package Crypt::UnixCrypt;

use 5.004;  # i.e. not tested under earlier versions
use strict;
use vars qw($VERSION @ISA @EXPORT $OVERRIDE_BUILTIN);

$VERSION = '1.0';

require Exporter;
@ISA = qw(Exporter);

# Don't override built-in crypt() unless forced to to so
use Config;
@EXPORT = qw(crypt)
	if !defined $Config{d_crypt} ||
	   (defined $OVERRIDE_BUILTIN && $OVERRIDE_BUILTIN);


my $ITERATIONS = 16;

my @con_salt =
(
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 
	0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 
	0x0A, 0x0B, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 
	0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, 
	0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 
	0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, 
	0x23, 0x24, 0x25, 0x20, 0x21, 0x22, 0x23, 0x24, 
	0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 
	0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, 
	0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, 
	0x3D, 0x3E, 0x3F, 0x00, 0x00, 0x00, 0x00, 0x00, 
);

my @shifts2 =
(
	0, 0, 1, 1, 1, 1, 1, 1,
	0, 1, 1, 1, 1, 1, 1, 0
);

my @skb0 =
(
	# 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, 
);
my @skb1 =
(
	# 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, 
);
my @skb2 =
(
	# 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, 
);
my @skb3 =
(
	# 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, 
);
my @skb4 =
(
	# 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, 
);
my @skb5 =
(
	# 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, 
);
my @skb6 =
(
	# 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, 
);
my @skb7 =
(
	# 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, 
);

my @SPtrans0 =
(
	# 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,
);
my @SPtrans1 =
(
	# 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,
);
my @SPtrans2 =
(
	# 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,
);
my @SPtrans3 =
(
	# 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,
);
my @SPtrans4 =
(
	# 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,
);
my @SPtrans5 =
(
	# 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,
);
my @SPtrans6 =
(
	# 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,
);
my @SPtrans7 =
(
	# 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
);

my @cov_2char =
(
	0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 
	0x36, 0x37, 0x38, 0x39, 0x41, 0x42, 0x43, 0x44, 
	0x45, 0x46, 0x47, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 
	0x4D, 0x4E, 0x4F, 0x50, 0x51, 0x52, 0x53, 0x54, 
	0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x61, 0x62, 
	0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A, 
	0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71, 0x72, 
	0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A
);

sub ushr  # only for ints! (mimics the Java >>> operator)
{
	my ($n, $s) = @_;

	$s &= 0x1f;

	return( ($n >> $s) & (~0 >> $s) );
}

sub toByte
{
	my $value = shift;

	$value &= 0xff;
	$value = - ((~$value & 0xff) + 1)
		if $value & 0x80;

	return $value;
}

sub toInt
{
	my $value = shift;

	$value = - ((~$value & 0xffffffff) + 1)
		if $value & 0x80000000;

	return $value;
}

sub byteToUnsigned # int byteToUnsigned(byte b)
{
	my $value = shift;

	return( $value >= 0 ? $value : $value + 256 );
}

sub fourBytesToInt # int fourBytesToInt(byte b[], int offset)
{
	my ($b, $offset) = @_;
	my $value;

	$value  =  byteToUnsigned($b->[$offset++]);
	$value |= (byteToUnsigned($b->[$offset++]) <<  8);
	$value |= (byteToUnsigned($b->[$offset++]) << 16);
	$value |= (byteToUnsigned($b->[$offset++]) << 24);

	return toInt($value);
}

sub intToFourBytes # void intToFourBytes(int iValue, byte b[], int offset)
{
	my ($iValue, $b, $offset) = @_;

	$b->[$offset++] = toByte(ushr($iValue, 0) & 0xff);
	$b->[$offset++] = toByte(ushr($iValue, 8) & 0xff);
	$b->[$offset++] = toByte(ushr($iValue,16) & 0xff);
	$b->[$offset++] = toByte(ushr($iValue,24) & 0xff);

	return undef;
}

sub PERM_OP # void PERM_OP(int a, int b, int n, int m, int results[])
{
	my ($a, $b, $n, $m, $results) = @_;
	my $t;

	$t = (ushr($a,$n) ^ $b) & $m;
	$a ^= $t << $n;
	$b ^= $t;

	$results->[0] = toInt($a);
	$results->[1] = toInt($b);

	return undef;
}

sub HPERM_OP # void HPERM_OP(int a, int n, int m)
{
	my ($a, $n, $m) = @_;
	my $t;

	$t = (($a << (16 - $n)) ^ $a) & $m;
	$a = $a ^ $t ^ ushr($t, 16 - $n);

	return toInt($a);
}

sub des_set_key # int [] des_set_key(byte key[])
{
	my ($key) = @_;
	my @schedule; $#schedule = $ITERATIONS * 2 -1;

	my $c = fourBytesToInt($key, 0);
	my $d = fourBytesToInt($key, 4);

	my @results; $#results = 1;

