x00000004, 0x10002000,
      0x00040004, 0x10042000, 0x10040000, 0x00000004,
      0x00040000, 0x10002004, 0x10040004, 0x00002000,
      0x00042004, 0x10000000, 0x00000000, 0x00040004,
      0x10002004, 0x00042004, 0x10042000, 0x10000004,
      0x10000000, 0x00040000, 0x00002004, 0x10042004,
      0x00040004, 0x10042000, 0x10002000, 0x00042004,
      0x10042004, 0x00040004, 0x10000004, 0x00000000,
      0x10000000, 0x00002004, 0x00040000, 0x10040004,
      0x00002000, 0x10000000, 0x00042004, 0x10002004,
      0x10042000, 0x00002000, 0x00000000, 0x10000004,
      0x00000004, 0x10042004, 0x00042000, 0x10040000,
      0x10040004, 0x00040000, 0x00002004, 0x10002000,
      0x10002004, 0x00000004, 0x10040000, 0x00042000,
      ];
use constant des_SPtrans_2 =>
    [ # Nibble 2
      0x41000000, 0x01010040, 0x00000040, 0x41000040,
      0x40010000, 0x01000000, 0x41000040, 0x00010040,
      0x01000040, 0x00010000, 0x01010000, 0x40000000,
      0x41010040, 0x40000040, 0x40000000, 0x41010000,
      0x00000000, 0x40010000, 0x01010040, 0x00000040,
      0x40000040, 0x41010040, 0x00010000, 0x41000000,
      0x41010000, 0x01000040, 0x40010040, 0x01010000,
      0x00010040, 0x00000000, 0x01000000, 0x40010040,
      0x01010040, 0x00000040, 0x40000000, 0x00010000,
      0x40000040, 0x40010000, 0x01010000, 0x41000040,
      0x00000000, 0x01010040, 0x00010040, 0x41010000,
      0x40010000, 0x01000000, 0x41010040, 0x40000000,
      0x40010040, 0x41000000, 0x01000000, 0x41010040,
      0x00010000, 0x01000040, 0x41000040, 0x00010040,
      0x01000040, 0x00000000, 0x41010000, 0x40000040,
      0x41000000, 0x40010040, 0x00000040, 0x01010000,
      ];
use constant des_SPtrans_3 =>
    [ # Nibble 3
      0x00100402, 0x04000400, 0x00000002, 0x04100402,
      0x00000000, 0x04100000, 0x04000402, 0x00100002,
      0x04100400, 0x04000002, 0x04000000, 0x00000402,
      0x04000002, 0x00100402, 0x00100000, 0x04000000,
      0x04100002, 0x00100400, 0x00000400, 0x00000002,
      0x00100400, 0x04000402, 0x04100000, 0x00000400,
      0x00000402, 0x00000000, 0x00100002, 0x04100400,
      0x04000400, 0x04100002, 0x04100402, 0x00100000,
      0x04100002, 0x00000402, 0x00100000, 0x04000002,
      0x00100400, 0x04000400, 0x00000002, 0x04100000,
      0x04000402, 0x00000000, 0x00000400, 0x00100002,
      0x00000000, 0x04100002, 0x04100400, 0x00000400,
      0x04000000, 0x04100402, 0x00100402, 0x00100000,
      0x04100402, 0x00000002, 0x04000400, 0x00100402,
      0x00100002, 0x00100400, 0x04100000, 0x04000402,
      0x00000402, 0x04000000, 0x04000002, 0x04100400,
      ];
use constant des_SPtrans_4 =>
    [ # Nibble 4
      0x02000000, 0x00004000, 0x00000100, 0x02004108,
      0x02004008, 0x02000100, 0x00004108, 0x02004000,
      0x00004000, 0x00000008, 0x02000008, 0x00004100,
      0x02000108, 0x02004008, 0x02004100, 0x00000000,
      0x00004100, 0x02000000, 0x00004008, 0x00000108,
      0x02000100, 0x00004108, 0x00000000, 0x02000008,
      0x00000008, 0x02000108, 0x02004108, 0x00004008,
      0x02004000, 0x00000100, 0x00000108, 0x02004100,
      0x02004100, 0x02000108, 0x00004008, 0x02004000,
