File Coverage

blib/lib/Crypt/Twofish_PP.pm

Criterion	Covered	Total	%
statement	300	318	94.3
branch	11	16	68.7
condition	5	6	83.3
subroutine	9	14	64.2
pod	5	6	83.3
total	330	360	91.6

#! /bin/false

# vim: tabstop=4
# $Id: Twofish_PP.pm,v 1.8 2003/11/27 15:28:41 guido Exp $

# Twofish in pure Perl.
# Copyright (C) 2003 Guido Flohr , all rights reserved.

# This program is free software; you can redistribute it and/or modify it
# under the same terms and conditions as Perl itsels (see the Artistic
# license included).

package Crypt::Twofish_PP;

use strict;
use integer;

use Locale::TextDomain qw (Crypt-Twofish_PP);

use vars qw ($VERSION);

$VERSION = '0.17';

my @q0 = (
	  169, 103, 179, 232, 4, 253, 163, 118, 154, 146, 128, 120, 228, 221, 209,
	  56, 13, 198, 53, 152, 24, 247, 236, 108, 67, 117, 55, 38, 250, 19, 148,
	  72, 242, 208, 139, 48, 132, 84, 223, 35, 25, 91, 61, 89, 243, 174, 162,
	  130, 99, 1, 131, 46, 217, 81, 155, 124, 166, 235, 165, 190, 22, 12, 227,
	  97, 192, 140, 58, 245, 115, 44, 37, 11, 187, 78, 137, 107, 83, 106, 180,
	  241, 225, 230, 189, 69, 226, 244, 182, 102, 204, 149, 3, 86, 212, 28, 30,
	  215, 251, 195, 142, 181, 233, 207, 191, 186, 234, 119, 57, 175, 51, 201,
	  98, 113, 129, 121, 9, 173, 36, 205, 249, 216, 229, 197, 185, 77, 68, 8,
	  134, 231, 161, 29, 170, 237, 6, 112, 178, 210, 65, 123, 160, 17, 49, 194,
	  39, 144, 32, 246, 96, 255, 150, 92, 177, 171, 158, 156, 82, 27, 95, 147,
	  10, 239, 145, 133, 73, 238, 45, 79, 143, 59, 71, 135, 109, 70, 214, 62,
	  105, 100, 42, 206, 203, 47, 252, 151, 5, 122, 172, 127, 213, 26, 75, 14,
	  167, 90, 40, 20, 63, 41, 136, 60, 76, 2, 184, 218, 176, 23, 85, 31, 138,
	  125, 87, 199, 141, 116, 183, 196, 159, 114, 126, 21, 34, 18, 88, 7, 153,
	  52, 110, 80, 222, 104, 101, 188, 219, 248, 200, 168, 43, 64, 220, 254,
	  50, 164, 202, 16, 33, 240, 211, 93, 15, 0, 111, 157, 54, 66, 74, 94, 193,
	  224
		   );
my @q1 = (
	  117, 243, 198, 244, 219, 123, 251, 200, 74, 211, 230, 107, 69, 125, 232,
	  75, 214, 50, 216, 253, 55, 113, 241, 225, 48, 15, 248, 27, 135, 250, 6,
	  63, 94, 186, 174, 91, 138, 0, 188, 157, 109, 193, 177, 14, 128, 93, 210,
	  213, 160, 132, 7, 20, 181, 144, 44, 163, 178, 115, 76, 84, 146, 116, 54,
	  81, 56, 176, 189, 90, 252, 96, 98, 150, 108, 66, 247, 16, 124, 40, 39,
	  140, 19, 149, 156, 199, 36, 70, 59, 112, 202, 227, 133, 203, 17, 208,
	  147, 184, 166, 131, 32, 255, 159, 119, 195, 204, 3, 111, 8, 191, 64, 231,
	  43, 226, 121, 12, 170, 130, 65, 58, 234, 185, 228, 154, 164, 151, 126,
	  218, 122, 23, 102, 148, 161, 29, 61, 240, 222, 179, 11, 114, 167, 28,
	  239, 209, 83, 62, 143, 51, 38, 95, 236, 118, 42, 73, 129, 136, 238, 33,
	  196, 26, 235, 217, 197, 57, 153, 205, 173, 49, 139, 1, 24, 35, 221, 31,
	  78, 45, 249, 72, 79, 242, 101, 142, 120, 92, 88, 25, 141, 229, 152, 87,
	  103, 127, 5, 100, 175, 99, 182, 254, 245, 183, 60, 165, 206, 233, 104,
	  68, 224, 77, 67, 105, 41, 46, 172, 21, 89, 168, 10, 158, 110, 71, 223,
	  52, 53, 106, 207, 220, 34, 201, 192, 155, 137, 212, 237, 171, 18, 162,
	  13, 82, 187, 2, 47, 169, 215, 97, 30, 180, 80, 4, 246, 194, 22, 37, 134,
	  86, 85, 9, 190, 145
	 );

my @m0 =
	(
	  3166450293, 3974898163, 538985414, 3014904308, 3671720923,
	  33721211, 3806473211, 2661219016, 3385453642, 3570665939,
	  404253670, 505323371, 2560101957, 2998024317, 2795950824,
	  640071499, 1010587606, 2475919922, 2189618904, 1381144829,
	  2071712823, 3149608817, 1532729329, 1195869153, 606354480,
	  1364320783, 3132802808, 1246425883, 3216984199, 218984698,
	  2964370182, 1970658879, 3537042782, 2105352378, 1717973422,
	  976921435, 1499012234, 0, 3452801980, 437969053, 2930650221,
	  2139073473, 724289457, 3200170254, 3772817536, 2324303965,
	  993743570, 1684323029, 3638069408, 3890718084, 1600120839,
	  454758676, 741130933, 4244419728, 825304876, 2155898275,
	  1936927410, 202146163, 2037997388, 1802191188, 1263207058,
	  1397975412, 2492763958, 2206408529, 707409464, 3301219504,
	  572704957, 3587569754, 3183330300, 1212708960, 4294954594,
	  1280051094, 1094809452, 3351766594, 3958056183, 471602192,
	  1566401404, 909517352, 1734852647, 3924406156, 1145370899,
	  336915093, 4126522268, 3486456007, 1061104932, 3233866566,
	  1920129851, 1414818928, 690572490, 4042274275, 134807173,
	  3334870987, 4092808977, 2358043856, 2762234259, 3402274488,
	  1751661478, 3099086211, 943204384, 3857002239, 2913818271,
	  185304183, 3368558019, 2577006540, 1482222851, 421108335,
	  235801096, 2509602495, 1886408768, 4160172263, 1852755755,
	  522153698, 3048553849, 151588620, 1633760426, 1465325186,
	  2678000449, 2644344890, 286352618, 623234489, 2947538404,
	  1162152090, 3755969956, 2745392279, 3941258622, 892688602,
	  3991785594, 1128528919, 4177054566, 4227576212, 926405537,
	  4210704413, 3267520573, 3031747824, 842161630, 2627498419,
	  1448535819, 3823360626, 2273796263, 353704732, 4193860335,
	  1667481553, 875866451, 2593817918, 2981184143, 2088554803,
	  2290653990, 1027450463, 2711738348, 3840204662, 2172752938,
	  2442199369, 252705665, 4008618632, 370565614, 3621221153,
	  2543318468, 2779097114, 4278075371, 1835906521, 2021174981,
	  3318050105, 488498585, 1987486925, 1044307117, 3419105073,
	  3065399179, 4025441025, 303177240, 1616954659, 1785376989,
	  1296954911, 3469666638, 3739122733, 1431674361, 2122209864,
	  555856463, 50559730, 2694850149, 1583225230, 1515873912,
	  1701137244, 1650609752, 4261233945, 101119117, 1077970661,
	  4075994776, 859024471, 387420263, 84250239, 3907542533,
	  1330609508, 2307484335, 269522275, 1953771446, 168457726,
	  1549570805, 2610656439, 757936956, 808507045, 774785486,
	  1229556201, 1179021928, 2004309316, 2829637856, 2526413901,
	  673758531, 2846435689, 3654908201, 2256965934, 3520169900,
	  4109650453, 2374833497, 3604382376, 3115957258, 1111625118,
	  4143366510, 791656519, 3722249951, 589510964, 3435946549,
	  4059153514, 3250655951, 2240146396, 2408554018, 1903272393,
	  2425417920, 2863289243, 16904585, 2341200340, 1313770733,
	  2391699371, 2880152082, 1869561506, 3873854477, 3688624722,
	  2459073467, 3082270210, 1768540719, 960092585, 3553823959,
	  2812748641, 2728570142, 3284375988, 1819034704, 117900548,
	  67403766, 656885442, 2896996118, 3503322661, 1347425158,
	  3705468758, 2223250005, 3789639945, 2054825406, 320073617
	  );