	PERM_OP($d, $c, 4, 0x0f0f0f0f, \@results);
	$d = $results[0]; $c = $results[1];

	$c = HPERM_OP($c, -2, 0xcccc0000);
	$d = HPERM_OP($d, -2, 0xcccc0000);

	PERM_OP($d, $c, 1, 0x55555555, \@results);
	$d = $results[0]; $c = $results[1];

	PERM_OP($c, $d, 8, 0x00ff00ff, \@results);
	$c = $results[0]; $d = $results[1];

	PERM_OP($d, $c, 1, 0x55555555, \@results);
	$d = $results[0]; $c = $results[1];

	$d = (    (($d & 0x000000ff) << 16) |     ($d & 0x0000ff00)  |
	       ushr($d & 0x00ff0000,    16) | ushr($c & 0xf0000000, 4));
	$c &= 0x0fffffff;

	my ($s, $t);
	my ($i, $j);

	$j = 0;
	for($i = 0; $i < $ITERATIONS; $i++)
	{
		if($shifts2[$i])
		{
			$c = ushr($c, 2) | ($c << 26);
			$d = ushr($d, 2) | ($d << 26);
		}
		else
		{
			$c = ushr($c, 1) | ($c << 27);
			$d = ushr($d, 1) | ($d << 27);
		}

		$c &= 0x0fffffff;
		$d &= 0x0fffffff;

		$s = $skb0[     ($c   ) & 0x3f                        ]|
		     $skb1[(ushr($c, 6) & 0x03) | (ushr($c, 7) & 0x3c)]|
		     $skb2[(ushr($c,13) & 0x0f) | (ushr($c,14) & 0x30)]|
		     $skb3[(ushr($c,20) & 0x01) | (ushr($c,21) & 0x06) |
		                                  (ushr($c,22) & 0x38)];

		$t = $skb4[     ($d   ) & 0x3f                         ]|
		     $skb5[(ushr($d, 7) & 0x03) | (ushr($d, 8) & 0x3c) ]|
		     $skb6[ ushr($d,15) & 0x3f                         ]|
		     $skb7[(ushr($d,21) & 0x0f) | (ushr($d,22) & 0x30)];

		$schedule[$j++] = (    ($t << 16) | ($s & 0x0000ffff)) & 0xffffffff;
		$s              = (ushr($s,   16) | ($t & 0xffff0000));

		$s              = ($s << 4) | ushr($s,28);
		$schedule[$j++] = $s & 0xffffffff;
	}

	return \@schedule;
}

sub D_ENCRYPT # int D_ENCRYPT(int L, int R, int S, int E0, int E1, int s[])
{
	my ($L, $R, $S, $E0, $E1, $s) = @_;
	my ($t, $u, $v);

	$v = $R ^ ushr($R,16);
	$u = $v & $E0;
	$v = $v & $E1;
	$u = ($u ^ ($u << 16)) ^ $R ^ $s->[$S];
	$t = ($v ^ ($v << 16)) ^ $R ^ $s->[$S + 1];
	$t = ushr($t, 4) | ($t << 28);

	$L ^= $SPtrans1[    ($t    ) & 0x3f] |
	      $SPtrans3[ushr($t,  8) & 0x3f] |
	      $SPtrans5[ushr($t, 16) & 0x3f] |
	      $SPtrans7[ushr($t, 24) & 0x3f] |
	      $SPtrans0[    ($u    ) & 0x3f] |
	      $SPtrans2[ushr($u,  8) & 0x3f] |
	      $SPtrans4[ushr($u, 16) & 0x3f] |
	      $SPtrans6[ushr($u, 24) & 0x3f];

	return $L;
}

sub body # int [] body(int schedule[], int Eswap0, int Eswap1)
{
	my ($schedule, $Eswap0, $Eswap1) = @_;
	my $left  = 0;
	my $right = 0;
	my $t     = 0;

	my ($i, $j);
	for($j = 0; $j < 25; $j++)
	{
		for($i = 0; $i < $ITERATIONS * 2; $i += 4)
		{
			$left  = D_ENCRYPT($left,  $right, $i,     $Eswap0, $Eswap1, $schedule);
			$right = D_ENCRYPT($right, $left,  $i + 2, $Eswap0, $Eswap1, $schedule);
		}
		$t     = $left; 
		$left  = $right; 
		$right = $t;
	}

	$t = $right;

	$right = ushr($left, 1) | ($left << 31);
	$left  = ushr($t   , 1) | ($t    << 31);

	$left  &= 0xffffffff;
	$right &= 0xffffffff;

	my @results; $#results = 1;

	PERM_OP($right, $left, 1, 0x55555555, \@results); 
	$right = $results[0]; $left = $results[1];

	PERM_OP($left, $right, 8, 0x00ff00ff, \@results); 
	$left = $results[0]; $right = $results[1];