      0x00004000, 0x00000008, 0x02000008, 0x02000100,
      0x02000000, 0x00004100, 0x02004108, 0x00000000,
      0x00004108, 0x02000000, 0x00000100, 0x00004008,
      0x02000108, 0x00000100, 0x00000000, 0x02004108,
      0x02004008, 0x02004100, 0x00000108, 0x00004000,
      0x00004100, 0x02004008, 0x02000100, 0x00000108,
      0x00000008, 0x00004108, 0x02004000, 0x02000008,
      ];
use constant des_SPtrans_5 =>
    [ # Nibble 5
      0x20000010, 0x00080010, 0x00000000, 0x20080800,
      0x00080010, 0x00000800, 0x20000810, 0x00080000,
      0x00000810, 0x20080810, 0x00080800, 0x20000000,
      0x20000800, 0x20000010, 0x20080000, 0x00080810,
      0x00080000, 0x20000810, 0x20080010, 0x00000000,
      0x00000800, 0x00000010, 0x20080800, 0x20080010,
      0x20080810, 0x20080000, 0x20000000, 0x00000810,
      0x00000010, 0x00080800, 0x00080810, 0x20000800,
      0x00000810, 0x20000000, 0x20000800, 0x00080810,
      0x20080800, 0x00080010, 0x00000000, 0x20000800,
      0x20000000, 0x00000800, 0x20080010, 0x00080000,
      0x00080010, 0x20080810, 0x00080800, 0x00000010,
      0x20080810, 0x00080800, 0x00080000, 0x20000810,
      0x20000010, 0x20080000, 0x00080810, 0x00000000,
      0x00000800, 0x20000010, 0x20000810, 0x20080800,
      0x20080000, 0x00000810, 0x00000010, 0x20080010,
      ];
use constant des_SPtrans_6 =>
    [ # Nibble 6
      0x00001000, 0x00000080, 0x00400080, 0x00400001,
      0x00401081, 0x00001001, 0x00001080, 0x00000000,
      0x00400000, 0x00400081, 0x00000081, 0x00401000,
      0x00000001, 0x00401080, 0x00401000, 0x00000081,
      0x00400081, 0x00001000, 0x00001001, 0x00401081,
      0x00000000, 0x00400080, 0x00400001, 0x00001080,
      0x00401001, 0x00001081, 0x00401080, 0x00000001,
      0x00001081, 0x00401001, 0x00000080, 0x00400000,
      0x00001081, 0x00401000, 0x00401001, 0x00000081,
      0x00001000, 0x00000080, 0x00400000, 0x00401001,
      0x00400081, 0x00001081, 0x00001080, 0x00000000,
      0x00000080, 0x00400001, 0x00000001, 0x00400080,
      0x00000000, 0x00400081, 0x00400080, 0x00001080,
      0x00000081, 0x00001000, 0x00401081, 0x00400000,
      0x00401080, 0x00000001, 0x00001001, 0x00401081,
      0x00400001, 0x00401080, 0x00401000, 0x00001001,
      ];
use constant des_SPtrans_7 =>
    [ # Nibble 7
      0x08200020, 0x08208000, 0x00008020, 0x00000000,
      0x08008000, 0x00200020, 0x08200000, 0x08208020,
      0x00000020, 0x08000000, 0x00208000, 0x00008020,
      0x00208020, 0x08008020, 0x08000020, 0x08200000,
      0x00008000, 0x00208020, 0x00200020, 0x08008000,
      0x08208020, 0x08000020, 0x00000000, 0x00208000,
      0x08000000, 0x00200000, 0x08008020, 0x08200020,
      0x00200000, 0x00008000, 0x08208000, 0x00000020,
      0x00200000, 0x00008000, 0x08000020, 0x08208020,
      0x00008020, 0x08000000, 0x00000000, 0x00208000,
      0x08200020, 0x08008020, 0x08008000, 0x00200020,
      0x08208000, 0x00000020, 0x00200020, 0x08008000,
      0x08208020, 0x00200000, 0x08200000, 0x08000020,
      0x00208000, 0x00008020, 0x08008020, 0x08200000,
      0x00000020, 0x08208000, 0x00208020, 0x00000000,
      0x08000000, 0x08200020, 0x00008000, 0x00208020,
      ];