my @m1 =
	(
	  2849585465, 1737496343, 3010567324, 3906119334, 67438343,
	  4254618194, 2741338240, 1994384612, 2584233285, 2449623883,
	  2158026976, 2019973722, 3839733679, 3719326314, 3518980963,
	  943073834, 223667942, 3326287904, 895667404, 2562650866,
	  404623890, 4146392043, 3973554593, 1819754817, 1136470056,
	  1966259388, 936672123, 647727240, 4201647373, 335103044,
	  2494692347, 1213890174, 4068082435, 3504639116, 2336732854,
	  809247780, 2225465319, 1413573483, 3741769181, 600137824,
	  424017405, 1537423930, 1030275778, 1494584717, 4079086828,
	  2922473062, 2722000751, 2182502231, 1670713360, 22802415,
	  2202908856, 781289094, 3652545901, 1361019779, 2605951658,
	  2086886749, 2788911208, 3946839806, 2782277680, 3190127226,
	  380087468, 202311945, 3811963120, 1629726631, 3236991120,
	  2360338921, 981507485, 4120009820, 1937837068, 740766001,
	  628543696, 199710294, 3145437842, 1323945678, 2314273025,
	  1805590046, 1403597876, 1791291889, 3029976003, 4053228379,
	  3783477063, 3865778200, 3184009762, 1158584472, 3798867743,
	  4106859443, 3056563316, 1724643576, 3439303065, 2515145748,
	  65886296, 1459084508, 3571551115, 471536917, 514695842,
	  3607942099, 4213957346, 3273509064, 2384027230, 3049401388,
	  3918088521, 3474112961, 3212744085, 3122691453, 3932426513,
	  2005142283, 963495365, 2942994825, 869366908, 3382800753,
	  1657733119, 1899477947, 2180714255, 2034087349, 156361185,
	  2916892222, 606945087, 3450107510, 4187837781, 3639509634,
	  3850780736, 3316545656, 3117229349, 1292146326, 1146451831,
	  134876686, 2249412688, 3878746103, 2714974007, 490797818,
	  2855559521, 3985395278, 112439472, 1886147668, 2989126515,
	  3528604475, 1091280799, 2072707586, 2693322968, 290452467,
	  828885963, 3259377447, 666920807, 2427780348, 539506744,
	  4135519236, 1618495560, 4281263589, 2517060684, 1548445029,
	  2982619947, 2876214926, 2651669058, 2629563893, 1391647707,
	  468929098, 1604730173, 2472125604, 180140473, 4013619705,
	  2448364307, 2248017928, 1224839569, 3999340054, 763158238,
	  1337073953, 2403512753, 1004237426, 1203253039, 2269691839,
	  1831644846, 1189331136, 3596041276, 1048943258, 1764338089,
	  1685933903, 714375553, 3460902446, 3407333062, 801794409,
	  4240686525, 2539430819, 90106088, 2060512749, 2894582225,
	  2140013829, 3585762404, 447260069, 1270294054, 247054014,
	  2808121223, 1526257109, 673330742, 336665371, 1071543669,
	  695851481, 2292903662, 1009986861, 1281325433, 45529015,
	  3096890058, 3663213877, 2963064004, 402408259, 1427801220,
	  536235341, 2317113689, 2100867762, 1470903091, 3340292047,
	  2381579782, 1953059667, 3077872539, 3304429463, 2673257901,
	  1926947811, 2127948522, 357233908, 580816783, 312650667,
	  1481532002, 132669279, 2581929245, 876159779, 1858205430,
	  1346661484, 3730649650, 1752319558, 1697030304, 3163803085,
	  3674462938, 4173773498, 3371867806, 2827146966, 735014510,
	  1079013488, 3706422661, 4269083146, 847942547, 2760761311,
	  3393988905, 269753372, 561240023, 4039947444, 3540636884,
	  1561365130, 266490193, 0, 1872369945, 2648709658, 915379348,
	  1122420679, 1257032137, 1593692882, 3249241983, 3772295336
	 );

