strongSwan

/* NOTE: This implementation has been changed from the original

 * source. See ChangeLog for more information.

 * Maintained by Marc Mutz <Marc@Mutz.com>

 */

/* Twofish for GPG

 * By Matthew Skala <mskala@ansuz.sooke.bc.ca>, July 26, 1998

 * 256-bit key length added March 20, 1999

 * Some modifications to reduce the text size by Werner Koch, April, 1998

 *

 * The original author has disclaimed all copyright interest in this

 * code and thus putting it in the public domain.

 *

 * This code is a "clean room" implementation, written from the paper

 * _Twofish: A 128-Bit Block Cipher_ by Bruce Schneier, John Kelsey,

 * Doug Whiting, David Wagner, Chris Hall, and Niels Ferguson, available

 * through http://www.counterpane.com/twofish.html

 *

 * For background information on multiplication in finite fields, used for

 * the matrix operations in the key schedule, see the book _Contemporary

 * Abstract Algebra_ by Joseph A. Gallian, especially chapter 22 in the

 * Third Edition.

 *

 * Only the 128- and 256-bit key sizes are supported.  This code is intended

 * for GNU C on a 32-bit system, but it should work almost anywhere.  Loops

 * are unrolled, precomputation tables are used, etc., for maximum speed at

 * some cost in memory consumption. */

#ifdef __KERNEL__

#include <linux/init.h>

#include <linux/types.h>

#else

#include <sys/types.h>

#define u8 u_int8_t

#define u32 u_int32_t

#endif

#if 0 /* shouldn't this be #ifdef rotl32 ?

       * Look at wordops.h: It includes asm/wordops.h.

       * Anyway, we have to search in the macros for rot's,

       * since they seem to be defined in a generic way. */

#define rotl rotl32

#define rotr rotr32

#else

#define rotl generic_rotl32

#define rotr generic_rotr32

#endif

#include "twofish.h"

/* The large precomputed tables for the Twofish cipher (twofish.c)

 * Taken from the same source as twofish.c

 * Marc Mutz <Marc@Mutz.com>

 */

/* These two tables are the q0 and q1 permutations, exactly as described in

 * the Twofish paper. */

static const u8 q0[256] = {

   0xA9, 0x67, 0xB3, 0xE8, 0x04, 0xFD, 0xA3, 0x76, 0x9A, 0x92, 0x80, 0x78,

   0xE4, 0xDD, 0xD1, 0x38, 0x0D, 0xC6, 0x35, 0x98, 0x18, 0xF7, 0xEC, 0x6C,

   0x43, 0x75, 0x37, 0x26, 0xFA, 0x13, 0x94, 0x48, 0xF2, 0xD0, 0x8B, 0x30,

   0x84, 0x54, 0xDF, 0x23, 0x19, 0x5B, 0x3D, 0x59, 0xF3, 0xAE, 0xA2, 0x82,

   0x63, 0x01, 0x83, 0x2E, 0xD9, 0x51, 0x9B, 0x7C, 0xA6, 0xEB, 0xA5, 0xBE,

   0x16, 0x0C, 0xE3, 0x61, 0xC0, 0x8C, 0x3A, 0xF5, 0x73, 0x2C, 0x25, 0x0B,

   0xBB, 0x4E, 0x89, 0x6B, 0x53, 0x6A, 0xB4, 0xF1, 0xE1, 0xE6, 0xBD, 0x45,

   0xE2, 0xF4, 0xB6, 0x66, 0xCC, 0x95, 0x03, 0x56, 0xD4, 0x1C, 0x1E, 0xD7,

   0xFB, 0xC3, 0x8E, 0xB5, 0xE9, 0xCF, 0xBF, 0xBA, 0xEA, 0x77, 0x39, 0xAF,

   0x33, 0xC9, 0x62, 0x71, 0x81, 0x79, 0x09, 0xAD, 0x24, 0xCD, 0xF9, 0xD8,

   0xE5, 0xC5, 0xB9, 0x4D, 0x44, 0x08, 0x86, 0xE7, 0xA1, 0x1D, 0xAA, 0xED,

   0x06, 0x70, 0xB2, 0xD2, 0x41, 0x7B, 0xA0, 0x11, 0x31, 0xC2, 0x27, 0x90,

   0x20, 0xF6, 0x60, 0xFF, 0x96, 0x5C, 0xB1, 0xAB, 0x9E, 0x9C, 0x52, 0x1B,

   0x5F, 0x93, 0x0A, 0xEF, 0x91, 0x85, 0x49, 0xEE, 0x2D, 0x4F, 0x8F, 0x3B,

   0x47, 0x87, 0x6D, 0x46, 0xD6, 0x3E, 0x69, 0x64, 0x2A, 0xCE, 0xCB, 0x2F,

   0xFC, 0x97, 0x05, 0x7A, 0xAC, 0x7F, 0xD5, 0x1A, 0x4B, 0x0E, 0xA7, 0x5A,

   0x28, 0x14, 0x3F, 0x29, 0x88, 0x3C, 0x4C, 0x02, 0xB8, 0xDA, 0xB0, 0x17,

   0x55, 0x1F, 0x8A, 0x7D, 0x57, 0xC7, 0x8D, 0x74, 0xB7, 0xC4, 0x9F, 0x72,

   0x7E, 0x15, 0x22, 0x12, 0x58, 0x07, 0x99, 0x34, 0x6E, 0x50, 0xDE, 0x68,

   0x65, 0xBC, 0xDB, 0xF8, 0xC8, 0xA8, 0x2B, 0x40, 0xDC, 0xFE, 0x32, 0xA4,

   0xCA, 0x10, 0x21, 0xF0, 0xD3, 0x5D, 0x0F, 0x00, 0x6F, 0x9D, 0x36, 0x42,

   0x4A, 0x5E, 0xC1, 0xE0

};

static const u8 q1[256] = {

   0x75, 0xF3, 0xC6, 0xF4, 0xDB, 0x7B, 0xFB, 0xC8, 0x4A, 0xD3, 0xE6, 0x6B,

   0x45, 0x7D, 0xE8, 0x4B, 0xD6, 0x32, 0xD8, 0xFD, 0x37, 0x71, 0xF1, 0xE1,

   0x30, 0x0F, 0xF8, 0x1B, 0x87, 0xFA, 0x06, 0x3F, 0x5E, 0xBA, 0xAE, 0x5B,

   0x8A, 0x00, 0xBC, 0x9D, 0x6D, 0xC1, 0xB1, 0x0E, 0x80, 0x5D, 0xD2, 0xD5,

   0xA0, 0x84, 0x07, 0x14, 0xB5, 0x90, 0x2C, 0xA3, 0xB2, 0x73, 0x4C, 0x54,

   0x92, 0x74, 0x36, 0x51, 0x38, 0xB0, 0xBD, 0x5A, 0xFC, 0x60, 0x62, 0x96,

   0x6C, 0x42, 0xF7, 0x10, 0x7C, 0x28, 0x27, 0x8C, 0x13, 0x95, 0x9C, 0xC7,

   0x24, 0x46, 0x3B, 0x70, 0xCA, 0xE3, 0x85, 0xCB, 0x11, 0xD0, 0x93, 0xB8,

   0xA6, 0x83, 0x20, 0xFF, 0x9F, 0x77, 0xC3, 0xCC, 0x03, 0x6F, 0x08, 0xBF,

   0x40, 0xE7, 0x2B, 0xE2, 0x79, 0x0C, 0xAA, 0x82, 0x41, 0x3A, 0xEA, 0xB9,

   0xE4, 0x9A, 0xA4, 0x97, 0x7E, 0xDA, 0x7A, 0x17, 0x66, 0x94, 0xA1, 0x1D,

   0x3D, 0xF0, 0xDE, 0xB3, 0x0B, 0x72, 0xA7, 0x1C, 0xEF, 0xD1, 0x53, 0x3E,

   0x8F, 0x33, 0x26, 0x5F, 0xEC, 0x76, 0x2A, 0x49, 0x81, 0x88, 0xEE, 0x21,

   0xC4, 0x1A, 0xEB, 0xD9, 0xC5, 0x39, 0x99, 0xCD, 0xAD, 0x31, 0x8B, 0x01,

   0x18, 0x23, 0xDD, 0x1F, 0x4E, 0x2D, 0xF9, 0x48, 0x4F, 0xF2, 0x65, 0x8E,

   0x78, 0x5C, 0x58, 0x19, 0x8D, 0xE5, 0x98, 0x57, 0x67, 0x7F, 0x05, 0x64,

   0xAF, 0x63, 0xB6, 0xFE, 0xF5, 0xB7, 0x3C, 0xA5, 0xCE, 0xE9, 0x68, 0x44,

   0xE0, 0x4D, 0x43, 0x69, 0x29, 0x2E, 0xAC, 0x15, 0x59, 0xA8, 0x0A, 0x9E,

   0x6E, 0x47, 0xDF, 0x34, 0x35, 0x6A, 0xCF, 0xDC, 0x22, 0xC9, 0xC0, 0x9B,

   0x89, 0xD4, 0xED, 0xAB, 0x12, 0xA2, 0x0D, 0x52, 0xBB, 0x02, 0x2F, 0xA9,

   0xD7, 0x61, 0x1E, 0xB4, 0x50, 0x04, 0xF6, 0xC2, 0x16, 0x25, 0x86, 0x56,

   0x55, 0x09, 0xBE, 0x91

};

/* These MDS tables are actually tables of MDS composed with q0 and q1,

 * because it is only ever used that way and we can save some time by

 * precomputing.  Of course the main saving comes from precomputing the

 * GF(2^8) multiplication involved in the MDS matrix multiply; by looking

 * things up in these tables we reduce the matrix multiply to four lookups

 * and three XORs.  Semi-formally, the definition of these tables is:

 * mds[0][i] = MDS (q1[i] 0 0 0)^T  mds[1][i] = MDS (0 q0[i] 0 0)^T

 * mds[2][i] = MDS (0 0 q1[i] 0)^T  mds[3][i] = MDS (0 0 0 q0[i])^T

 * where ^T means "transpose", the matrix multiply is performed in GF(2^8)

 * represented as GF(2)[x]/v(x) where v(x)=x^8+x^6+x^5+x^3+1 as described

 * by Schneier et al, and I'm casually glossing over the byte/word

 * conversion issues. */

static const u32 mds[4][256] = {

   {0xBCBC3275, 0xECEC21F3, 0x202043C6, 0xB3B3C9F4, 0xDADA03DB, 0x02028B7B,

    0xE2E22BFB, 0x9E9EFAC8, 0xC9C9EC4A, 0xD4D409D3, 0x18186BE6, 0x1E1E9F6B,

    0x98980E45, 0xB2B2387D, 0xA6A6D2E8, 0x2626B74B, 0x3C3C57D6, 0x93938A32,

    0x8282EED8, 0x525298FD, 0x7B7BD437, 0xBBBB3771, 0x5B5B97F1, 0x474783E1,

    0x24243C30, 0x5151E20F, 0xBABAC6F8, 0x4A4AF31B, 0xBFBF4887, 0x0D0D70FA,

    0xB0B0B306, 0x7575DE3F, 0xD2D2FD5E, 0x7D7D20BA, 0x666631AE, 0x3A3AA35B,

    0x59591C8A, 0x00000000, 0xCDCD93BC, 0x1A1AE09D, 0xAEAE2C6D, 0x7F7FABC1,

    0x2B2BC7B1, 0xBEBEB90E, 0xE0E0A080, 0x8A8A105D, 0x3B3B52D2, 0x6464BAD5,

    0xD8D888A0, 0xE7E7A584, 0x5F5FE807, 0x1B1B1114, 0x2C2CC2B5, 0xFCFCB490,

    0x3131272C, 0x808065A3, 0x73732AB2, 0x0C0C8173, 0x79795F4C, 0x6B6B4154,

    0x4B4B0292, 0x53536974, 0x94948F36, 0x83831F51, 0x2A2A3638, 0xC4C49CB0,

    0x2222C8BD, 0xD5D5F85A, 0xBDBDC3FC, 0x48487860, 0xFFFFCE62, 0x4C4C0796,

    0x4141776C, 0xC7C7E642, 0xEBEB24F7, 0x1C1C1410, 0x5D5D637C, 0x36362228,

    0x6767C027, 0xE9E9AF8C, 0x4444F913, 0x1414EA95, 0xF5F5BB9C, 0xCFCF18C7,

    0x3F3F2D24, 0xC0C0E346, 0x7272DB3B, 0x54546C70, 0x29294CCA, 0xF0F035E3,

    0x0808FE85, 0xC6C617CB, 0xF3F34F11, 0x8C8CE4D0, 0xA4A45993, 0xCACA96B8,

    0x68683BA6, 0xB8B84D83, 0x38382820, 0xE5E52EFF, 0xADAD569F, 0x0B0B8477,

    0xC8C81DC3, 0x9999FFCC, 0x5858ED03, 0x19199A6F, 0x0E0E0A08, 0x95957EBF,

    0x70705040, 0xF7F730E7, 0x6E6ECF2B, 0x1F1F6EE2, 0xB5B53D79, 0x09090F0C,

    0x616134AA, 0x57571682, 0x9F9F0B41, 0x9D9D803A, 0x111164EA, 0x2525CDB9,

    0xAFAFDDE4, 0x4545089A, 0xDFDF8DA4, 0xA3A35C97, 0xEAEAD57E, 0x353558DA,

    0xEDEDD07A, 0x4343FC17, 0xF8F8CB66, 0xFBFBB194, 0x3737D3A1, 0xFAFA401D,

    0xC2C2683D, 0xB4B4CCF0, 0x32325DDE, 0x9C9C71B3, 0x5656E70B, 0xE3E3DA72,

    0x878760A7, 0x15151B1C, 0xF9F93AEF, 0x6363BFD1, 0x3434A953, 0x9A9A853E,

    0xB1B1428F, 0x7C7CD133, 0x88889B26, 0x3D3DA65F, 0xA1A1D7EC, 0xE4E4DF76,

    0x8181942A, 0x91910149, 0x0F0FFB81, 0xEEEEAA88, 0x161661EE, 0xD7D77321,

    0x9797F5C4, 0xA5A5A81A, 0xFEFE3FEB, 0x6D6DB5D9, 0x7878AEC5, 0xC5C56D39,

    0x1D1DE599, 0x7676A4CD, 0x3E3EDCAD, 0xCBCB6731, 0xB6B6478B, 0xEFEF5B01,

    0x12121E18, 0x6060C523, 0x6A6AB0DD, 0x4D4DF61F, 0xCECEE94E, 0xDEDE7C2D,

    0x55559DF9, 0x7E7E5A48, 0x2121B24F, 0x03037AF2, 0xA0A02665, 0x5E5E198E,

    0x5A5A6678, 0x65654B5C, 0x62624E58, 0xFDFD4519, 0x0606F48D, 0x404086E5,

    0xF2F2BE98, 0x3333AC57, 0x17179067, 0x05058E7F, 0xE8E85E05, 0x4F4F7D64,

    0x89896AAF, 0x10109563, 0x74742FB6, 0x0A0A75FE, 0x5C5C92F5, 0x9B9B74B7,

    0x2D2D333C, 0x3030D6A5, 0x2E2E49CE, 0x494989E9, 0x46467268, 0x77775544,

    0xA8A8D8E0, 0x9696044D, 0x2828BD43, 0xA9A92969, 0xD9D97929, 0x8686912E,

    0xD1D187AC, 0xF4F44A15, 0x8D8D1559, 0xD6D682A8, 0xB9B9BC0A, 0x42420D9E,

    0xF6F6C16E, 0x2F2FB847, 0xDDDD06DF, 0x23233934, 0xCCCC6235, 0xF1F1C46A,

    0xC1C112CF, 0x8585EBDC, 0x8F8F9E22, 0x7171A1C9, 0x9090F0C0, 0xAAAA539B,

    0x0101F189, 0x8B8BE1D4, 0x4E4E8CED, 0x8E8E6FAB, 0xABABA212, 0x6F6F3EA2,

    0xE6E6540D, 0xDBDBF252, 0x92927BBB, 0xB7B7B602, 0x6969CA2F, 0x3939D9A9,

    0xD3D30CD7, 0xA7A72361, 0xA2A2AD1E, 0xC3C399B4, 0x6C6C4450, 0x07070504,

    0x04047FF6, 0x272746C2, 0xACACA716, 0xD0D07625, 0x50501386, 0xDCDCF756,

    0x84841A55, 0xE1E15109, 0x7A7A25BE, 0x1313EF91},

   {0xA9D93939, 0x67901717, 0xB3719C9C, 0xE8D2A6A6, 0x04050707, 0xFD985252,

    0xA3658080, 0x76DFE4E4, 0x9A084545, 0x92024B4B, 0x80A0E0E0, 0x78665A5A,

    0xE4DDAFAF, 0xDDB06A6A, 0xD1BF6363, 0x38362A2A, 0x0D54E6E6, 0xC6432020,

    0x3562CCCC, 0x98BEF2F2, 0x181E1212, 0xF724EBEB, 0xECD7A1A1, 0x6C774141,

    0x43BD2828, 0x7532BCBC, 0x37D47B7B, 0x269B8888, 0xFA700D0D, 0x13F94444,

    0x94B1FBFB, 0x485A7E7E, 0xF27A0303, 0xD0E48C8C, 0x8B47B6B6, 0x303C2424,

    0x84A5E7E7, 0x54416B6B, 0xDF06DDDD, 0x23C56060, 0x1945FDFD, 0x5BA33A3A,

    0x3D68C2C2, 0x59158D8D, 0xF321ECEC, 0xAE316666, 0xA23E6F6F, 0x82165757,

    0x63951010, 0x015BEFEF, 0x834DB8B8, 0x2E918686, 0xD9B56D6D, 0x511F8383,

    0x9B53AAAA, 0x7C635D5D, 0xA63B6868, 0xEB3FFEFE, 0xA5D63030, 0xBE257A7A,

    0x16A7ACAC, 0x0C0F0909, 0xE335F0F0, 0x6123A7A7, 0xC0F09090, 0x8CAFE9E9,

    0x3A809D9D, 0xF5925C5C, 0x73810C0C, 0x2C273131, 0x2576D0D0, 0x0BE75656,

    0xBB7B9292, 0x4EE9CECE, 0x89F10101, 0x6B9F1E1E, 0x53A93434, 0x6AC4F1F1,

    0xB499C3C3, 0xF1975B5B, 0xE1834747, 0xE66B1818, 0xBDC82222, 0x450E9898,

    0xE26E1F1F, 0xF4C9B3B3, 0xB62F7474, 0x66CBF8F8, 0xCCFF9999, 0x95EA1414,

    0x03ED5858, 0x56F7DCDC, 0xD4E18B8B, 0x1C1B1515, 0x1EADA2A2, 0xD70CD3D3,

    0xFB2BE2E2, 0xC31DC8C8, 0x8E195E5E, 0xB5C22C2C, 0xE9894949, 0xCF12C1C1,

    0xBF7E9595, 0xBA207D7D, 0xEA641111, 0x77840B0B, 0x396DC5C5, 0xAF6A8989,

    0x33D17C7C, 0xC9A17171, 0x62CEFFFF, 0x7137BBBB, 0x81FB0F0F, 0x793DB5B5,