# These have also been split up.
use constant des_skb_0 =>
    [ # For C bits (numbered as per FIPS 46) 1 2 3 4 5 6.
      0x00000000, 0x00000010, 0x20000000, 0x20000010,
      0x00010000, 0x00010010, 0x20010000, 0x20010010,
      0x00000800, 0x00000810, 0x20000800, 0x20000810,
      0x00010800, 0x00010810, 0x20010800, 0x20010810,
      0x00000020, 0x00000030, 0x20000020, 0x20000030,
      0x00010020, 0x00010030, 0x20010020, 0x20010030,
      0x00000820, 0x00000830, 0x20000820, 0x20000830,
      0x00010820, 0x00010830, 0x20010820, 0x20010830,
      0x00080000, 0x00080010, 0x20080000, 0x20080010,
      0x00090000, 0x00090010, 0x20090000, 0x20090010,
      0x00080800, 0x00080810, 0x20080800, 0x20080810,
      0x00090800, 0x00090810, 0x20090800, 0x20090810,
      0x00080020, 0x00080030, 0x20080020, 0x20080030,
      0x00090020, 0x00090030, 0x20090020, 0x20090030,
      0x00080820, 0x00080830, 0x20080820, 0x20080830,
      0x00090820, 0x00090830, 0x20090820, 0x20090830,
      ];
use constant des_skb_1 =>
    [ # For C bits (numbered as per FIPS 46) 7 8 10 11 12 13
      0x00000000, 0x02000000, 0x00002000, 0x02002000,
      0x00200000, 0x02200000, 0x00202000, 0x02202000,
      0x00000004, 0x02000004, 0x00002004, 0x02002004,
      0x00200004, 0x02200004, 0x00202004, 0x02202004,
      0x00000400, 0x02000400, 0x00002400, 0x02002400,
      0x00200400, 0x02200400, 0x00202400, 0x02202400,
      0x00000404, 0x02000404, 0x00002404, 0x02002404,
      0x00200404, 0x02200404, 0x00202404, 0x02202404,
      0x10000000, 0x12000000, 0x10002000, 0x12002000,
      0x10200000, 0x12200000, 0x10202000, 0x12202000,
      0x10000004, 0x12000004, 0x10002004, 0x12002004,
      0x10200004, 0x12200004, 0x10202004, 0x12202004,
      0x10000400, 0x12000400, 0x10002400, 0x12002400,
      0x10200400, 0x12200400, 0x10202400, 0x12202400,
      0x10000404, 0x12000404, 0x10002404, 0x12002404,
      0x10200404, 0x12200404, 0x10202404, 0x12202404,
      ];
use constant des_skb_2 =>
    [ # For C bits (numbered as per FIPS 46) 14 15 16 17 19 20
      0x00000000, 0x00000001, 0x00040000, 0x00040001,
      0x01000000, 0x01000001, 0x01040000, 0x01040001,
      0x00000002, 0x00000003, 0x00040002, 0x00040003,
      0x01000002, 0x01000003, 0x01040002, 0x01040003,
      0x00000200, 0x00000201, 0x00040200, 0x00040201,
      0x01000200, 0x01000201, 0x01040200, 0x01040201,
      0x00000202, 0x00000203, 0x00040202, 0x00040203,
      0x01000202, 0x01000203, 0x01040202, 0x01040203,
      0x08000000, 0x08000001, 0x08040000, 0x08040001,
      0x09000000, 0x09000001, 0x09040000, 0x09040001,
      0x08000002, 0x08000003, 0x08040002, 0x08040003,
      0x09000002, 0x09000003, 0x09040002, 0x09040003,
      0x08000200, 0x08000201, 0x08040200, 0x08040201,
      0x09000200, 0x09000201, 0x09040200, 0x09040201,
      0x08000202, 0x08000203, 0x08040202, 0x08040203,
      0x09000202, 0x09000203, 0x09040202, 0x09040203,
      ];
use constant des_skb_3 =>
    [ # For C bits (numbered as per FIPS 46) 21 23 24 26 27 28
      0x00000000, 0x00100000, 0x00000100, 0x00100100,
      0x00000008, 0x00100008, 0x00000108, 0x00100108,
      0x00001000, 0x00101000, 0x00001100, 0x00101100,
      0x00001008, 0x00101008, 0x00001108, 0x00101108,
      0x04000000, 0x04100000, 0x04000100, 0x04100100,
      0x04000008, 0x04100008, 0x04000108, 0x04100108,
      0x04001000, 0x04101000, 0x04001100, 0x04101100,
      0x04001008, 0x04101008, 0x04001108, 0x04101108,
      0x00020000, 0x00120000, 0x00020100, 0x00120100,
      0x00020008, 0x00120008, 0x00020108, 0x00120108,
      0x00021000, 0x00121000, 0x00021100, 0x00121100,
      0x00021008, 0x00121008, 0x00021108, 0x00121108,
      0x04020000, 0x04120000, 0x04020100, 0x04120100,
      0x04020008, 0x04120008, 0x04020108, 0x04120108,
      0x04021000, 0x04121000, 0x04021100, 0x04121100,
      0x04021008, 0x04121008, 0x04021108, 0x04121108,