my @m2 =
	(
	  3161832498, 3975408673, 549855299, 3019158473, 3671841283,
	  41616011, 3808158251, 2663948026, 3377121772, 3570652169,
	  417732715, 510336671, 2554697742, 2994582072, 2800264914,
	  642459319, 1020673111, 2469565322, 2195227374, 1392333464,
	  2067233748, 3144792887, 1542544279, 1205946243, 607134780,
	  1359958498, 3136862918, 1243302643, 3213344584, 234491248,
	  2953228467, 1967093214, 3529429757, 2109373728, 1722705457,
	  979057315, 1502239004, 0, 3451702675, 446503648, 2926423596,
	  2143387563, 733031367, 3188637369, 3766542496, 2321386000,
	  1003633490, 1691706554, 3634419848, 3884246949, 1594318824,
	  454302481, 750070978, 4237360308, 824979751, 2158198885,
	  1941074730, 208866433, 2035054943, 1800694593, 1267878658,
	  1400132457, 2486604943, 2203157279, 708323894, 3299919004,
	  582820552, 3579500024, 3187457475, 1214269560, 4284678094,
	  1284918279, 1097613687, 3343042534, 3958893348, 470817812,
	  1568431459, 908604962, 1730635712, 3918326191, 1142113529,
	  345314538, 4120704443, 3485978392, 1059340077, 3225862371,
	  1916498651, 1416647788, 701114700, 4041470005, 142936318,
	  3335243287, 4078039887, 2362477796, 2761139289, 3401108118,
	  1755736123, 3095640141, 941635624, 3858752814, 2912922966,
	  192351108, 3368273949, 2580322815, 1476614381, 426711450,
	  235408906, 2512360830, 1883271248, 4159174448, 1848340175,
	  534912878, 3044652349, 151783695, 1638555956, 1468159766,
	  2671877899, 2637864320, 300552548, 632890829, 2951000029,
	  1167738120, 3752124301, 2744623964, 3934186197, 903492952,
	  3984256464, 1125598204, 4167497931, 4220844977, 933312467,
	  4196268608, 3258827368, 3035673804, 853422685, 2629016689,
	  1443583719, 3815957466, 2275903328, 354161947, 4193253690,
	  1674666943, 877868201, 2587794053, 2978984258, 2083749073,
	  2284226715, 1029651878, 2716639703, 3832997087, 2167046548,
	  2437517569, 260116475, 4001951402, 384702049, 3609319283,
	  2546243573, 2769986984, 4276878911, 1842965941, 2026207406,
	  3308897645, 496573925, 1993176740, 1051541212, 3409038183,
	  3062609479, 4009881435, 303567390, 1612931269, 1792895664,
	  1293897206, 3461271273, 3727548028, 1442403741, 2118680154,
	  558834098, 66192250, 2691014694, 1586388505, 1517836902,
	  1700554059, 1649959502, 4246338885, 109905652, 1088766086,
	  4070109886, 861352876, 392632208, 92210574, 3892701278,
	  1331974013, 2309982570, 274927765, 1958114351, 184420981,
	  1559583890, 2612501364, 758918451, 816132310, 785264201,
	  1240025481, 1181238898, 2000975701, 2833295576, 2521667076,
	  675489981, 2842274089, 3643398521, 2251196049, 3517763975,
	  4095079498, 2371456277, 3601389186, 3104487868, 1117667853,
	  4134467265, 793194424, 3722435846, 590619449, 3426077794,
	  4050317764, 3251618066, 2245821931, 2401406878, 1909027233,
	  2428539120, 2862328403, 25756145, 2345962465, 1324174988,
	  2393607791, 2870127522, 1872916286, 3859670612, 3679640562,
	  2461766267, 3070408630, 1764714954, 967391705, 3554136844,
	  2808194851, 2719916717, 3283403673, 1817209924, 117704453,
	  83231871, 667035462, 2887167143, 3492139126, 1350979603,
	  3696680183, 2220196890, 3775521105, 2059303461, 328274927
	 );

my @m3 =
	 (
	  3644434905, 2417452944, 1906094961, 3534153938, 84345861,
	  2555575704, 1702929253, 3756291807, 138779144, 38507010,
	  2699067552, 1717205094, 3719292125, 2959793584, 3210990015,
	  908736566, 1424362836, 1126221379, 1657550178, 3203569854,
	  504502302, 619444004, 3617713367, 2000776311, 3173532605,
	  851211570, 3564845012, 2609391259, 1879964272, 4181988345,
	  2986054833, 1518225498, 2047079034, 3834433764, 1203145543,
	  1009004604, 2783413413, 1097552961, 115203846, 3311412165,
	  1174214981, 2738510755, 1757560168, 361584917, 569176865,
	  828812849, 1047503422, 374833686, 2500879253, 1542390107,
	  1303937869, 2441490065, 3043875253, 528699679, 1403689811,
	  1667071075, 996714043, 1073670975, 3593512406, 628801061,
	  2813073063, 252251151, 904979253, 598171939, 4036018416,
	  2951318703, 2157787776, 2455565714, 2165076865, 657533991,
	  1993352566, 3881176039, 2073213819, 3922611945, 4043409905,
	  2669570975, 2838778793, 3304155844, 2579739801, 2539385239,
	  2202526083, 1796793963, 3357720008, 244860174, 1847583342,
	  3384014025, 796177967, 3422054091, 4288269567, 3927217642,
	  3981968365, 4158412535, 3784037601, 454368283, 2913083053,
	  215209740, 736295723, 499696413, 425627161, 3257710018,
	  2303322505, 314691346, 2123743102, 545110560, 1678895716,
	  2215344004, 1841641837, 1787408234, 3514577873, 2708588961,
	  3472843470, 935031095, 4212097531, 1035303229, 1373702481,
	  3695095260, 759112749, 2759249316, 2639657373, 4001552622,
	  2252400006, 2927150510, 3441801677, 76958980, 1433879637,
	  168691722, 324044307, 821552944, 3543638483, 1090133312,
	  878815796, 2353982860, 3014657715, 1817473132, 712225322,
	  1379652178, 194986251, 2332195723, 2295898248, 1341329743,
	  1741369703, 1177010758, 3227985856, 3036450996, 674766888,
	  2131031679, 2018009208, 786825006, 122459655, 1264933963,
	  3341529543, 1871620975, 222469645, 3153435835, 4074459890,
	  4081720307, 2789040038, 1503957849, 3166243516, 989458234,
	  4011037167, 4261971454, 26298625, 1628892769, 2094935420,
	  2988527538, 1118932802, 3681696731, 3090106296, 1220511560,
	  749628716, 3821029091, 1463604823, 2241478277, 698968361,
	  2102355069, 2491493012, 1227804233, 398904087, 3395891146,
	  3284008131, 1554224988, 1592264030, 3505224400, 2278665351,
	  2382725006, 3127170490, 2829392552, 3072740279, 3116240569,
	  1619502944, 4174732024, 573974562, 286987281, 3732226014,
	  2044275065, 2867759274, 858602547, 1601784927, 3065447094,
	  2529867926, 1479924312, 2630135964, 4232255484, 444880154,
	  4132249590, 475630108, 951221560, 2889045932, 416270104,
	  4094070260, 1767076969, 1956362100, 4120364277, 1454219094,
	  3672339162, 3588914901, 1257510218, 2660180638, 2729120418,
	  1315067982, 3898542056, 3843922405, 958608441, 3254152897,
	  1147949124, 1563614813, 1917216882, 648045862, 2479733907,
	  64674563, 3334142150, 4204710138, 2195105922, 3480103887,
	  1349533776, 3951418603, 1963654773, 2324902538, 2380244109,
	  1277807180, 337383444, 1943478643, 3434410188, 164942601,
	  277503248, 3796963298, 0, 2585358234, 3759840736, 2408855183,
	  3871818470, 3972614892, 4258422525, 2877276587, 3634946264
	  );

sub __mds_rem;
sub __usage;
sub __padding_error;

use vars qw ($KEYSIZE);

# See method keysize() below for an explanation.
$KEYSIZE = 32;

sub new
{
    __usage (__PACKAGE__ .  "->new (key)")
        unless @_ == 2;

	my ($class, $key) = @_;

	my @key = unpack "C*", $key;
	my $keylength = @key;