    0x0951E1E1, 0xADDC3E3E, 0x242D3F3F, 0xCDA47676, 0xF99D5555, 0xD8EE8282,

    0xE5864040, 0xC5AE7878, 0xB9CD2525, 0x4D049696, 0x44557777, 0x080A0E0E,

    0x86135050, 0xE730F7F7, 0xA1D33737, 0x1D40FAFA, 0xAA346161, 0xED8C4E4E,

    0x06B3B0B0, 0x706C5454, 0xB22A7373, 0xD2523B3B, 0x410B9F9F, 0x7B8B0202,

    0xA088D8D8, 0x114FF3F3, 0x3167CBCB, 0xC2462727, 0x27C06767, 0x90B4FCFC,

    0x20283838, 0xF67F0404, 0x60784848, 0xFF2EE5E5, 0x96074C4C, 0x5C4B6565,

    0xB1C72B2B, 0xAB6F8E8E, 0x9E0D4242, 0x9CBBF5F5, 0x52F2DBDB, 0x1BF34A4A,

    0x5FA63D3D, 0x9359A4A4, 0x0ABCB9B9, 0xEF3AF9F9, 0x91EF1313, 0x85FE0808,

    0x49019191, 0xEE611616, 0x2D7CDEDE, 0x4FB22121, 0x8F42B1B1, 0x3BDB7272,

    0x47B82F2F, 0x8748BFBF, 0x6D2CAEAE, 0x46E3C0C0, 0xD6573C3C, 0x3E859A9A,

    0x6929A9A9, 0x647D4F4F, 0x2A948181, 0xCE492E2E, 0xCB17C6C6, 0x2FCA6969,

    0xFCC3BDBD, 0x975CA3A3, 0x055EE8E8, 0x7AD0EDED, 0xAC87D1D1, 0x7F8E0505,

    0xD5BA6464, 0x1AA8A5A5, 0x4BB72626, 0x0EB9BEBE, 0xA7608787, 0x5AF8D5D5,

    0x28223636, 0x14111B1B, 0x3FDE7575, 0x2979D9D9, 0x88AAEEEE, 0x3C332D2D,

    0x4C5F7979, 0x02B6B7B7, 0xB896CACA, 0xDA583535, 0xB09CC4C4, 0x17FC4343,

    0x551A8484, 0x1FF64D4D, 0x8A1C5959, 0x7D38B2B2, 0x57AC3333, 0xC718CFCF,

    0x8DF40606, 0x74695353, 0xB7749B9B, 0xC4F59797, 0x9F56ADAD, 0x72DAE3E3,

    0x7ED5EAEA, 0x154AF4F4, 0x229E8F8F, 0x12A2ABAB, 0x584E6262, 0x07E85F5F,

    0x99E51D1D, 0x34392323, 0x6EC1F6F6, 0x50446C6C, 0xDE5D3232, 0x68724646,

    0x6526A0A0, 0xBC93CDCD, 0xDB03DADA, 0xF8C6BABA, 0xC8FA9E9E, 0xA882D6D6,

    0x2BCF6E6E, 0x40507070, 0xDCEB8585, 0xFE750A0A, 0x328A9393, 0xA48DDFDF,

    0xCA4C2929, 0x10141C1C, 0x2173D7D7, 0xF0CCB4B4, 0xD309D4D4, 0x5D108A8A,

    0x0FE25151, 0x00000000, 0x6F9A1919, 0x9DE01A1A, 0x368F9494, 0x42E6C7C7,

    0x4AECC9C9, 0x5EFDD2D2, 0xC1AB7F7F, 0xE0D8A8A8},

   {0xBC75BC32, 0xECF3EC21, 0x20C62043, 0xB3F4B3C9, 0xDADBDA03, 0x027B028B,

    0xE2FBE22B, 0x9EC89EFA, 0xC94AC9EC, 0xD4D3D409, 0x18E6186B, 0x1E6B1E9F,

    0x9845980E, 0xB27DB238, 0xA6E8A6D2, 0x264B26B7, 0x3CD63C57, 0x9332938A,

    0x82D882EE, 0x52FD5298, 0x7B377BD4, 0xBB71BB37, 0x5BF15B97, 0x47E14783,

    0x2430243C, 0x510F51E2, 0xBAF8BAC6, 0x4A1B4AF3, 0xBF87BF48, 0x0DFA0D70,

    0xB006B0B3, 0x753F75DE, 0xD25ED2FD, 0x7DBA7D20, 0x66AE6631, 0x3A5B3AA3,

    0x598A591C, 0x00000000, 0xCDBCCD93, 0x1A9D1AE0, 0xAE6DAE2C, 0x7FC17FAB,

    0x2BB12BC7, 0xBE0EBEB9, 0xE080E0A0, 0x8A5D8A10, 0x3BD23B52, 0x64D564BA,

    0xD8A0D888, 0xE784E7A5, 0x5F075FE8, 0x1B141B11, 0x2CB52CC2, 0xFC90FCB4,

    0x312C3127, 0x80A38065, 0x73B2732A, 0x0C730C81, 0x794C795F, 0x6B546B41,

    0x4B924B02, 0x53745369, 0x9436948F, 0x8351831F, 0x2A382A36, 0xC4B0C49C,

    0x22BD22C8, 0xD55AD5F8, 0xBDFCBDC3, 0x48604878, 0xFF62FFCE, 0x4C964C07,

    0x416C4177, 0xC742C7E6, 0xEBF7EB24, 0x1C101C14, 0x5D7C5D63, 0x36283622,

    0x672767C0, 0xE98CE9AF, 0x441344F9, 0x149514EA, 0xF59CF5BB, 0xCFC7CF18,

    0x3F243F2D, 0xC046C0E3, 0x723B72DB, 0x5470546C, 0x29CA294C, 0xF0E3F035,

    0x088508FE, 0xC6CBC617, 0xF311F34F, 0x8CD08CE4, 0xA493A459, 0xCAB8CA96,

    0x68A6683B, 0xB883B84D, 0x38203828, 0xE5FFE52E, 0xAD9FAD56, 0x0B770B84,

    0xC8C3C81D, 0x99CC99FF, 0x580358ED, 0x196F199A, 0x0E080E0A, 0x95BF957E,

    0x70407050, 0xF7E7F730, 0x6E2B6ECF, 0x1FE21F6E, 0xB579B53D, 0x090C090F,

    0x61AA6134, 0x57825716, 0x9F419F0B, 0x9D3A9D80, 0x11EA1164, 0x25B925CD,

    0xAFE4AFDD, 0x459A4508, 0xDFA4DF8D, 0xA397A35C, 0xEA7EEAD5, 0x35DA3558,

    0xED7AEDD0, 0x431743FC, 0xF866F8CB, 0xFB94FBB1, 0x37A137D3, 0xFA1DFA40,

    0xC23DC268, 0xB4F0B4CC, 0x32DE325D, 0x9CB39C71, 0x560B56E7, 0xE372E3DA,

    0x87A78760, 0x151C151B, 0xF9EFF93A, 0x63D163BF, 0x345334A9, 0x9A3E9A85,

    0xB18FB142, 0x7C337CD1, 0x8826889B, 0x3D5F3DA6, 0xA1ECA1D7, 0xE476E4DF,

    0x812A8194, 0x91499101, 0x0F810FFB, 0xEE88EEAA, 0x16EE1661, 0xD721D773,

    0x97C497F5, 0xA51AA5A8, 0xFEEBFE3F, 0x6DD96DB5, 0x78C578AE, 0xC539C56D,

    0x1D991DE5, 0x76CD76A4, 0x3EAD3EDC, 0xCB31CB67, 0xB68BB647, 0xEF01EF5B,

    0x1218121E, 0x602360C5, 0x6ADD6AB0, 0x4D1F4DF6, 0xCE4ECEE9, 0xDE2DDE7C,

    0x55F9559D, 0x7E487E5A, 0x214F21B2, 0x03F2037A, 0xA065A026, 0x5E8E5E19,

    0x5A785A66, 0x655C654B, 0x6258624E, 0xFD19FD45, 0x068D06F4, 0x40E54086,

    0xF298F2BE, 0x335733AC, 0x17671790, 0x057F058E, 0xE805E85E, 0x4F644F7D,

    0x89AF896A, 0x10631095, 0x74B6742F, 0x0AFE0A75, 0x5CF55C92, 0x9BB79B74,

    0x2D3C2D33, 0x30A530D6, 0x2ECE2E49, 0x49E94989, 0x46684672, 0x77447755,

    0xA8E0A8D8, 0x964D9604, 0x284328BD, 0xA969A929, 0xD929D979, 0x862E8691,

    0xD1ACD187, 0xF415F44A, 0x8D598D15, 0xD6A8D682, 0xB90AB9BC, 0x429E420D,

    0xF66EF6C1, 0x2F472FB8, 0xDDDFDD06, 0x23342339, 0xCC35CC62, 0xF16AF1C4,

    0xC1CFC112, 0x85DC85EB, 0x8F228F9E, 0x71C971A1, 0x90C090F0, 0xAA9BAA53,

    0x018901F1, 0x8BD48BE1, 0x4EED4E8C, 0x8EAB8E6F, 0xAB12ABA2, 0x6FA26F3E,

    0xE60DE654, 0xDB52DBF2, 0x92BB927B, 0xB702B7B6, 0x692F69CA, 0x39A939D9,

    0xD3D7D30C, 0xA761A723, 0xA21EA2AD, 0xC3B4C399, 0x6C506C44, 0x07040705,

    0x04F6047F, 0x27C22746, 0xAC16ACA7, 0xD025D076, 0x50865013, 0xDC56DCF7,

    0x8455841A, 0xE109E151, 0x7ABE7A25, 0x139113EF},

   {0xD939A9D9, 0x90176790, 0x719CB371, 0xD2A6E8D2, 0x05070405, 0x9852FD98,