      ];
use constant des_skb_4 =>
    [ # For D bits (numbered as per FIPS 46) 1 2 3 4 5 6
      0x00000000, 0x10000000, 0x00010000, 0x10010000,
      0x00000004, 0x10000004, 0x00010004, 0x10010004,
      0x20000000, 0x30000000, 0x20010000, 0x30010000,
      0x20000004, 0x30000004, 0x20010004, 0x30010004,
      0x00100000, 0x10100000, 0x00110000, 0x10110000,
      0x00100004, 0x10100004, 0x00110004, 0x10110004,
      0x20100000, 0x30100000, 0x20110000, 0x30110000,
      0x20100004, 0x30100004, 0x20110004, 0x30110004,
      0x00001000, 0x10001000, 0x00011000, 0x10011000,
      0x00001004, 0x10001004, 0x00011004, 0x10011004,
      0x20001000, 0x30001000, 0x20011000, 0x30011000,
      0x20001004, 0x30001004, 0x20011004, 0x30011004,
      0x00101000, 0x10101000, 0x00111000, 0x10111000,
      0x00101004, 0x10101004, 0x00111004, 0x10111004,
      0x20101000, 0x30101000, 0x20111000, 0x30111000,
      0x20101004, 0x30101004, 0x20111004, 0x30111004,
      ];
use constant des_skb_5 =>
    [ # For D bits (numbered as per FIPS 46) 8 9 11 12 13 14
      0x00000000, 0x08000000, 0x00000008, 0x08000008,
      0x00000400, 0x08000400, 0x00000408, 0x08000408,
      0x00020000, 0x08020000, 0x00020008, 0x08020008,
      0x00020400, 0x08020400, 0x00020408, 0x08020408,
      0x00000001, 0x08000001, 0x00000009, 0x08000009,
      0x00000401, 0x08000401, 0x00000409, 0x08000409,
      0x00020001, 0x08020001, 0x00020009, 0x08020009,
      0x00020401, 0x08020401, 0x00020409, 0x08020409,
      0x02000000, 0x0A000000, 0x02000008, 0x0A000008,
      0x02000400, 0x0A000400, 0x02000408, 0x0A000408,
      0x02020000, 0x0A020000, 0x02020008, 0x0A020008,
      0x02020400, 0x0A020400, 0x02020408, 0x0A020408,
      0x02000001, 0x0A000001, 0x02000009, 0x0A000009,
      0x02000401, 0x0A000401, 0x02000409, 0x0A000409,
      0x02020001, 0x0A020001, 0x02020009, 0x0A020009,
      0x02020401, 0x0A020401, 0x02020409, 0x0A020409,
      ];
use constant des_skb_6 =>
    [ # For D bits (numbered as per FIPS 46) 16 17 18 19 20 21
      0x00000000, 0x00000100, 0x00080000, 0x00080100,
      0x01000000, 0x01000100, 0x01080000, 0x01080100,
      0x00000010, 0x00000110, 0x00080010, 0x00080110,
      0x01000010, 0x01000110, 0x01080010, 0x01080110,
      0x00200000, 0x00200100, 0x00280000, 0x00280100,
      0x01200000, 0x01200100, 0x01280000, 0x01280100,
      0x00200010, 0x00200110, 0x00280010, 0x00280110,
      0x01200010, 0x01200110, 0x01280010, 0x01280110,
      0x00000200, 0x00000300, 0x00080200, 0x00080300,
      0x01000200, 0x01000300, 0x01080200, 0x01080300,
      0x00000210, 0x00000310, 0x00080210, 0x00080310,
      0x01000210, 0x01000310, 0x01080210, 0x01080310,
      0x00200200, 0x00200300, 0x00280200, 0x00280300,
      0x01200200, 0x01200300, 0x01280200, 0x01280300,
      0x00200210, 0x00200310, 0x00280210, 0x00280310,
      0x01200210, 0x01200310, 0x01280210, 0x01280310,
      ];
use constant des_skb_7 =>
    [ # For D bits (numbered as per FIPS 46) 22 23 24 25 27 28
      0x00000000, 0x04000000, 0x00040000, 0x04040000,
      0x00000002, 0x04000002, 0x00040002, 0x04040002,
      0x00002000, 0x04002000, 0x00042000, 0x04042000,
      0x00002002, 0x04002002, 0x00042002, 0x04042002,
      0x00000020, 0x04000020, 0x00040020, 0x04040020,
      0x00000022, 0x04000022, 0x00040022, 0x04040022,
      0x00002020, 0x04002020, 0x00042020, 0x04042020,
      0x00002022, 0x04002022, 0x00042022, 0x04042022,
      0x00000800, 0x04000800, 0x00040800, 0x04040800,
      0x00000802, 0x04000802, 0x00040802, 0x04040802,
      0x00002800, 0x04002800, 0x00042800, 0x04042800,
      0x00002802, 0x04002802, 0x00042802, 0x04042802,
      0x00000820, 0x04000820, 0x00040820, 0x04040820,
      0x00000822, 0x04000822, 0x00040822, 0x04040822,
      0x00002820, 0x04002820, 0x00042820, 0x04042820,
      0x00002822, 0x04002822, 0x00042822, 0x04042822,
      ];