	PERM_OP($right, $left, 2, 0x33333333, \@results); 
	$right = $results[0]; $left = $results[1];

	PERM_OP($left, $right, 16, 0x0000ffff, \@results);
	$left = $results[0]; $right = $results[1];

	PERM_OP($right, $left, 4, 0x0f0f0f0f, \@results);
	$right = $results[0]; $left = $results[1];

	my @out; $#out = 1;

	$out[0] = $left; $out[1] = $right;

	return \@out;
}

sub crypt($$) # String crypt(String plaintext, String salt)
{
	my ($plaintext, $salt) = @_;
	my $buffer = '';

	return $buffer if !defined $salt || $salt eq '';

	$salt .= $salt if length $salt < 2;
	$plaintext = '' if !defined $plaintext;
 
	$buffer = substr $salt,0,2;

	my $Eswap0 = $con_salt[ord(substr $salt,0,1)];
	my $Eswap1 = $con_salt[ord(substr $salt,1,1)] << 4;

	my @key;
	@key[0..7] = (0) x 8;

	my @iChar = map { ord($_) << 1 } split(//, $plaintext);
	my $i;
	for (my $i = 0; $i < @key && $i < @iChar; $i++) {
		$key[$i] = toByte($iChar[$i]);
	}

	my $schedule = des_set_key(\@key);
	my $out      = body($schedule, $Eswap0, $Eswap1);

	my @b; $#b = 8;

	intToFourBytes($out->[0], \@b, 0);
	intToFourBytes($out->[1], \@b, 4);
	$b[8] = 0;

	my ($j, $c, $y, $u);
	for($i = 2, $y = 0, $u = 0x80; $i < 13; $i++)
	{
		for($j = 0, $c = 0; $j < 6; $j++)
		{
			$c <<= 1;

			$c |= 1 if ($b[$y] & $u) != 0;

			$u >>= 1;

			if($u == 0)
			{
				$y++;
				$u = 0x80;
			}
		}
		$buffer .= chr($cov_2char[$c]);
	}

	return $buffer;
}

1;
__END__

=head1 NAME

Crypt::UnixCrypt - perl-only implementation of the C<crypt> function.

=head1 SYNOPSIS

  use Crypt::UnixCrypt;
  $hashed = crypt($plaintext,$salt);

  # always use this module's crypt
  BEGIN { $Crypt::UnixCrpyt::OVERRIDE_BUILTIN = 1 }
  use Crypt::UnixCrypt;

=head1 DESCRIPTION

This module is for all those poor souls whose perl port answers to the
use of C<crypt()> with the message `The crypt() function is unimplemented
due to excessive paranoia.'.

This module won't overload a built-in C<crypt()> unless forced by a true
value of the variable C<$Crypt::UnixCrypt::OVERRIDE_BUILTIN>.

If you use this module, you probably neither have a built-in C<crypt()>
function nor a L<crypt(3)> manpage; so I'll supply the appropriate portions
of its description (from my Linux system) here:

crypt is the password encryption function. It is based on the Data
Encryption Standard algorithm with variations intended (among other
things) to discourage use of hardware implementations of a key search.

$plaintext is a user's typed password.

$salt is a two-character string chosen from the set [a-zA-Z0-9./]. This
string is used to perturb the algorithm in one of 4096 different ways.

By taking the lowest 7 bit of each character of $plaintext (filling it up
to 8 characters with zeros, if needed), a 56-bit key is obtained. This
56-bit key is used to encrypt repeatedly a constant string (usually a
string consisting of all zeros). The returned value points to the
encrypted password, a series of 13 printable ASCII characters (the first
two characters represent the salt itself).

Warning: The key space consists of 2**56 equal 7.2e16 possible values.
Exhaustive searches of this key space are possible using massively
parallel computers. Software, such as crack(1), is available which will
search the portion of this key space that is generally used by humans
for passwords. Hence, password selection should, at minimum, avoid
common words and names. The use of a passwd(1) program that checks for
crackable passwords during the selection process is recommended.

The DES algorithm itself has a few quirks which make the use of the
crypt(3) interface a very poor choice for anything other than password
authentication. If you are planning on using the crypt(3) interface for
a cryptography project, don't do it: get a good book on encryption and
one of the widely available DES libraries.

=head1 COPYRIGHT

This module is free software; you may redistribute it and/or modify it
under the same terms as Perl itself.

=head1 AUTHORS

Written by Martin Vorlaender, martin@radiogaga.harz.de, 11-DEC-1997.
Based upon Java source code written by jdumas@zgs.com, which in turn is
based upon C source code written by Eric Young, eay@psych.uq.oz.au.

=head1 CAVEATS

In extreme situations, this function doesn't behave like C<crypt(3)>,
e.g. when called with a salt not in [A-Za-z0-9./]{2}.

=head1 SEE ALSO

perl(1), perlfunc(1), crypt(3).