    0x6580A365, 0xDFE476DF, 0x08459A08, 0x024B9202, 0xA0E080A0, 0x665A7866,

    0xDDAFE4DD, 0xB06ADDB0, 0xBF63D1BF, 0x362A3836, 0x54E60D54, 0x4320C643,

    0x62CC3562, 0xBEF298BE, 0x1E12181E, 0x24EBF724, 0xD7A1ECD7, 0x77416C77,

    0xBD2843BD, 0x32BC7532, 0xD47B37D4, 0x9B88269B, 0x700DFA70, 0xF94413F9,

    0xB1FB94B1, 0x5A7E485A, 0x7A03F27A, 0xE48CD0E4, 0x47B68B47, 0x3C24303C,

    0xA5E784A5, 0x416B5441, 0x06DDDF06, 0xC56023C5, 0x45FD1945, 0xA33A5BA3,

    0x68C23D68, 0x158D5915, 0x21ECF321, 0x3166AE31, 0x3E6FA23E, 0x16578216,

    0x95106395, 0x5BEF015B, 0x4DB8834D, 0x91862E91, 0xB56DD9B5, 0x1F83511F,

    0x53AA9B53, 0x635D7C63, 0x3B68A63B, 0x3FFEEB3F, 0xD630A5D6, 0x257ABE25,

    0xA7AC16A7, 0x0F090C0F, 0x35F0E335, 0x23A76123, 0xF090C0F0, 0xAFE98CAF,

    0x809D3A80, 0x925CF592, 0x810C7381, 0x27312C27, 0x76D02576, 0xE7560BE7,

    0x7B92BB7B, 0xE9CE4EE9, 0xF10189F1, 0x9F1E6B9F, 0xA93453A9, 0xC4F16AC4,

    0x99C3B499, 0x975BF197, 0x8347E183, 0x6B18E66B, 0xC822BDC8, 0x0E98450E,

    0x6E1FE26E, 0xC9B3F4C9, 0x2F74B62F, 0xCBF866CB, 0xFF99CCFF, 0xEA1495EA,

    0xED5803ED, 0xF7DC56F7, 0xE18BD4E1, 0x1B151C1B, 0xADA21EAD, 0x0CD3D70C,

    0x2BE2FB2B, 0x1DC8C31D, 0x195E8E19, 0xC22CB5C2, 0x8949E989, 0x12C1CF12,

    0x7E95BF7E, 0x207DBA20, 0x6411EA64, 0x840B7784, 0x6DC5396D, 0x6A89AF6A,

    0xD17C33D1, 0xA171C9A1, 0xCEFF62CE, 0x37BB7137, 0xFB0F81FB, 0x3DB5793D,

    0x51E10951, 0xDC3EADDC, 0x2D3F242D, 0xA476CDA4, 0x9D55F99D, 0xEE82D8EE,

    0x8640E586, 0xAE78C5AE, 0xCD25B9CD, 0x04964D04, 0x55774455, 0x0A0E080A,

    0x13508613, 0x30F7E730, 0xD337A1D3, 0x40FA1D40, 0x3461AA34, 0x8C4EED8C,

    0xB3B006B3, 0x6C54706C, 0x2A73B22A, 0x523BD252, 0x0B9F410B, 0x8B027B8B,

    0x88D8A088, 0x4FF3114F, 0x67CB3167, 0x4627C246, 0xC06727C0, 0xB4FC90B4,

    0x28382028, 0x7F04F67F, 0x78486078, 0x2EE5FF2E, 0x074C9607, 0x4B655C4B,

    0xC72BB1C7, 0x6F8EAB6F, 0x0D429E0D, 0xBBF59CBB, 0xF2DB52F2, 0xF34A1BF3,

    0xA63D5FA6, 0x59A49359, 0xBCB90ABC, 0x3AF9EF3A, 0xEF1391EF, 0xFE0885FE,

    0x01914901, 0x6116EE61, 0x7CDE2D7C, 0xB2214FB2, 0x42B18F42, 0xDB723BDB,

    0xB82F47B8, 0x48BF8748, 0x2CAE6D2C, 0xE3C046E3, 0x573CD657, 0x859A3E85,

    0x29A96929, 0x7D4F647D, 0x94812A94, 0x492ECE49, 0x17C6CB17, 0xCA692FCA,

    0xC3BDFCC3, 0x5CA3975C, 0x5EE8055E, 0xD0ED7AD0, 0x87D1AC87, 0x8E057F8E,

    0xBA64D5BA, 0xA8A51AA8, 0xB7264BB7, 0xB9BE0EB9, 0x6087A760, 0xF8D55AF8,

    0x22362822, 0x111B1411, 0xDE753FDE, 0x79D92979, 0xAAEE88AA, 0x332D3C33,

    0x5F794C5F, 0xB6B702B6, 0x96CAB896, 0x5835DA58, 0x9CC4B09C, 0xFC4317FC,

    0x1A84551A, 0xF64D1FF6, 0x1C598A1C, 0x38B27D38, 0xAC3357AC, 0x18CFC718,

    0xF4068DF4, 0x69537469, 0x749BB774, 0xF597C4F5, 0x56AD9F56, 0xDAE372DA,

    0xD5EA7ED5, 0x4AF4154A, 0x9E8F229E, 0xA2AB12A2, 0x4E62584E, 0xE85F07E8,

    0xE51D99E5, 0x39233439, 0xC1F66EC1, 0x446C5044, 0x5D32DE5D, 0x72466872,

    0x26A06526, 0x93CDBC93, 0x03DADB03, 0xC6BAF8C6, 0xFA9EC8FA, 0x82D6A882,

    0xCF6E2BCF, 0x50704050, 0xEB85DCEB, 0x750AFE75, 0x8A93328A, 0x8DDFA48D,

    0x4C29CA4C, 0x141C1014, 0x73D72173, 0xCCB4F0CC, 0x09D4D309, 0x108A5D10,

    0xE2510FE2, 0x00000000, 0x9A196F9A, 0xE01A9DE0, 0x8F94368F, 0xE6C742E6,

    0xECC94AEC, 0xFDD25EFD, 0xAB7FC1AB, 0xD8A8E0D8}

};

/* The exp_to_poly and poly_to_exp tables are used to perform efficient

 * operations in GF(2^8) represented as GF(2)[x]/w(x) where

 * w(x)=x^8+x^6+x^3+x^2+1.  We care about doing that because it's part of the

 * definition of the RS matrix in the key schedule.  Elements of that field

 * are polynomials of degree not greater than 7 and all coefficients 0 or 1,

 * which can be represented naturally by bytes (just substitute x=2).  In that

 * form, GF(2^8) addition is the same as bitwise XOR, but GF(2^8)

 * multiplication is inefficient without hardware support.  To multiply

 * faster, I make use of the fact x is a generator for the nonzero elements,

 * so that every element p of GF(2)[x]/w(x) is either 0 or equal to (x)^n for

 * some n in 0..254.  Note that that caret is exponentiation in GF(2^8),

 * *not* polynomial notation.  So if I want to compute pq where p and q are

 * in GF(2^8), I can just say:

 *    1. if p=0 or q=0 then pq=0

 *    2. otherwise, find m and n such that p=x^m and q=x^n

 *    3. pq=(x^m)(x^n)=x^(m+n), so add m and n and find pq

 * The translations in steps 2 and 3 are looked up in the tables

 * poly_to_exp (for step 2) and exp_to_poly (for step 3).  To see this

 * in action, look at the CALC_S macro.  As additional wrinkles, note that

 * one of my operands is always a constant, so the poly_to_exp lookup on it

 * is done in advance; I included the original values in the comments so

 * readers can have some chance of recognizing that this *is* the RS matrix

 * from the Twofish paper.  I've only included the table entries I actually

 * need; I never do a lookup on a variable input of zero and the biggest

 * exponents I'll ever see are 254 (variable) and 237 (constant), so they'll

 * never sum to more than 491.    I'm repeating part of the exp_to_poly table

 * so that I don't have to do mod-255 reduction in the exponent arithmetic.