	# FIXME: Turn off UTF-8 on the key!
	__padding_error ($keylength)
		unless $keylength == 16 || $keylength == 24 || $keylength == 32;

	# The key consists of k=len/8 (2, 3 or 4) 64-bit units.
	$keylength /= 8;

    my $self = {
		__keylength => $keylength
		};

    # We must derive three vectors Me, Mo, and S, each with k 32-bit
    # words, from the 2k words in the key.
    #
    #       Me = (key[0], key[2], ..., key[2k-2]) (even words)
    #       Mo = (key[1], key[3], ..., key[2k-1]) (odd  words)
    #
    # The third vector is derived by multiplying each of the k groups
    # of 8 bytes from the key by a 4x8 matrix, to get k 32-bit words.
    #
    #       S = (S[k-1], S[k-2], ..., S[0])
    #
    # where S[i] are the 4 bytes from the multiplication, interpreted
    # as a 32-bit word. As described later, mds_rem is equivalent to
    # the matrix multiplication, but faster.
	my @le_longs = unpack "V*", $key;

    # The words of the expanded key K are defined using the h function:
    #
    #       rho     = 2^24 + 2^16 + 2^8 + 2^0 (0x01010101)
    #       A[i]    = h(2i*rho, Me)
    #       B[i]    = ROL(h(2(i+1)*rho, Mo), 8)
    #       K[2i]   = (A[i] + B[i]) mod 2^32
    #       K[2i+1] = ROL((A[i] + 2B[i]) mod 2^32, 9)
    #
    # rho has the property that, for i = 0..255, the word i*rho
    # consists of four equal bytes, each with the value i. The function
    # h is only applied to words of this type, so we only pass it the
    # value of i.
	my @K;

    # The key-dependent S-boxes used in the g() function are created
    # below. They are defined by g(X) = h(X, S), where S is the vector
    # derived from the key. That is, for i=0..3, the S-box S[i] is
    # formed by mapping from x[i] to y[i] in the h function.
    #
    # The relevant lookup tables qN have been precomputed and stored in
    # tables.h; we also perform full key precomputations incorporating
    # the MDS matrix multiplications.
	my (@S0, @S1, @S2, @S3) = @_;
	my ($A, $B, $C);
	my ($i, $j);
	if ($keylength == 2) {
		my ($s7, $s6, $s5, $s4) = __mds_rem ($le_longs[0], $le_longs[1]);
		my ($s3, $s2, $s1, $s0) = __mds_rem ($le_longs[2], $le_longs[3]);

		for ($i = 0, $j = 1; $i < 40; $i += 2, $j += 2) {
			$A = $m0[$q0[$q0[$i] ^ $key[8]] ^ $key[0]] ^
				$m1[$q0[$q1[$i] ^ $key[9]] ^ $key[1]] ^
				$m2[$q1[$q0[$i] ^ $key[10]] ^ $key[2]] ^
				$m3[$q1[$q1[$i] ^ $key[11]]	^ $key[3]];
			$B = $m0[$q0[$q0[$j] ^ $key[12]] ^ $key[4]] ^
				$m1[$q0[$q1[$j] ^ $key[13]] ^ $key[5]] ^
				$m2[$q1[$q0[$j] ^ $key[14]] ^ $key[6]] ^
				$m3[$q1[$q1[$j] ^ $key[15]] ^ $key[7]];

			$B = ($B << 8) | ($B >> 24 & 0xff);
			push @K, $A += $B;
			push @K, (($A += $B) << 9 | $A >> 23 & 0x1ff);
		}
		for (0 .. 255) {
            $S0[$_] = $m0[$q0[$q0[$_] ^ $s4] ^ $s0];
            $S1[$_] = $m1[$q0[$q1[$_] ^ $s5] ^ $s1];
            $S2[$_] = $m2[$q1[$q0[$_] ^ $s6] ^ $s2];
            $S3[$_] = $m3[$q1[$q1[$_] ^ $s7] ^ $s3];
        }
	} elsif ($keylength == 3) {
		my ($sb, $sa, $s9, $s8) = __mds_rem ($le_longs[0], $le_longs[1]);
		my ($s7, $s6, $s5, $s4) = __mds_rem ($le_longs[2], $le_longs[3]);
		my ($s3, $s2, $s1, $s0) = __mds_rem ($le_longs[4], $le_longs[5]);

		for ($i = 0, $j = 1; $i < 40; $i += 2, $j += 2) {
			$A = $m0[$q0[$q0[$q1[$i] ^ $key[16]] ^ $key[8]] ^ $key[0]] ^
				$m1[$q0[$q1[$q1[$i] ^ $key[17]] ^ $key[9]] ^ $key[1]] ^
				$m2[$q1[$q0[$q0[$i] ^ $key[18]] ^ $key[10]] ^ $key[2]] ^
				$m3[$q1[$q1[$q0[$i] ^ $key[19]] ^ $key[11]] ^ $key[3]];
			$B = $m0[$q0[$q0[$q1[$j] ^ $key[20]] ^ $key[12]] ^ $key[4]] ^
				$m1[$q0[$q1[$q1[$j] ^ $key[21]] ^ $key[13]]	^ $key[5]] ^
				$m2[$q1[$q0[$q0[$j] ^ $key[22]] ^ $key[14]]	^ $key[6]] ^
				$m3[$q1[$q1[$q0[$j] ^ $key[23]] ^ $key[15]]	^ $key[7]];
			$B = ($B << 8) | ($B >> 24 & 0xff);
			push @K, $A += $B;
			push @K, (($A += $B) << 9 | $A >> 23 & 0x1ff);
		}
        for (0 .. 255) {
			$S0[$_] = $m0[$q0[$q0[$q1[$_] ^ $s8] ^ $s4] ^ $s0];
            $S1[$_] = $m1[$q0[$q1[$q1[$_] ^ $s9] ^ $s5] ^ $s1];
            $S2[$_] = $m2[$q1[$q0[$q0[$_] ^ $sa] ^ $s6] ^ $s2];
            $S3[$_] = $m3[$q1[$q1[$q0[$_] ^ $sb] ^ $s7] ^ $s3];
        }
	} elsif ($keylength == 4) {
		my ($sf, $se, $sd, $sc) = __mds_rem ($le_longs[0], $le_longs[1]);
		my ($sb, $sa, $s9, $s8) = __mds_rem ($le_longs[2], $le_longs[3]);
		my ($s7, $s6, $s5, $s4) = __mds_rem ($le_longs[4], $le_longs[5]);
		my ($s3, $s2, $s1, $s0) = __mds_rem ($le_longs[6], $le_longs[7]);

		for ($i = 0, $j = 1; $i < 40; $i += 2, $j += 2) {
			$A = $m0[$q0[$q0[$q1[$q1[$i] ^ $key[24]] ^ $key[16]] ^ $key[8]]
					 ^ $key[0]] ^
			    $m1[$q0[$q1[$q1[$q0[$i] ^ $key[25]] ^ $key[17]] ^ $key[9]]
					^ $key[1]] ^
				$m2[$q1[$q0[$q0[$q0[$i] ^ $key[26]] ^ $key[18]] ^ $key[10]]
					^ $key[2]] ^
				$m3[$q1[$q1[$q0[$q1[$i] ^ $key[27]] ^ $key[19]] ^ $key[11]]
					^ $key[3]];
			$B = $m0[$q0[$q0[$q1[$q1[$j] ^ $key[28]] ^ $key[20]] ^ $key[12]]
					 ^ $key[4]] ^
				$m1[$q0[$q1[$q1[$q0[$j] ^ $key[29]] ^ $key[21]] ^ $key[13]]
					^ $key[5]] ^
				$m2[$q1[$q0[$q0[$q0[$j] ^ $key[30]] ^ $key[22]] ^ $key[14]]
					^ $key[6]] ^
				$m3[$q1[$q1[$q0[$q1[$j] ^ $key[31]] ^ $key[23]] ^ $key[15]]
					^ $key[7]];