sub expand_key ($) {
    my ($c, $d) = unpack "VV", shift;

    usage ("at least 8 byte key") unless defined $d;
    my @k = ();

    my ($t, $s);
    $t = (($d >> 4) ^ $c) & 0x0f0f0f0f;
    $c ^= $t;
    $d ^= $t << 4;
    $t = (($c << 18) ^ $c) & 0xcccc0000;
    $c = $c ^ $t ^ (($t >> 18) & 0x00003fff);
    $t = (($d << 18) ^ $d) & 0xcccc0000;
    $d = $d ^ $t ^ (($t >> 18) & 0x00003fff);
    $t = (($d >> 1) ^ $c) & 0x55555555;
    $c ^= $t;
    $d ^= $t << 1;
    $t = (($c >> 8) ^ $d) & 0x00ff00ff;
    $d ^= $t;
    $c ^= $t << 8;
    $t = (($d >> 1) ^ $c) & 0x55555555;
    $c ^= $t;
    $d ^= $t << 1;
    $d =     ((($d & 0x000000ff) << 16) |  ($d & 0x0000ff00)     |
	      (($d >> 16) & 0x000000ff) | (($c >> 4) & 0x0f000000));
    $c &= 0x0fffffff;

    use constant shifts2 => [0, 0, 1, 1, 1, 1, 1, 1,
			     0, 1, 1, 1, 1, 1, 1, 0];