 * Since I know my constant operands are never zero, I only have to worry

 * about zero values in the variable operand, and I do it with a simple

 * conditional branch.    I know conditionals are expensive, but I couldn't

 * see a non-horrible way of avoiding them, and I did manage to group the

 * statements so that each if covers four group multiplications. */

static const u8 poly_to_exp[255] = {

   0x00, 0x01, 0x17, 0x02, 0x2E, 0x18, 0x53, 0x03, 0x6A, 0x2F, 0x93, 0x19,

   0x34, 0x54, 0x45, 0x04, 0x5C, 0x6B, 0xB6, 0x30, 0xA6, 0x94, 0x4B, 0x1A,

   0x8C, 0x35, 0x81, 0x55, 0xAA, 0x46, 0x0D, 0x05, 0x24, 0x5D, 0x87, 0x6C,

   0x9B, 0xB7, 0xC1, 0x31, 0x2B, 0xA7, 0xA3, 0x95, 0x98, 0x4C, 0xCA, 0x1B,

   0xE6, 0x8D, 0x73, 0x36, 0xCD, 0x82, 0x12, 0x56, 0x62, 0xAB, 0xF0, 0x47,

   0x4F, 0x0E, 0xBD, 0x06, 0xD4, 0x25, 0xD2, 0x5E, 0x27, 0x88, 0x66, 0x6D,

   0xD6, 0x9C, 0x79, 0xB8, 0x08, 0xC2, 0xDF, 0x32, 0x68, 0x2C, 0xFD, 0xA8,

   0x8A, 0xA4, 0x5A, 0x96, 0x29, 0x99, 0x22, 0x4D, 0x60, 0xCB, 0xE4, 0x1C,

   0x7B, 0xE7, 0x3B, 0x8E, 0x9E, 0x74, 0xF4, 0x37, 0xD8, 0xCE, 0xF9, 0x83,

   0x6F, 0x13, 0xB2, 0x57, 0xE1, 0x63, 0xDC, 0xAC, 0xC4, 0xF1, 0xAF, 0x48,

   0x0A, 0x50, 0x42, 0x0F, 0xBA, 0xBE, 0xC7, 0x07, 0xDE, 0xD5, 0x78, 0x26,

   0x65, 0xD3, 0xD1, 0x5F, 0xE3, 0x28, 0x21, 0x89, 0x59, 0x67, 0xFC, 0x6E,

   0xB1, 0xD7, 0xF8, 0x9D, 0xF3, 0x7A, 0x3A, 0xB9, 0xC6, 0x09, 0x41, 0xC3,

   0xAE, 0xE0, 0xDB, 0x33, 0x44, 0x69, 0x92, 0x2D, 0x52, 0xFE, 0x16, 0xA9,

   0x0C, 0x8B, 0x80, 0xA5, 0x4A, 0x5B, 0xB5, 0x97, 0xC9, 0x2A, 0xA2, 0x9A,

   0xC0, 0x23, 0x86, 0x4E, 0xBC, 0x61, 0xEF, 0xCC, 0x11, 0xE5, 0x72, 0x1D,

   0x3D, 0x7C, 0xEB, 0xE8, 0xE9, 0x3C, 0xEA, 0x8F, 0x7D, 0x9F, 0xEC, 0x75,

   0x1E, 0xF5, 0x3E, 0x38, 0xF6, 0xD9, 0x3F, 0xCF, 0x76, 0xFA, 0x1F, 0x84,

   0xA0, 0x70, 0xED, 0x14, 0x90, 0xB3, 0x7E, 0x58, 0xFB, 0xE2, 0x20, 0x64,

   0xD0, 0xDD, 0x77, 0xAD, 0xDA, 0xC5, 0x40, 0xF2, 0x39, 0xB0, 0xF7, 0x49,

   0xB4, 0x0B, 0x7F, 0x51, 0x15, 0x43, 0x91, 0x10, 0x71, 0xBB, 0xEE, 0xBF,

   0x85, 0xC8, 0xA1

};

static const u8 exp_to_poly[492] = {

   0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x4D, 0x9A, 0x79, 0xF2,

   0xA9, 0x1F, 0x3E, 0x7C, 0xF8, 0xBD, 0x37, 0x6E, 0xDC, 0xF5, 0xA7, 0x03,

   0x06, 0x0C, 0x18, 0x30, 0x60, 0xC0, 0xCD, 0xD7, 0xE3, 0x8B, 0x5B, 0xB6,

   0x21, 0x42, 0x84, 0x45, 0x8A, 0x59, 0xB2, 0x29, 0x52, 0xA4, 0x05, 0x0A,

   0x14, 0x28, 0x50, 0xA0, 0x0D, 0x1A, 0x34, 0x68, 0xD0, 0xED, 0x97, 0x63,

   0xC6, 0xC1, 0xCF, 0xD3, 0xEB, 0x9B, 0x7B, 0xF6, 0xA1, 0x0F, 0x1E, 0x3C,

   0x78, 0xF0, 0xAD, 0x17, 0x2E, 0x5C, 0xB8, 0x3D, 0x7A, 0xF4, 0xA5, 0x07,

   0x0E, 0x1C, 0x38, 0x70, 0xE0, 0x8D, 0x57, 0xAE, 0x11, 0x22, 0x44, 0x88,

   0x5D, 0xBA, 0x39, 0x72, 0xE4, 0x85, 0x47, 0x8E, 0x51, 0xA2, 0x09, 0x12,

   0x24, 0x48, 0x90, 0x6D, 0xDA, 0xF9, 0xBF, 0x33, 0x66, 0xCC, 0xD5, 0xE7,

   0x83, 0x4B, 0x96, 0x61, 0xC2, 0xC9, 0xDF, 0xF3, 0xAB, 0x1B, 0x36, 0x6C,

   0xD8, 0xFD, 0xB7, 0x23, 0x46, 0x8C, 0x55, 0xAA, 0x19, 0x32, 0x64, 0xC8,

   0xDD, 0xF7, 0xA3, 0x0B, 0x16, 0x2C, 0x58, 0xB0, 0x2D, 0x5A, 0xB4, 0x25,

   0x4A, 0x94, 0x65, 0xCA, 0xD9, 0xFF, 0xB3, 0x2B, 0x56, 0xAC, 0x15, 0x2A,

   0x54, 0xA8, 0x1D, 0x3A, 0x74, 0xE8, 0x9D, 0x77, 0xEE, 0x91, 0x6F, 0xDE,

   0xF1, 0xAF, 0x13, 0x26, 0x4C, 0x98, 0x7D, 0xFA, 0xB9, 0x3F, 0x7E, 0xFC,

   0xB5, 0x27, 0x4E, 0x9C, 0x75, 0xEA, 0x99, 0x7F, 0xFE, 0xB1, 0x2F, 0x5E,

   0xBC, 0x35, 0x6A, 0xD4, 0xE5, 0x87, 0x43, 0x86, 0x41, 0x82, 0x49, 0x92,

   0x69, 0xD2, 0xE9, 0x9F, 0x73, 0xE6, 0x81, 0x4F, 0x9E, 0x71, 0xE2, 0x89,

   0x5F, 0xBE, 0x31, 0x62, 0xC4, 0xC5, 0xC7, 0xC3, 0xCB, 0xDB, 0xFB, 0xBB,

   0x3B, 0x76, 0xEC, 0x95, 0x67, 0xCE, 0xD1, 0xEF, 0x93, 0x6B, 0xD6, 0xE1,

   0x8F, 0x53, 0xA6, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x4D,

   0x9A, 0x79, 0xF2, 0xA9, 0x1F, 0x3E, 0x7C, 0xF8, 0xBD, 0x37, 0x6E, 0xDC,

   0xF5, 0xA7, 0x03, 0x06, 0x0C, 0x18, 0x30, 0x60, 0xC0, 0xCD, 0xD7, 0xE3,

   0x8B, 0x5B, 0xB6, 0x21, 0x42, 0x84, 0x45, 0x8A, 0x59, 0xB2, 0x29, 0x52,

   0xA4, 0x05, 0x0A, 0x14, 0x28, 0x50, 0xA0, 0x0D, 0x1A, 0x34, 0x68, 0xD0,

   0xED, 0x97, 0x63, 0xC6, 0xC1, 0xCF, 0xD3, 0xEB, 0x9B, 0x7B, 0xF6, 0xA1,

   0x0F, 0x1E, 0x3C, 0x78, 0xF0, 0xAD, 0x17, 0x2E, 0x5C, 0xB8, 0x3D, 0x7A,

   0xF4, 0xA5, 0x07, 0x0E, 0x1C, 0x38, 0x70, 0xE0, 0x8D, 0x57, 0xAE, 0x11,

   0x22, 0x44, 0x88, 0x5D, 0xBA, 0x39, 0x72, 0xE4, 0x85, 0x47, 0x8E, 0x51,

   0xA2, 0x09, 0x12, 0x24, 0x48, 0x90, 0x6D, 0xDA, 0xF9, 0xBF, 0x33, 0x66,

   0xCC, 0xD5, 0xE7, 0x83, 0x4B, 0x96, 0x61, 0xC2, 0xC9, 0xDF, 0xF3, 0xAB,

   0x1B, 0x36, 0x6C, 0xD8, 0xFD, 0xB7, 0x23, 0x46, 0x8C, 0x55, 0xAA, 0x19,

   0x32, 0x64, 0xC8, 0xDD, 0xF7, 0xA3, 0x0B, 0x16, 0x2C, 0x58, 0xB0, 0x2D,

   0x5A, 0xB4, 0x25, 0x4A, 0x94, 0x65, 0xCA, 0xD9, 0xFF, 0xB3, 0x2B, 0x56,

   0xAC, 0x15, 0x2A, 0x54, 0xA8, 0x1D, 0x3A, 0x74, 0xE8, 0x9D, 0x77, 0xEE,

   0x91, 0x6F, 0xDE, 0xF1, 0xAF, 0x13, 0x26, 0x4C, 0x98, 0x7D, 0xFA, 0xB9,

   0x3F, 0x7E, 0xFC, 0xB5, 0x27, 0x4E, 0x9C, 0x75, 0xEA, 0x99, 0x7F, 0xFE,

   0xB1, 0x2F, 0x5E, 0xBC, 0x35, 0x6A, 0xD4, 0xE5, 0x87, 0x43, 0x86, 0x41,

   0x82, 0x49, 0x92, 0x69, 0xD2, 0xE9, 0x9F, 0x73, 0xE6, 0x81, 0x4F, 0x9E,

   0x71, 0xE2, 0x89, 0x5F, 0xBE, 0x31, 0x62, 0xC4, 0xC5, 0xC7, 0xC3, 0xCB

};