			$B = ($B << 8) | ($B >> 24 & 0xff);
			push @K, $A += $B;
			push @K, (($A += $B) << 9 | $A >> 23 & 0x1ff);
		}
        for (0 .. 255) {
            $S0[$_] = $m0[$q0[$q0[$q1[$q1[$_]^$sc]^$s8]^$s4]^$s0];
            $S1[$_] = $m1[$q0[$q1[$q1[$q0[$_]^$sd]^$s9]^$s5]^$s1];
            $S2[$_] = $m2[$q1[$q0[$q0[$q0[$_]^$se]^$sa]^$s6]^$s2];
            $S3[$_] = $m3[$q1[$q1[$q0[$q1[$_]^$sf]^$sb]^$s7]^$s3];
        }
	}

	$self->{__K} = \@K;
	$self->{__S} = [ \@S0, \@S1, \@S2, \@S3 ];

	bless $self, $class;
}

sub keysize
{
	my $self = shift;

	if (ref $self) {
		return $self->{__keylength} * 8;
	} else {
		# When called as a class method, return a constant value.
		return $KEYSIZE;
	}
}

sub blocksize
{
	16;
}

sub new_encrypt {
	my ($self, $plain) = @_;

	&{$self->{__encrypt}} ($self, $plain);
}

sub encrypt
{
	my ($self, $cipher) = @_;

	my @words = unpack "V4", $cipher;
	my $K = $self->{__K};

	my $R0 = $K->[0] ^ $words[0];
	my $R1 = $K->[1] ^ $words[1];
	my $R2 = $K->[2] ^ $words[2];
	my $R3 = $K->[3] ^ $words[3];

	my ($t0, $t1);
	my ($S0, $S1, $S2, $S3) = @{$self->{__S}};

	# i = 0
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[($R0 >> 8) & 0xff] ^
		$S2->[($R0 >> 16) & 0xff] ^
		$S3->[($R0 >> 24) & 0xff];
	$t1 = $S0->[($R1 >> 24) & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[($R1 >> 8) & 0xff] ^
		$S3->[($R1 >> 16) & 0xff];

	$R2  ^= ($t0 + $t1 + $K->[8]);
	$R2 = ($R2 >> 1 & 0x7fffffff) | ($R2 << 31);

	$R3 = (($R3 >> 31) & 1) | ($R3 << 1);
	$R3 ^= ($t0 + ($t1 << 1) + $K->[9]);

	$t0 = $S0->[$R2 & 0xff] ^
		$S1->[($R2 >> 8) & 0xff] ^
		$S2->[($R2 >> 16) & 0xff] ^
		$S3->[($R2 >> 24) & 0xff];
	$t1 = $S0->[($R3 >> 24) & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[($R3 >> 8) & 0xff] ^
		$S3->[($R3 >> 16) & 0xff];

	$R0 ^= ($t0 + $t1 + $K->[10]);
	$R0 = ($R0 >> 1 & 0x7fffffff) | ($R0 << 31);

	$R1 = (($R1 >> 31) & 1) | ($R1 << 1);
	$R1 ^= ($t0 + ($t1 << 1) + $K->[11]);

	# i = 1
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[($R0 >> 8) & 0xff] ^
		$S2->[($R0 >> 16) & 0xff] ^
		$S3->[($R0 >> 24) & 0xff];
	$t1 = $S0->[($R1 >> 24) & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[($R1 >> 8) & 0xff] ^
		$S3->[($R1 >> 16) & 0xff];

	$R2  ^= ($t0 + $t1 + $K->[12]);
	$R2 = ($R2 >> 1 & 0x7fffffff) | ($R2 << 31);

	$R3 = (($R3 >> 31) & 1) | ($R3 << 1);
	$R3 ^= ($t0 + ($t1 << 1) + $K->[13]);

	$t0 = $S0->[$R2 & 0xff] ^
		$S1->[($R2 >> 8) & 0xff] ^
		$S2->[($R2 >> 16) & 0xff] ^
		$S3->[($R2 >> 24) & 0xff];
	$t1 = $S0->[($R3 >> 24) & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[($R3 >> 8) & 0xff] ^
		$S3->[($R3 >> 16) & 0xff];

	$R0 ^= ($t0 + $t1 + $K->[14]);
	$R0 = ($R0 >> 1 & 0x7fffffff) | ($R0 << 31);

	$R1 = (($R1 >> 31) & 1) | ($R1 << 1);
	$R1 ^= ($t0 + ($t1 << 1) + $K->[15]);

	# i = 2
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[($R0 >> 8) & 0xff] ^
		$S2->[($R0 >> 16) & 0xff] ^
		$S3->[($R0 >> 24) & 0xff];
	$t1 = $S0->[($R1 >> 24) & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[($R1 >> 8) & 0xff] ^
		$S3->[($R1 >> 16) & 0xff];

	$R2  ^= ($t0 + $t1 + $K->[16]);
	$R2 = ($R2 >> 1 & 0x7fffffff) | ($R2 << 31);

	$R3 = (($R3 >> 31) & 1) | ($R3 << 1);
	$R3 ^= ($t0 + ($t1 << 1) + $K->[17]);

	$t0 = $S0->[$R2 & 0xff] ^
		$S1->[($R2 >> 8) & 0xff] ^
		$S2->[($R2 >> 16) & 0xff] ^
		$S3->[($R2 >> 24) & 0xff];
	$t1 = $S0->[($R3 >> 24) & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[($R3 >> 8) & 0xff] ^
		$S3->[($R3 >> 16) & 0xff];

	$R0 ^= ($t0 + $t1 + $K->[18]);
	$R0 = ($R0 >> 1 & 0x7fffffff) | ($R0 << 31);

	$R1 = (($R1 >> 31) & 1) | ($R1 << 1);
	$R1 ^= ($t0 + ($t1 << 1) + $K->[19]);

	# i = 3
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[($R0 >> 8) & 0xff] ^
		$S2->[($R0 >> 16) & 0xff] ^
		$S3->[($R0 >> 24) & 0xff];
	$t1 = $S0->[($R1 >> 24) & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[($R1 >> 8) & 0xff] ^
		$S3->[($R1 >> 16) & 0xff];