    # Do not try to unroll any of the loops (not this one and not the
    # one in crypt().  It will make things slower (about 30 %!).
    foreach my $i (0 .. ITERATIONS - 1) {
	# No need to mask out the sign here because only the
	# lower 28 bits are used.
	if (shifts2->[$i]) {
	    $c = (($c >> 2) | ($c << 26));
	    $d = (($d >> 2) | ($d << 26));
	} else {
	    $c= (($c >> 1) | ($c << 27));
	    $d= (($d >> 1) | ($d << 27));
	}
	$c &= 0x0fffffff;
	$d &= 0x0fffffff;

	$s = (des_skb_0->[($c) & 0x3f] |
	      des_skb_1->[(($c >>  6) & 0x03) |
			  (($c >>  7) & 0x3c)] |
	      des_skb_2->[(($c >> 13) & 0x0f) |
			  (($c >> 14) & 0x30)] |
	      des_skb_3->[(($c >> 20) & 0x01) |
			  (($c >> 21) & 0x06) |
			  (($c >> 22) & 0x38)]);
	$t = (des_skb_4->[($d) & 0x3f] |
	      des_skb_5->[(($d >>  7) & 0x03) |
			  (($d >>  8) & 0x3c)] |
	      des_skb_6->[ ($d >> 15) & 0x3f] |
	      des_skb_7->[(($d >> 21) & 0x0f) |
			  (($d >> 22) & 0x30)]);

	$k[$i << 1] = (($t << 16) | ($s & 0x0000ffff)) & 0xffffffff;
	$s = ((($s >> 16) & 0x0000ffff) | ($t & 0xffff0000));

	$s = ($s << 4) | (($s >> 28) & 0x0fffffff);
	$k[($i << 1) + 1] = $s & 0xffffffff;
    }
    pack ("V*", @k);
}


sub crypt ($$$) {
    my ($input, $ks, $encrypt) = @_;
    my $output;

    my ($t, $u);

    my ($l, $r) = unpack "VV", $input;
    usage ("at least 8 byte key") unless defined $r;

    $t = (($r >> 4) ^ $l) & 0x0f0f0f0f;
    $l ^= $t;
    $r ^= $t << 4;
    $t = (($l >> 16) ^ $r) & 0x0000ffff;
    $r ^= $t;
    $l ^= $t << 16;
    $t = (($r >> 2) ^ $l) & 0x33333333;
    $l ^= $t;
    $r ^= $t << 2;
    $t = (($l >> 8) ^ $r) & 0x00ff00ff;
    $r ^= $t;
    $l ^= $t << 8;
    $t = (($r >> 1) ^ $l) & 0x55555555;
    $l ^= $t;
    $r ^= $t << 1;

    $t = ($r << 1) | (($r >> 31) & 0x1);
    $r = ($l << 1) | (($l >> 31) & 0x1);
    $l = $t;

    # Clear the top bits on machines with 8byte longs.
    $l &= 0xffffffff;
    $r &= 0xffffffff;

    my @s = unpack ("V32", $ks);
    my $i;