/* The table constants are indices of

 * S-box entries, preprocessed through q0 and q1. */

static const u8 calc_sb_tbl[512] = {

    0xA9, 0x75, 0x67, 0xF3, 0xB3, 0xC6, 0xE8, 0xF4,

    0x04, 0xDB, 0xFD, 0x7B, 0xA3, 0xFB, 0x76, 0xC8,

    0x9A, 0x4A, 0x92, 0xD3, 0x80, 0xE6, 0x78, 0x6B,

    0xE4, 0x45, 0xDD, 0x7D, 0xD1, 0xE8, 0x38, 0x4B,

    0x0D, 0xD6, 0xC6, 0x32, 0x35, 0xD8, 0x98, 0xFD,

    0x18, 0x37, 0xF7, 0x71, 0xEC, 0xF1, 0x6C, 0xE1,

    0x43, 0x30, 0x75, 0x0F, 0x37, 0xF8, 0x26, 0x1B,

    0xFA, 0x87, 0x13, 0xFA, 0x94, 0x06, 0x48, 0x3F,

    0xF2, 0x5E, 0xD0, 0xBA, 0x8B, 0xAE, 0x30, 0x5B,

    0x84, 0x8A, 0x54, 0x00, 0xDF, 0xBC, 0x23, 0x9D,

    0x19, 0x6D, 0x5B, 0xC1, 0x3D, 0xB1, 0x59, 0x0E,

    0xF3, 0x80, 0xAE, 0x5D, 0xA2, 0xD2, 0x82, 0xD5,

    0x63, 0xA0, 0x01, 0x84, 0x83, 0x07, 0x2E, 0x14,

    0xD9, 0xB5, 0x51, 0x90, 0x9B, 0x2C, 0x7C, 0xA3,

    0xA6, 0xB2, 0xEB, 0x73, 0xA5, 0x4C, 0xBE, 0x54,

    0x16, 0x92, 0x0C, 0x74, 0xE3, 0x36, 0x61, 0x51,

    0xC0, 0x38, 0x8C, 0xB0, 0x3A, 0xBD, 0xF5, 0x5A,

    0x73, 0xFC, 0x2C, 0x60, 0x25, 0x62, 0x0B, 0x96,

    0xBB, 0x6C, 0x4E, 0x42, 0x89, 0xF7, 0x6B, 0x10,

    0x53, 0x7C, 0x6A, 0x28, 0xB4, 0x27, 0xF1, 0x8C,

    0xE1, 0x13, 0xE6, 0x95, 0xBD, 0x9C, 0x45, 0xC7,

    0xE2, 0x24, 0xF4, 0x46, 0xB6, 0x3B, 0x66, 0x70,

    0xCC, 0xCA, 0x95, 0xE3, 0x03, 0x85, 0x56, 0xCB,

    0xD4, 0x11, 0x1C, 0xD0, 0x1E, 0x93, 0xD7, 0xB8,

    0xFB, 0xA6, 0xC3, 0x83, 0x8E, 0x20, 0xB5, 0xFF,

    0xE9, 0x9F, 0xCF, 0x77, 0xBF, 0xC3, 0xBA, 0xCC,

    0xEA, 0x03, 0x77, 0x6F, 0x39, 0x08, 0xAF, 0xBF,

    0x33, 0x40, 0xC9, 0xE7, 0x62, 0x2B, 0x71, 0xE2,

    0x81, 0x79, 0x79, 0x0C, 0x09, 0xAA, 0xAD, 0x82,

    0x24, 0x41, 0xCD, 0x3A, 0xF9, 0xEA, 0xD8, 0xB9,

    0xE5, 0xE4, 0xC5, 0x9A, 0xB9, 0xA4, 0x4D, 0x97,

    0x44, 0x7E, 0x08, 0xDA, 0x86, 0x7A, 0xE7, 0x17,

    0xA1, 0x66, 0x1D, 0x94, 0xAA, 0xA1, 0xED, 0x1D,

    0x06, 0x3D, 0x70, 0xF0, 0xB2, 0xDE, 0xD2, 0xB3,

    0x41, 0x0B, 0x7B, 0x72, 0xA0, 0xA7, 0x11, 0x1C,

    0x31, 0xEF, 0xC2, 0xD1, 0x27, 0x53, 0x90, 0x3E,

    0x20, 0x8F, 0xF6, 0x33, 0x60, 0x26, 0xFF, 0x5F,

    0x96, 0xEC, 0x5C, 0x76, 0xB1, 0x2A, 0xAB, 0x49,

    0x9E, 0x81, 0x9C, 0x88, 0x52, 0xEE, 0x1B, 0x21,

    0x5F, 0xC4, 0x93, 0x1A, 0x0A, 0xEB, 0xEF, 0xD9,

    0x91, 0xC5, 0x85, 0x39, 0x49, 0x99, 0xEE, 0xCD,

    0x2D, 0xAD, 0x4F, 0x31, 0x8F, 0x8B, 0x3B, 0x01,

    0x47, 0x18, 0x87, 0x23, 0x6D, 0xDD, 0x46, 0x1F,

    0xD6, 0x4E, 0x3E, 0x2D, 0x69, 0xF9, 0x64, 0x48,

    0x2A, 0x4F, 0xCE, 0xF2, 0xCB, 0x65, 0x2F, 0x8E,

    0xFC, 0x78, 0x97, 0x5C, 0x05, 0x58, 0x7A, 0x19,

    0xAC, 0x8D, 0x7F, 0xE5, 0xD5, 0x98, 0x1A, 0x57,

    0x4B, 0x67, 0x0E, 0x7F, 0xA7, 0x05, 0x5A, 0x64,

    0x28, 0xAF, 0x14, 0x63, 0x3F, 0xB6, 0x29, 0xFE,

    0x88, 0xF5, 0x3C, 0xB7, 0x4C, 0x3C, 0x02, 0xA5,

    0xB8, 0xCE, 0xDA, 0xE9, 0xB0, 0x68, 0x17, 0x44,

    0x55, 0xE0, 0x1F, 0x4D, 0x8A, 0x43, 0x7D, 0x69,

    0x57, 0x29, 0xC7, 0x2E, 0x8D, 0xAC, 0x74, 0x15,

    0xB7, 0x59, 0xC4, 0xA8, 0x9F, 0x0A, 0x72, 0x9E,

    0x7E, 0x6E, 0x15, 0x47, 0x22, 0xDF, 0x12, 0x34,

    0x58, 0x35, 0x07, 0x6A, 0x99, 0xCF, 0x34, 0xDC,

    0x6E, 0x22, 0x50, 0xC9, 0xDE, 0xC0, 0x68, 0x9B,

    0x65, 0x89, 0xBC, 0xD4, 0xDB, 0xED, 0xF8, 0xAB,

    0xC8, 0x12, 0xA8, 0xA2, 0x2B, 0x0D, 0x40, 0x52,

    0xDC, 0xBB, 0xFE, 0x02, 0x32, 0x2F, 0xA4, 0xA9,

    0xCA, 0xD7, 0x10, 0x61, 0x21, 0x1E, 0xF0, 0xB4,

    0xD3, 0x50, 0x5D, 0x04, 0x0F, 0xF6, 0x00, 0xC2,

    0x6F, 0x16, 0x9D, 0x25, 0x36, 0x86, 0x42, 0x56,

    0x4A, 0x55, 0x5E, 0x09, 0xC1, 0xBE, 0xE0, 0x91

};

/* Macro to perform one column of the RS matrix multiplication.  The

 * parameters a, b, c, and d are the four bytes of output; i is the index

 * of the key bytes, and w, x, y, and z, are the column of constants from

 * the RS matrix, preprocessed through the poly_to_exp table. */

#define CALC_S(a, b, c, d, i, w, x, y, z) \

   if (key[i]) { \

      tmp = poly_to_exp[key[i] - 1]; \

      (a) ^= exp_to_poly[tmp + (w)]; \

      (b) ^= exp_to_poly[tmp + (x)]; \

      (c) ^= exp_to_poly[tmp + (y)]; \

      (d) ^= exp_to_poly[tmp + (z)]; \

   }

/* Macros to calculate the key-dependent S-boxes for a 128-bit key using

 * the S vector from CALC_S.  CALC_SB_2 computes a single entry in all

 * four S-boxes, where i is the index of the entry to compute, and a and b

 * are the index numbers preprocessed through the q0 and q1 tables

 * respectively. */

#define CALC_SB_2(i, a, b) \

   ctx->s[0][i] = mds[0][q0[(a) ^ sa] ^ se]; \

   ctx->s[1][i] = mds[1][q0[(b) ^ sb] ^ sf]; \

   ctx->s[2][i] = mds[2][q1[(a) ^ sc] ^ sg]; \

   ctx->s[3][i] = mds[3][q1[(b) ^ sd] ^ sh]

/* Macro exactly like CALC_SB_2, but for 192-bit keys. */

#define CALC_SB192_2(i, a, b) \

   ctx->s[0][i] = mds[0][q0[q0[(b) ^ sa] ^ se] ^ si]; \

   ctx->s[1][i] = mds[1][q0[q1[(b) ^ sb] ^ sf] ^ sj]; \

   ctx->s[2][i] = mds[2][q1[q0[(a) ^ sc] ^ sg] ^ sk]; \

   ctx->s[3][i] = mds[3][q1[q1[(a) ^ sd] ^ sh] ^ sl];

/* Macro exactly like CALC_SB_2, but for 256-bit keys. */

#define CALC_SB256_2(i, a, b) \

   ctx->s[0][i] = mds[0][q0[q0[q1[(b) ^ sa] ^ se] ^ si] ^ sm]; \

   ctx->s[1][i] = mds[1][q0[q1[q1[(a) ^ sb] ^ sf] ^ sj] ^ sn]; \

   ctx->s[2][i] = mds[2][q1[q0[q0[(a) ^ sc] ^ sg] ^ sk] ^ so]; \

   ctx->s[3][i] = mds[3][q1[q1[q0[(b) ^ sd] ^ sh] ^ sl] ^ sp];

/* Macros to calculate the whitening and round subkeys.  CALC_K_2 computes the

 * last two stages of the h() function for a given index (either 2i or 2i+1).

 * a, b, c, and d are the four bytes going into the last two stages.  For

 * 128-bit keys, this is the entire h() function and a and c are the index

 * preprocessed through q0 and q1 respectively; for longer keys they are the

 * output of previous stages.  j is the index of the first key byte to use.

 * CALC_K computes a pair of subkeys for 128-bit Twofish, by calling CALC_K_2

 * twice, doing the Psuedo-Hadamard Transform, and doing the necessary

 * rotations.  Its parameters are: a, the array to write the results into,

 * j, the index of the first output entry, k and l, the preprocessed indices

 * for index 2i, and m and n, the preprocessed indices for index 2i+1.

 * CALC_K192_2 expands CALC_K_2 to handle 192-bit keys, by doing an

 * additional lookup-and-XOR stage.  The parameters a, b, c and d are the

 * four bytes going into the last three stages.  For 192-bit keys, c = d

 * are the index preprocessed through q0, and a = b are the index

 * preprocessed through q1; j is the index of the first key byte to use.