	$R2  ^= ($t0 + $t1 + $K->[20]);
	$R2 = ($R2 >> 1 & 0x7fffffff) | ($R2 << 31);

	$R3 = (($R3 >> 31) & 1) | ($R3 << 1);
	$R3 ^= ($t0 + ($t1 << 1) + $K->[21]);

	$t0 = $S0->[$R2 & 0xff] ^
		$S1->[($R2 >> 8) & 0xff] ^
		$S2->[($R2 >> 16) & 0xff] ^
		$S3->[($R2 >> 24) & 0xff];
	$t1 = $S0->[($R3 >> 24) & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[($R3 >> 8) & 0xff] ^
		$S3->[($R3 >> 16) & 0xff];

	$R0 ^= ($t0 + $t1 + $K->[22]);
	$R0 = ($R0 >> 1 & 0x7fffffff) | ($R0 << 31);

	$R1 = (($R1 >> 31) & 1) | ($R1 << 1);
	$R1 ^= ($t0 + ($t1 << 1) + $K->[23]);

	# i = 4
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[($R0 >> 8) & 0xff] ^
		$S2->[($R0 >> 16) & 0xff] ^
		$S3->[($R0 >> 24) & 0xff];
	$t1 = $S0->[($R1 >> 24) & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[($R1 >> 8) & 0xff] ^
		$S3->[($R1 >> 16) & 0xff];

	$R2  ^= ($t0 + $t1 + $K->[24]);
	$R2 = ($R2 >> 1 & 0x7fffffff) | ($R2 << 31);

	$R3 = (($R3 >> 31) & 1) | ($R3 << 1);
	$R3 ^= ($t0 + ($t1 << 1) + $K->[25]);

	$t0 = $S0->[$R2 & 0xff] ^
		$S1->[($R2 >> 8) & 0xff] ^
		$S2->[($R2 >> 16) & 0xff] ^
		$S3->[($R2 >> 24) & 0xff];
	$t1 = $S0->[($R3 >> 24) & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[($R3 >> 8) & 0xff] ^
		$S3->[($R3 >> 16) & 0xff];

	$R0 ^= ($t0 + $t1 + $K->[26]);
	$R0 = ($R0 >> 1 & 0x7fffffff) | ($R0 << 31);

	$R1 = (($R1 >> 31) & 1) | ($R1 << 1);
	$R1 ^= ($t0 + ($t1 << 1) + $K->[27]);

	# i = 5
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[($R0 >> 8) & 0xff] ^
		$S2->[($R0 >> 16) & 0xff] ^
		$S3->[($R0 >> 24) & 0xff];
	$t1 = $S0->[($R1 >> 24) & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[($R1 >> 8) & 0xff] ^
		$S3->[($R1 >> 16) & 0xff];

	$R2  ^= ($t0 + $t1 + $K->[28]);
	$R2 = ($R2 >> 1 & 0x7fffffff) | ($R2 << 31);

	$R3 = (($R3 >> 31) & 1) | ($R3 << 1);
	$R3 ^= ($t0 + ($t1 << 1) + $K->[29]);

	$t0 = $S0->[$R2 & 0xff] ^
		$S1->[($R2 >> 8) & 0xff] ^
		$S2->[($R2 >> 16) & 0xff] ^
		$S3->[($R2 >> 24) & 0xff];
	$t1 = $S0->[($R3 >> 24) & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[($R3 >> 8) & 0xff] ^
		$S3->[($R3 >> 16) & 0xff];

	$R0 ^= ($t0 + $t1 + $K->[30]);
	$R0 = ($R0 >> 1 & 0x7fffffff) | ($R0 << 31);

	$R1 = (($R1 >> 31) & 1) | ($R1 << 1);
	$R1 ^= ($t0 + ($t1 << 1) + $K->[31]);

	# i = 6
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[($R0 >> 8) & 0xff] ^
		$S2->[($R0 >> 16) & 0xff] ^
		$S3->[($R0 >> 24) & 0xff];
	$t1 = $S0->[($R1 >> 24) & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[($R1 >> 8) & 0xff] ^
		$S3->[($R1 >> 16) & 0xff];

	$R2  ^= ($t0 + $t1 + $K->[32]);
	$R2 = ($R2 >> 1 & 0x7fffffff) | ($R2 << 31);

	$R3 = (($R3 >> 31) & 1) | ($R3 << 1);
	$R3 ^= ($t0 + ($t1 << 1) + $K->[33]);

	$t0 = $S0->[$R2 & 0xff] ^
		$S1->[($R2 >> 8) & 0xff] ^
		$S2->[($R2 >> 16) & 0xff] ^
		$S3->[($R2 >> 24) & 0xff];
	$t1 = $S0->[($R3 >> 24) & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[($R3 >> 8) & 0xff] ^
		$S3->[($R3 >> 16) & 0xff];

	$R0 ^= ($t0 + $t1 + $K->[34]);
	$R0 = ($R0 >> 1 & 0x7fffffff) | ($R0 << 31);

	$R1 = (($R1 >> 31) & 1) | ($R1 << 1);
	$R1 ^= ($t0 + ($t1 << 1) + $K->[35]);

	# i = 7
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[($R0 >> 8) & 0xff] ^
		$S2->[($R0 >> 16) & 0xff] ^
		$S3->[($R0 >> 24) & 0xff];
	$t1 = $S0->[($R1 >> 24) & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[($R1 >> 8) & 0xff] ^
		$S3->[($R1 >> 16) & 0xff];

	$R2  ^= ($t0 + $t1 + $K->[36]);
	$R2 = ($R2 >> 1 & 0x7fffffff) | ($R2 << 31);

	$R3 = (($R3 >> 31) & 1) | ($R3 << 1);
	$R3 ^= ($t0 + ($t1 << 1) + $K->[37]);

	$t0 = $S0->[$R2 & 0xff] ^
		$S1->[($R2 >> 8) & 0xff] ^
		$S2->[($R2 >> 16) & 0xff] ^
		$S3->[($R2 >> 24) & 0xff];
	$t1 = $S0->[($R3 >> 24) & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[($R3 >> 8) & 0xff] ^
		$S3->[($R3 >> 16) & 0xff];

	$R0 ^= ($t0 + $t1 + $K->[38]);
	$R0 = ($R0 >> 1 & 0x7fffffff) | ($R0 << 31);

	$R1 = (($R1 >> 31) & 1) | ($R1 << 1);
	$R1 ^= ($t0 + ($t1 << 1) + $K->[39]);

	return pack "V4", ($K->[4] ^ $R2,
					   $K->[5] ^ $R3,
					   $K->[6] ^ $R0,
					   $K->[7] ^ $R1);
}

sub decrypt
{
	my ($self, $plain) = @_;
	my @words = unpack "V4", $plain;
	my $K = $self->{__K};
	my $S = $self->{__S};

	my $R0 = $K->[4] ^ $words[0];
	my $R1 = $K->[5] ^ $words[1];
	my $R2 = $K->[6] ^ $words[2];
	my $R3 = $K->[7] ^ $words[3];

	my ($t0, $t1);
	my ($S0, $S1, $S2, $S3) = @{$self->{__S}};