    if ($encrypt) {
	for ($i = 0; $i < 32; $i += 4) {
	    $u  = ($r ^ $s[($i + 0)    ]);
	    $t =   $r ^ $s[($i + 0) + 1];
	    $t = (($t >> 4) & 0x0fffffff) | ($t << 28);
	    $l ^= des_SPtrans_1->[($t      ) & 0x3f]|
	          des_SPtrans_3->[($t >>  8) & 0x3f]|
	          des_SPtrans_5->[($t >> 16) & 0x3f]|
	          des_SPtrans_7->[($t >> 24) & 0x3f]|
	          des_SPtrans_0->[($u      ) & 0x3f]|
	          des_SPtrans_2->[($u >>  8) & 0x3f]|
	          des_SPtrans_4->[($u >> 16) & 0x3f]|
	          des_SPtrans_6->[($u >> 24) & 0x3f];
	    $u  = ($l ^ $s[($i + 2)    ]);
	    $t =   $l ^ $s[($i + 2) + 1];
	    $t = (($t >> 4) & 0x0fffffff) | ($t << 28);
	    $r ^= des_SPtrans_1->[($t      ) & 0x3f]|
	          des_SPtrans_3->[($t >>  8) & 0x3f]|
	          des_SPtrans_5->[($t >> 16) & 0x3f]|
	          des_SPtrans_7->[($t >> 24) & 0x3f]|
	          des_SPtrans_0->[($u      ) & 0x3f]|
	          des_SPtrans_2->[($u >>  8) & 0x3f]|
	          des_SPtrans_4->[($u >> 16) & 0x3f]|
	          des_SPtrans_6->[($u >> 24) & 0x3f];
	}
    } else {
	for ($i = 30; $i > 0; $i -= 4) {
	    $u  = ($r ^ $s[($i - 0)    ]);
	    $t =   $r ^ $s[($i - 0) + 1];
	    $t = (($t >> 4) & 0x0fffffff) | ($t << 28);
	    $l ^= des_SPtrans_1->[($t      ) & 0x3f]|
	          des_SPtrans_3->[($t >>  8) & 0x3f]|
	          des_SPtrans_5->[($t >> 16) & 0x3f]|
	          des_SPtrans_7->[($t >> 24) & 0x3f]|
	          des_SPtrans_0->[($u      ) & 0x3f]|
	          des_SPtrans_2->[($u >>  8) & 0x3f]|
	          des_SPtrans_4->[($u >> 16) & 0x3f]|
	          des_SPtrans_6->[($u >> 24) & 0x3f];
	    $u  = ($l ^ $s[($i - 2)    ]);
	    $t =   $l ^ $s[($i - 2) + 1];
	    $t = (($t >> 4) & 0x0fffffff) | ($t << 28);
	    $r ^= des_SPtrans_1->[($t      ) & 0x3f]|
	          des_SPtrans_3->[($t >>  8) & 0x3f]|
	          des_SPtrans_5->[($t >> 16) & 0x3f]|
	          des_SPtrans_7->[($t >> 24) & 0x3f]|
	          des_SPtrans_0->[($u      ) & 0x3f]|
	          des_SPtrans_2->[($u >>  8) & 0x3f]|
	          des_SPtrans_4->[($u >> 16) & 0x3f]|
	          des_SPtrans_6->[($u >> 24) & 0x3f];
	}
    }

    $l = (($l >> 1) & 0x7fffffff) | ($l << 31);
    $r = (($r >> 1) & 0x7fffffff) | ($r << 31);
    # Clear the top bits on machines with 8byte longs.
    $l &= 0xffffffff;
    $r &= 0xffffffff;

    # Swap $l and $r.
    # We will not do the swap so just remember they are
    # Reversed for the rest of the subroutine
    # Luckily FP fixes this problem :-)

    $t = (($r >> 1) ^ $l) & 0x55555555;
    $l ^= $t;
    $r ^= $t << 1;
    $t = (($l >> 8) ^ $r) & 0x00ff00ff;
    $r ^= $t;
    $l ^= $t << 8;
    $t = (($r >> 2) ^ $l) & 0x33333333;
    $l ^= $t;
    $r ^= $t << 2;
    $t = (($l >> 16) ^ $r) & 0x0000ffff;
    $r ^= $t;
    $l ^= $t << 16;
    $t = (($r >> 4) ^ $l) & 0x0f0f0f0f;
    $l ^= $t;
    $r ^= $t << 4;

    pack "VV", $l, $r;
}

1;

__END__