 * CALC_K192 is identical to CALC_K but for using the CALC_K192_2 macro

 * instead of CALC_K_2.

 * CALC_K256_2 expands CALC_K192_2 to handle 256-bit keys, by doing an

 * additional lookup-and-XOR stage.  The parameters a and b are the index

 * preprocessed through q0 and q1 respectively; j is the index of the first

 * key byte to use.  CALC_K256 is identical to CALC_K but for using the

 * CALC_K256_2 macro instead of CALC_K_2. */

#define CALC_K_2(a, b, c, d, j) \

     mds[0][q0[a ^ key[(j) + 8]] ^ key[j]] \

   ^ mds[1][q0[b ^ key[(j) + 9]] ^ key[(j) + 1]] \

   ^ mds[2][q1[c ^ key[(j) + 10]] ^ key[(j) + 2]] \

   ^ mds[3][q1[d ^ key[(j) + 11]] ^ key[(j) + 3]]

#define CALC_K(a, j, k, l, m, n) \

   x = CALC_K_2 (k, l, k, l, 0); \

   y = CALC_K_2 (m, n, m, n, 4); \

   y = (y << 8) + (y >> 24); \

   x += y; y += x; ctx->a[j] = x; \

   ctx->a[(j) + 1] = (y << 9) + (y >> 23)

#define CALC_K192_2(a, b, c, d, j) \

   CALC_K_2 (q0[a ^ key[(j) + 16]], \

         q1[b ^ key[(j) + 17]], \

         q0[c ^ key[(j) + 18]], \

         q1[d ^ key[(j) + 19]], j)

#define CALC_K192(a, j, k, l, m, n) \

   x = CALC_K192_2 (l, l, k, k, 0); \

   y = CALC_K192_2 (n, n, m, m, 4); \

   y = (y << 8) + (y >> 24); \

   x += y; y += x; ctx->a[j] = x; \

   ctx->a[(j) + 1] = (y << 9) + (y >> 23)

#define CALC_K256_2(a, b, j) \

   CALC_K192_2 (q1[b ^ key[(j) + 24]], \

            q1[a ^ key[(j) + 25]], \

            q0[a ^ key[(j) + 26]], \

            q0[b ^ key[(j) + 27]], j)

#define CALC_K256(a, j, k, l, m, n) \

   x = CALC_K256_2 (k, l, 0); \

   y = CALC_K256_2 (m, n, 4); \

   y = (y << 8) + (y >> 24); \

   x += y; y += x; ctx->a[j] = x; \

   ctx->a[(j) + 1] = (y << 9) + (y >> 23)

/* Perform the key setup. */

int twofish_set_key (twofish_context *ctx,

                const unsigned char *key, int key_len)

{

    int i, j, k;

    /* Temporaries for CALC_K. */

    u32 x, y;

    /* The S vector used to key the S-boxes, split up into individual bytes.

     * 128-bit keys use only sa through sh; 256-bit use all of them. */

    u8 sa = 0, sb = 0, sc = 0, sd = 0, se = 0, sf = 0, sg = 0, sh = 0;

    u8 si = 0, sj = 0, sk = 0, sl = 0, sm = 0, sn = 0, so = 0, sp = 0;

    /* Temporary for CALC_S. */

    u8 tmp;

    /* Check key length. */

    if (key_len != 16 && key_len != 24 && key_len != 32)

        return -1; /* unsupported key length */

    /* Compute the first two words of the S vector.  The magic numbers are

     * the entries of the RS matrix, preprocessed through poly_to_exp. The

     * numbers in the comments are the original (polynomial form) matrix

     * entries. */

    CALC_S (sa, sb, sc, sd, 0, 0x00, 0x2D, 0x01, 0x2D); /* 01 A4 02 A4 */

    CALC_S (sa, sb, sc, sd, 1, 0x2D, 0xA4, 0x44, 0x8A); /* A4 56 A1 55 */

    CALC_S (sa, sb, sc, sd, 2, 0x8A, 0xD5, 0xBF, 0xD1); /* 55 82 FC 87 */

    CALC_S (sa, sb, sc, sd, 3, 0xD1, 0x7F, 0x3D, 0x99); /* 87 F3 C1 5A */

    CALC_S (sa, sb, sc, sd, 4, 0x99, 0x46, 0x66, 0x96); /* 5A 1E 47 58 */

    CALC_S (sa, sb, sc, sd, 5, 0x96, 0x3C, 0x5B, 0xED); /* 58 C6 AE DB */

    CALC_S (sa, sb, sc, sd, 6, 0xED, 0x37, 0x4F, 0xE0); /* DB 68 3D 9E */

    CALC_S (sa, sb, sc, sd, 7, 0xE0, 0xD0, 0x8C, 0x17); /* 9E E5 19 03 */

    CALC_S (se, sf, sg, sh, 8, 0x00, 0x2D, 0x01, 0x2D); /* 01 A4 02 A4 */

    CALC_S (se, sf, sg, sh, 9, 0x2D, 0xA4, 0x44, 0x8A); /* A4 56 A1 55 */

    CALC_S (se, sf, sg, sh, 10, 0x8A, 0xD5, 0xBF, 0xD1); /* 55 82 FC 87 */

    CALC_S (se, sf, sg, sh, 11, 0xD1, 0x7F, 0x3D, 0x99); /* 87 F3 C1 5A */

    CALC_S (se, sf, sg, sh, 12, 0x99, 0x46, 0x66, 0x96); /* 5A 1E 47 58 */

    CALC_S (se, sf, sg, sh, 13, 0x96, 0x3C, 0x5B, 0xED); /* 58 C6 AE DB */

    CALC_S (se, sf, sg, sh, 14, 0xED, 0x37, 0x4F, 0xE0); /* DB 68 3D 9E */

    CALC_S (se, sf, sg, sh, 15, 0xE0, 0xD0, 0x8C, 0x17); /* 9E E5 19 03 */

    if (key_len == 24 || key_len == 32) { /* 192- or 256-bit key */

        /* Calculate the third word of the S vector */

        CALC_S (si, sj, sk, sl, 16, 0x00, 0x2D, 0x01, 0x2D); /* 01 A4 02 A4 */

        CALC_S (si, sj, sk, sl, 17, 0x2D, 0xA4, 0x44, 0x8A); /* A4 56 A1 55 */

        CALC_S (si, sj, sk, sl, 18, 0x8A, 0xD5, 0xBF, 0xD1); /* 55 82 FC 87 */

        CALC_S (si, sj, sk, sl, 19, 0xD1, 0x7F, 0x3D, 0x99); /* 87 F3 C1 5A */

        CALC_S (si, sj, sk, sl, 20, 0x99, 0x46, 0x66, 0x96); /* 5A 1E 47 58 */

        CALC_S (si, sj, sk, sl, 21, 0x96, 0x3C, 0x5B, 0xED); /* 58 C6 AE DB */

        CALC_S (si, sj, sk, sl, 22, 0xED, 0x37, 0x4F, 0xE0); /* DB 68 3D 9E */

        CALC_S (si, sj, sk, sl, 23, 0xE0, 0xD0, 0x8C, 0x17); /* 9E E5 19 03 */

    }

    if (key_len == 32) { /* 256-bit key */

        /* Calculate the fourth word of the S vector */

        CALC_S (sm, sn, so, sp, 24, 0x00, 0x2D, 0x01, 0x2D); /* 01 A4 02 A4 */

        CALC_S (sm, sn, so, sp, 25, 0x2D, 0xA4, 0x44, 0x8A); /* A4 56 A1 55 */

        CALC_S (sm, sn, so, sp, 26, 0x8A, 0xD5, 0xBF, 0xD1); /* 55 82 FC 87 */

        CALC_S (sm, sn, so, sp, 27, 0xD1, 0x7F, 0x3D, 0x99); /* 87 F3 C1 5A */

        CALC_S (sm, sn, so, sp, 28, 0x99, 0x46, 0x66, 0x96); /* 5A 1E 47 58 */

        CALC_S (sm, sn, so, sp, 29, 0x96, 0x3C, 0x5B, 0xED); /* 58 C6 AE DB */

        CALC_S (sm, sn, so, sp, 30, 0xED, 0x37, 0x4F, 0xE0); /* DB 68 3D 9E */

        CALC_S (sm, sn, so, sp, 31, 0xE0, 0xD0, 0x8C, 0x17); /* 9E E5 19 03 */

        /* Compute the S-boxes. */

        for ( i = j = 0, k = 1; i < 256; i++, j += 2, k += 2 ) {

            CALC_SB256_2( i, calc_sb_tbl[j], calc_sb_tbl[k] );

        }

        /* Calculate whitening and round subkeys.  The constants are

         * indices of subkeys, preprocessed through q0 and q1. */

        CALC_K256 (w, 0, 0xA9, 0x75, 0x67, 0xF3);

        CALC_K256 (w, 2, 0xB3, 0xC6, 0xE8, 0xF4);

        CALC_K256 (w, 4, 0x04, 0xDB, 0xFD, 0x7B);

        CALC_K256 (w, 6, 0xA3, 0xFB, 0x76, 0xC8);

        CALC_K256 (k, 0, 0x9A, 0x4A, 0x92, 0xD3);

        CALC_K256 (k, 2, 0x80, 0xE6, 0x78, 0x6B);

        CALC_K256 (k, 4, 0xE4, 0x45, 0xDD, 0x7D);

        CALC_K256 (k, 6, 0xD1, 0xE8, 0x38, 0x4B);

        CALC_K256 (k, 8, 0x0D, 0xD6, 0xC6, 0x32);

        CALC_K256 (k, 10, 0x35, 0xD8, 0x98, 0xFD);

        CALC_K256 (k, 12, 0x18, 0x37, 0xF7, 0x71);

        CALC_K256 (k, 14, 0xEC, 0xF1, 0x6C, 0xE1);

        CALC_K256 (k, 16, 0x43, 0x30, 0x75, 0x0F);