	# i = 7
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[$R0 >> 8 & 0xff] ^
		$S2->[$R0 >> 16 & 0xff] ^
		$S3->[$R0 >> 24 & 0xff];
	$t1 = $S0->[$R1 >> 24 & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[$R1 >> 8 & 0xff] ^
		$S3->[$R1 >> 16 & 0xff];

	$R2 = $R2 >> 31 & 0x1 | $R2 << 1;
	$R2 ^= $t0 + $t1 + $K->[38];

	$R3 ^= $t0 + ($t1 << 1) + $K->[39];
	$R3 = $R3 >> 1 & 0x7fffffff | $R3 << 31;

	$t0 = $S0->[$R2 & 0xff] ^
			$S1->[$R2 >> 8 & 0xff] ^
			$S2->[$R2 >> 16 & 0xff] ^
			$S3->[$R2 >> 24 & 0xff];
	$t1 = $S0->[$R3 >> 24 & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[$R3 >> 8 & 0xff] ^
		$S3->[$R3 >> 16 & 0xff];

	$R0 = $R0 >> 31 & 0x1 | $R0 << 1;
	$R0 ^= $t0 + $t1 + $K->[36];

	$R1 ^= $t0 + ($t1 << 1) + $K->[37];
	$R1 = $R1 >> 1 & 0x7fffffff | $R1 << 31;

	# i = 6
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[$R0 >> 8 & 0xff] ^
		$S2->[$R0 >> 16 & 0xff] ^
		$S3->[$R0 >> 24 & 0xff];
	$t1 = $S0->[$R1 >> 24 & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[$R1 >> 8 & 0xff] ^
		$S3->[$R1 >> 16 & 0xff];

	$R2 = $R2 >> 31 & 0x1 | $R2 << 1;
	$R2 ^= $t0 + $t1 + $K->[34];

	$R3 ^= $t0 + ($t1 << 1) + $K->[35];
	$R3 = $R3 >> 1 & 0x7fffffff | $R3 << 31;

	$t0 = $S0->[$R2 & 0xff] ^
		$S1->[$R2 >> 8 & 0xff] ^
		$S2->[$R2 >> 16 & 0xff] ^
		$S3->[$R2 >> 24 & 0xff];
	$t1 = $S0->[$R3 >> 24 & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[$R3 >> 8 & 0xff] ^
		$S3->[$R3 >> 16 & 0xff];

	$R0 = $R0 >> 31 & 0x1 | $R0 << 1;
	$R0 ^= $t0 + $t1 + $K->[32];

	$R1 ^= $t0 + ($t1 << 1) + $K->[33];
	$R1 = $R1 >> 1 & 0x7fffffff | $R1 << 31;

	# i = 5
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[$R0 >> 8 & 0xff] ^
		$S2->[$R0 >> 16 & 0xff] ^
		$S3->[$R0 >> 24 & 0xff];
	$t1 = $S0->[$R1 >> 24 & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[$R1 >> 8 & 0xff] ^
		$S3->[$R1 >> 16 & 0xff];

	$R2 = $R2 >> 31 & 0x1 | $R2 << 1;
	$R2 ^= $t0 + $t1 + $K->[30];

	$R3 ^= $t0 + ($t1 << 1) + $K->[31];
	$R3 = $R3 >> 1 & 0x7fffffff | $R3 << 31;

	$t0 = $S0->[$R2 & 0xff] ^
		$S1->[$R2 >> 8 & 0xff] ^
		$S2->[$R2 >> 16 & 0xff] ^
		$S3->[$R2 >> 24 & 0xff];
	$t1 = $S0->[$R3 >> 24 & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[$R3 >> 8 & 0xff] ^
		$S3->[$R3 >> 16 & 0xff];

	$R0 = $R0 >> 31 & 0x1 | $R0 << 1;
	$R0 ^= $t0 + $t1 + $K->[28];

	$R1 ^= $t0 + ($t1 << 1) + $K->[29];
	$R1 = $R1 >> 1 & 0x7fffffff | $R1 << 31;

	# i = 4
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[$R0 >> 8 & 0xff] ^
		$S2->[$R0 >> 16 & 0xff] ^
		$S3->[$R0 >> 24 & 0xff];
	$t1 = $S0->[$R1 >> 24 & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[$R1 >> 8 & 0xff] ^
		$S3->[$R1 >> 16 & 0xff];

	$R2 = $R2 >> 31 & 0x1 | $R2 << 1;
	$R2 ^= $t0 + $t1 + $K->[26];

	$R3 ^= $t0 + ($t1 << 1) + $K->[27];
	$R3 = $R3 >> 1 & 0x7fffffff | $R3 << 31;

	$t0 = $S0->[$R2 & 0xff] ^
		$S1->[$R2 >> 8 & 0xff] ^
		$S2->[$R2 >> 16 & 0xff] ^
		$S3->[$R2 >> 24 & 0xff];
	$t1 = $S0->[$R3 >> 24 & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[$R3 >> 8 & 0xff] ^
		$S3->[$R3 >> 16 & 0xff];

	$R0 = $R0 >> 31 & 0x1 | $R0 << 1;
	$R0 ^= $t0 + $t1 + $K->[24];

	$R1 ^= $t0 + ($t1 << 1) + $K->[25];
	$R1 = $R1 >> 1 & 0x7fffffff | $R1 << 31;

	# i = 3
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[$R0 >> 8 & 0xff] ^
		$S2->[$R0 >> 16 & 0xff] ^
		$S3->[$R0 >> 24 & 0xff];
	$t1 = $S0->[$R1 >> 24 & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[$R1 >> 8 & 0xff] ^
		$S3->[$R1 >> 16 & 0xff];

	$R2 = $R2 >> 31 & 0x1 | $R2 << 1;
	$R2 ^= $t0 + $t1 + $K->[22];

	$R3 ^= $t0 + ($t1 << 1) + $K->[23];
	$R3 = $R3 >> 1 & 0x7fffffff | $R3 << 31;

	$t0 = $S0->[$R2 & 0xff] ^
		$S1->[$R2 >> 8 & 0xff] ^
		$S2->[$R2 >> 16 & 0xff] ^
		$S3->[$R2 >> 24 & 0xff];
	$t1 = $S0->[$R3 >> 24 & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[$R3 >> 8 & 0xff] ^
		$S3->[$R3 >> 16 & 0xff];

	$R0 = $R0 >> 31 & 0x1 | $R0 << 1;
	$R0 ^= $t0 + $t1 + $K->[20];

	$R1 ^= $t0 + ($t1 << 1) + $K->[21];
	$R1 = $R1 >> 1 & 0x7fffffff | $R1 << 31;