        CALC_K256 (k, 18, 0x37, 0xF8, 0x26, 0x1B);

        CALC_K256 (k, 20, 0xFA, 0x87, 0x13, 0xFA);

        CALC_K256 (k, 22, 0x94, 0x06, 0x48, 0x3F);

        CALC_K256 (k, 24, 0xF2, 0x5E, 0xD0, 0xBA);

        CALC_K256 (k, 26, 0x8B, 0xAE, 0x30, 0x5B);

        CALC_K256 (k, 28, 0x84, 0x8A, 0x54, 0x00);

        CALC_K256 (k, 30, 0xDF, 0xBC, 0x23, 0x9D);

    } else if (key_len == 24) { /* 192-bit key */

        /* Compute the S-boxes. */

        for ( i = j = 0, k = 1; i < 256; i++, j += 2, k += 2 ) {

                CALC_SB192_2( i, calc_sb_tbl[j], calc_sb_tbl[k] );

        }

        /* Calculate whitening and round subkeys.  The constants are

         * indices of subkeys, preprocessed through q0 and q1. */

        CALC_K192 (w, 0, 0xA9, 0x75, 0x67, 0xF3);

        CALC_K192 (w, 2, 0xB3, 0xC6, 0xE8, 0xF4);

        CALC_K192 (w, 4, 0x04, 0xDB, 0xFD, 0x7B);

        CALC_K192 (w, 6, 0xA3, 0xFB, 0x76, 0xC8);

        CALC_K192 (k, 0, 0x9A, 0x4A, 0x92, 0xD3);

        CALC_K192 (k, 2, 0x80, 0xE6, 0x78, 0x6B);

        CALC_K192 (k, 4, 0xE4, 0x45, 0xDD, 0x7D);

        CALC_K192 (k, 6, 0xD1, 0xE8, 0x38, 0x4B);

        CALC_K192 (k, 8, 0x0D, 0xD6, 0xC6, 0x32);

        CALC_K192 (k, 10, 0x35, 0xD8, 0x98, 0xFD);

        CALC_K192 (k, 12, 0x18, 0x37, 0xF7, 0x71);

        CALC_K192 (k, 14, 0xEC, 0xF1, 0x6C, 0xE1);

        CALC_K192 (k, 16, 0x43, 0x30, 0x75, 0x0F);

        CALC_K192 (k, 18, 0x37, 0xF8, 0x26, 0x1B);

        CALC_K192 (k, 20, 0xFA, 0x87, 0x13, 0xFA);

        CALC_K192 (k, 22, 0x94, 0x06, 0x48, 0x3F);

        CALC_K192 (k, 24, 0xF2, 0x5E, 0xD0, 0xBA);

        CALC_K192 (k, 26, 0x8B, 0xAE, 0x30, 0x5B);

        CALC_K192 (k, 28, 0x84, 0x8A, 0x54, 0x00);

        CALC_K192 (k, 30, 0xDF, 0xBC, 0x23, 0x9D);

    } else { /* 128-bit key */

        /* Compute the S-boxes. */

        for ( i = j = 0, k = 1; i < 256; i++, j += 2, k += 2 ) {

            CALC_SB_2( i, calc_sb_tbl[j], calc_sb_tbl[k] );

        }

        /* Calculate whitening and round subkeys.  The constants are

         * indices of subkeys, preprocessed through q0 and q1. */

        CALC_K (w, 0, 0xA9, 0x75, 0x67, 0xF3);

        CALC_K (w, 2, 0xB3, 0xC6, 0xE8, 0xF4);

        CALC_K (w, 4, 0x04, 0xDB, 0xFD, 0x7B);

        CALC_K (w, 6, 0xA3, 0xFB, 0x76, 0xC8);

        CALC_K (k, 0, 0x9A, 0x4A, 0x92, 0xD3);

        CALC_K (k, 2, 0x80, 0xE6, 0x78, 0x6B);

        CALC_K (k, 4, 0xE4, 0x45, 0xDD, 0x7D);

        CALC_K (k, 6, 0xD1, 0xE8, 0x38, 0x4B);

        CALC_K (k, 8, 0x0D, 0xD6, 0xC6, 0x32);

        CALC_K (k, 10, 0x35, 0xD8, 0x98, 0xFD);

        CALC_K (k, 12, 0x18, 0x37, 0xF7, 0x71);

        CALC_K (k, 14, 0xEC, 0xF1, 0x6C, 0xE1);

        CALC_K (k, 16, 0x43, 0x30, 0x75, 0x0F);

        CALC_K (k, 18, 0x37, 0xF8, 0x26, 0x1B);

        CALC_K (k, 20, 0xFA, 0x87, 0x13, 0xFA);

        CALC_K (k, 22, 0x94, 0x06, 0x48, 0x3F);

        CALC_K (k, 24, 0xF2, 0x5E, 0xD0, 0xBA);

        CALC_K (k, 26, 0x8B, 0xAE, 0x30, 0x5B);

        CALC_K (k, 28, 0x84, 0x8A, 0x54, 0x00);

        CALC_K (k, 30, 0xDF, 0xBC, 0x23, 0x9D);

    }

    return 0;

}

/* Macros to compute the g() function in the encryption and decryption

 * rounds.  G1 is the straight g() function; G2 includes the 8-bit

 * rotation for the high 32-bit word. */

#define G1(a) \

     (ctx->s[0][(a) & 0xFF]) ^ (ctx->s[1][((a) >> 8) & 0xFF]) \

   ^ (ctx->s[2][((a) >> 16) & 0xFF]) ^ (ctx->s[3][(a) >> 24])

#define G2(b) \

     (ctx->s[1][(b) & 0xFF]) ^ (ctx->s[2][((b) >> 8) & 0xFF]) \

   ^ (ctx->s[3][((b) >> 16) & 0xFF]) ^ (ctx->s[0][(b) >> 24])

/* Encryption and decryption Feistel rounds.  Each one calls the two g()

 * macros, does the PHT, and performs the XOR and the appropriate bit

 * rotations.  The parameters are the round number (used to select subkeys),

 * and the four 32-bit chunks of the text. */

#define ENCROUND(n, a, b, c, d) \

   x = G1 (a); y = G2 (b); \

   x += y; y += x + ctx->k[2 * (n) + 1]; \

   (c) ^= x + ctx->k[2 * (n)]; \

   (c) = ((c) >> 1) + ((c) << 31); \

   (d) = (((d) << 1)+((d) >> 31)) ^ y

#define DECROUND(n, a, b, c, d) \

   x = G1 (a); y = G2 (b); \

   x += y; y += x; \

   (d) ^= y + ctx->k[2 * (n) + 1]; \

   (d) = ((d) >> 1) + ((d) << 31); \

   (c) = (((c) << 1)+((c) >> 31)); \

   (c) ^= (x + ctx->k[2 * (n)])

/* Encryption and decryption cycles; each one is simply two Feistel rounds

 * with the 32-bit chunks re-ordered to simulate the "swap" */

#define ENCCYCLE(n) \

   ENCROUND (2 * (n), a, b, c, d); \

   ENCROUND (2 * (n) + 1, c, d, a, b)

#define DECCYCLE(n) \

   DECROUND (2 * (n) + 1, c, d, a, b); \

   DECROUND (2 * (n), a, b, c, d)

/* Macros to convert the input and output bytes into 32-bit words,

 * and simultaneously perform the whitening step.  INPACK packs word

 * number n into the variable named by x, using whitening subkey number m.

 * OUTUNPACK unpacks word number n from the variable named by x, using

 * whitening subkey number m. */

#define INPACK(n, x, m) \

   x = in[4 * (n)] ^ (in[4 * (n) + 1] << 8) \

     ^ (in[4 * (n) + 2] << 16) ^ (in[4 * (n) + 3] << 24) ^ ctx->w[m]

#define OUTUNPACK(n, x, m) \

   x ^= ctx->w[m]; \

   out[4 * (n)] = x; out[4 * (n) + 1] = x >> 8; \

   out[4 * (n) + 2] = x >> 16; out[4 * (n) + 3] = x >> 24

/* Encrypt one block.  in and out may be the same. */

int twofish_encrypt (twofish_context *ctx,

                const u8 *in, u8 *out)

{

    /* The four 32-bit chunks of the text. */

    u32 a, b, c, d;

    /* Temporaries used by the round function. */

    u32 x, y;

    /* Input whitening and packing. */

    INPACK (0, a, 0);

    INPACK (1, b, 1);

    INPACK (2, c, 2);

    INPACK (3, d, 3);

    /* Encryption Feistel cycles. */

    ENCCYCLE (0);

    ENCCYCLE (1);

    ENCCYCLE (2);

    ENCCYCLE (3);

    ENCCYCLE (4);

    ENCCYCLE (5);

    ENCCYCLE (6);

    ENCCYCLE (7);

    /* Output whitening and unpacking. */

    OUTUNPACK (0, c, 4);

    OUTUNPACK (1, d, 5);

    OUTUNPACK (2, a, 6);

    OUTUNPACK (3, b, 7);

    return 0;

}

/* Decrypt one block.  in and out may be the same. */

int twofish_decrypt (twofish_context *ctx,

                const u8 *in, u8 *out)

{

    /* The four 32-bit chunks of the text. */

    u32 a, b, c, d;

    /* Temporaries used by the round function. */

    u32 x, y;

    /* Input whitening and packing. */

    INPACK (0, c, 4);

    INPACK (1, d, 5);

    INPACK (2, a, 6);

    INPACK (3, b, 7);

    /* Encryption Feistel cycles. */

    DECCYCLE (7);

    DECCYCLE (6);

    DECCYCLE (5);

    DECCYCLE (4);

    DECCYCLE (3);

    DECCYCLE (2);

    DECCYCLE (1);

    DECCYCLE (0);

    /* Output whitening and unpacking. */

    OUTUNPACK (0, a, 0);