	# i = 2
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[$R0 >> 8 & 0xff] ^
		$S2->[$R0 >> 16 & 0xff] ^
		$S3->[$R0 >> 24 & 0xff];
	$t1 = $S0->[$R1 >> 24 & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[$R1 >> 8 & 0xff] ^
		$S3->[$R1 >> 16 & 0xff];

	$R2 = $R2 >> 31 & 0x1 | $R2 << 1;
	$R2 ^= $t0 + $t1 + $K->[18];

	$R3 ^= $t0 + ($t1 << 1) + $K->[19];
	$R3 = $R3 >> 1 & 0x7fffffff | $R3 << 31;

	$t0 = $S0->[$R2 & 0xff] ^
		$S1->[$R2 >> 8 & 0xff] ^
		$S2->[$R2 >> 16 & 0xff] ^
		$S3->[$R2 >> 24 & 0xff];
	$t1 = $S0->[$R3 >> 24 & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[$R3 >> 8 & 0xff] ^
		$S3->[$R3 >> 16 & 0xff];

	$R0 = $R0 >> 31 & 0x1 | $R0 << 1;
	$R0 ^= $t0 + $t1 + $K->[16];

	$R1 ^= $t0 + ($t1 << 1) + $K->[17];
	$R1 = $R1 >> 1 & 0x7fffffff | $R1 << 31;

	# i = 1
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[$R0 >> 8 & 0xff] ^
		$S2->[$R0 >> 16 & 0xff] ^
		$S3->[$R0 >> 24 & 0xff];
	$t1 = $S0->[$R1 >> 24 & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[$R1 >> 8 & 0xff] ^
		$S3->[$R1 >> 16 & 0xff];

	$R2 = $R2 >> 31 & 0x1 | $R2 << 1;
	$R2 ^= $t0 + $t1 + $K->[14];

	$R3 ^= $t0 + ($t1 << 1) + $K->[15];
	$R3 = $R3 >> 1 & 0x7fffffff | $R3 << 31;

	$t0 = $S0->[$R2 & 0xff] ^
		$S1->[$R2 >> 8 & 0xff] ^
		$S2->[$R2 >> 16 & 0xff] ^
		$S3->[$R2 >> 24 & 0xff];
	$t1 = $S0->[$R3 >> 24 & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[$R3 >> 8 & 0xff] ^
		$S3->[$R3 >> 16 & 0xff];

	$R0 = $R0 >> 31 & 0x1 | $R0 << 1;
	$R0 ^= $t0 + $t1 + $K->[12];

	$R1 ^= $t0 + ($t1 << 1) + $K->[13];
	$R1 = $R1 >> 1 & 0x7fffffff | $R1 << 31;

	# i = 0
	$t0 = $S0->[$R0 & 0xff] ^
		$S1->[$R0 >> 8 & 0xff] ^
		$S2->[$R0 >> 16 & 0xff] ^
		$S3->[$R0 >> 24 & 0xff];
	$t1 = $S0->[$R1 >> 24 & 0xff] ^
		$S1->[$R1 & 0xff] ^
		$S2->[$R1 >> 8 & 0xff] ^
		$S3->[$R1 >> 16 & 0xff];

	$R2 = $R2 >> 31 & 0x1 | $R2 << 1;
	$R2 ^= $t0 + $t1 + $K->[10];

	$R3 ^= $t0 + ($t1 << 1) + $K->[11];
	$R3 = $R3 >> 1 & 0x7fffffff | $R3 << 31;

	$t0 = $S0->[$R2 & 0xff] ^
		$S1->[$R2 >> 8 & 0xff] ^
		$S2->[$R2 >> 16 & 0xff] ^
		$S3->[$R2 >> 24 & 0xff];
	$t1 = $S0->[$R3 >> 24 & 0xff] ^
		$S1->[$R3 & 0xff] ^
		$S2->[$R3 >> 8 & 0xff] ^
		$S3->[$R3 >> 16 & 0xff];

	$R0 = $R0 >> 31 & 0x1 | $R0 << 1;
	$R0 ^= $t0 + $t1 + $K->[8];

	$R1 ^= $t0 + ($t1 << 1) + $K->[9];
	$R1 = $R1 >> 1 & 0x7fffffff | $R1 << 31;

	return pack "V4", ($K->[0] ^ $R2,
					   $K->[1] ^ $R3,
					   $K->[2] ^ $R0,
					   $K->[3] ^ $R1);
}

sub __usage
{
	my $msg = shift;

    my ($package, $filename, $line, $subr) = caller (1);
	require Carp;
    $Carp::CarpLevel = 2;
    Carp::croak (__"Usage:", " $msg");
}

sub __padding_error
{
	my $keylength = shift;

	require Carp;
    $Carp::CarpLevel = 2;
    Carp::croak (__x ("wrong key length {keylength}: "
					  . "key must be 16, 24 or 32 bytes long",
					  $keylength));
}

# The (12, 8) Reed Solomon code has the generator polynomial:
#
#      g(x) = x^4 + (a + 1/a) * x^3 + a * x^2 + (a + 1/a) * x + 1
#
#   where the coefficients are in the finite field GF(2^8) with a modular
#   polynomial a^8+a^6+a^3+a^2+1. To generate the remainder, we have to
#   start with a 12th order polynomial with our eight input bytes as the
#   coefficients of the 4th to 11th terms:
#
#        m[7] * x^11 + m[6] * x^10 ... + m[0] * x^4 + 0 * x^3 +... + 0
#
#   We then multiply the generator polynomial by m[7]*x^7 and subtract it
#   (XOR in GF(2^8)) from the above to eliminate the x^7 term (the
#   arithmetic on the coefficients is done in GF(2^8)). We then multiply
#   the generator polynomial by m[6]*x^6 and use this to remove the x^10
#   term, and so on until the x^4 term is removed, and we are left with:
#
#        r[3] * x^3 + r[2] * x^2 + r[1] 8 x^1 + r[0]
#
#   which give the resulting 4 bytes of the remainder. This is equivalent
#   to the matrix multiplication described in the Twofish paper, but is
#   much faster.
sub __mds_rem
{
	my ($A, $B) = @_;

	# use constant G_MOD => 0x14d;

	# No gain by unrolling this loop.
	my ($t, $u);
	foreach (0 .. 7) {
        # Get most significant coefficient.
        $t = 0xff & ($B >> 24);

        # Shift the others up.
        $B = ($B << 8) | (0xff & ($A >> 24));
        $A <<= 8;

        $u = $t << 1;

        # Subtract the modular polynomial on overflow.
		$u ^= 0x14d if $t & 0x80;

        # Remove t * (a * x^2 + 1).
        $B ^= $t ^ ($u << 16);

        # Form u = a*t + t/a = t*(a + 1/a).
        $u ^= 0x7fffffff & ($t >> 1);

        # Add the modular polynomial on underflow.
		$u ^= 0xa6 if $t & 0x01;

		# Remove t * (a + 1/a) * (x^3 + x).
        $B ^= ($u << 24) | ($u << 8);
	}

	return map 0xff & $_, $B >> 24, $B >> 16, $B >> 8, $B;
}

1;

__END__