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serpent.c

/*
 * Cryptographic API.
 *
 * Serpent Cipher Algorithm.
 *
 * Copyright (C) 2002 Dag Arne Osvik <osvik@ii.uib.no>
 *               2003 Herbert Valerio Riedel <hvr@gnu.org>
 *
 * Added tnepres support: Ruben Jesus Garcia Hernandez <ruben@ugr.es>, 18.10.2004
 *               Based on code by hvr
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <asm/byteorder.h>
#include <linux/crypto.h>
#include <linux/types.h>

/* Key is padded to the maximum of 256 bits before round key generation.
 * Any key length <= 256 bits (32 bytes) is allowed by the algorithm.
 */

#define SERPENT_MIN_KEY_SIZE          0
#define SERPENT_MAX_KEY_SIZE         32
#define SERPENT_EXPKEY_WORDS        132
#define SERPENT_BLOCK_SIZE           16

#define PHI 0x9e3779b9UL

#define keyiter(a,b,c,d,i,j) \
        b ^= d; b ^= c; b ^= a; b ^= PHI ^ i; b = rol32(b,11); k[j] = b;

#define loadkeys(x0,x1,x2,x3,i) \
      x0=k[i]; x1=k[i+1]; x2=k[i+2]; x3=k[i+3];

#define storekeys(x0,x1,x2,x3,i) \
      k[i]=x0; k[i+1]=x1; k[i+2]=x2; k[i+3]=x3;

#define K(x0,x1,x2,x3,i)                        \
      x3 ^= k[4*(i)+3];        x2 ^= k[4*(i)+2];      \
      x1 ^= k[4*(i)+1];        x0 ^= k[4*(i)+0];

#define LK(x0,x1,x2,x3,x4,i)                    \
                              x0=rol32(x0,13);\
      x2=rol32(x2,3);   x1 ^= x0;   x4  = x0 << 3;    \
      x3 ^= x2;   x1 ^= x2;               \
      x1=rol32(x1,1);   x3 ^= x4;               \
      x3=rol32(x3,7);   x4  = x1;               \
      x0 ^= x1;   x4 <<= 7;   x2 ^= x3;   \
      x0 ^= x3;   x2 ^= x4;   x3 ^= k[4*i+3];   \
      x1 ^= k[4*i+1];   x0=rol32(x0,5);   x2=rol32(x2,22);\
      x0 ^= k[4*i+0];   x2 ^= k[4*i+2];

#define KL(x0,x1,x2,x3,x4,i)                    \
      x0 ^= k[4*i+0];   x1 ^= k[4*i+1];   x2 ^= k[4*i+2];   \
      x3 ^= k[4*i+3];   x0=ror32(x0,5);   x2=ror32(x2,22);\
      x4 =  x1;   x2 ^= x3;   x0 ^= x3;   \
      x4 <<= 7;   x0 ^= x1;   x1=ror32(x1,1);   \
      x2 ^= x4;   x3=ror32(x3,7);   x4 = x0 << 3;     \
      x1 ^= x0;   x3 ^= x4;   x0=ror32(x0,13);\
      x1 ^= x2;   x3 ^= x2;   x2=ror32(x2,3);

#define S0(x0,x1,x2,x3,x4)                      \
                              x4  = x3;   \
      x3 |= x0;   x0 ^= x4;   x4 ^= x2;   \
      x4 =~ x4;   x3 ^= x1;   x1 &= x0;   \
      x1 ^= x4;   x2 ^= x0;   x0 ^= x3;   \
      x4 |= x0;   x0 ^= x2;   x2 &= x1;   \
      x3 ^= x2;   x1 =~ x1;   x2 ^= x4;   \
      x1 ^= x2;

#define S1(x0,x1,x2,x3,x4)                      \
                              x4  = x1;   \
      x1 ^= x0;   x0 ^= x3;   x3 =~ x3;   \
      x4 &= x1;   x0 |= x1;   x3 ^= x2;   \
      x0 ^= x3;   x1 ^= x3;   x3 ^= x4;   \
      x1 |= x4;   x4 ^= x2;   x2 &= x0;   \
      x2 ^= x1;   x1 |= x0;   x0 =~ x0;   \
      x0 ^= x2;   x4 ^= x1;

#define S2(x0,x1,x2,x3,x4)                      \
                              x3 =~ x3;   \
      x1 ^= x0;   x4  = x0;   x0 &= x2;   \
      x0 ^= x3;   x3 |= x4;   x2 ^= x1;   \
      x3 ^= x1;   x1 &= x0;   x0 ^= x2;   \
      x2 &= x3;   x3 |= x1;   x0 =~ x0;   \
      x3 ^= x0;   x4 ^= x0;   x0 ^= x2;   \
      x1 |= x2;

#define S3(x0,x1,x2,x3,x4)                      \
                              x4  = x1;   \
      x1 ^= x3;   x3 |= x0;   x4 &= x0;   \
      x0 ^= x2;   x2 ^= x1;   x1 &= x3;   \
      x2 ^= x3;   x0 |= x4;   x4 ^= x3;   \
      x1 ^= x0;   x0 &= x3;   x3 &= x4;   \
      x3 ^= x2;   x4 |= x1;   x2 &= x1;   \
      x4 ^= x3;   x0 ^= x3;   x3 ^= x2;

#define S4(x0,x1,x2,x3,x4)                      \
                              x4  = x3;   \
      x3 &= x0;   x0 ^= x4;               \
      x3 ^= x2;   x2 |= x4;   x0 ^= x1;   \
      x4 ^= x3;   x2 |= x0;               \
      x2 ^= x1;   x1 &= x0;               \
      x1 ^= x4;   x4 &= x2;   x2 ^= x3;   \
      x4 ^= x0;   x3 |= x1;   x1 =~ x1;   \
      x3 ^= x0;

#define S5(x0,x1,x2,x3,x4)                      \
      x4  = x1;   x1 |= x0;               \
      x2 ^= x1;   x3 =~ x3;   x4 ^= x0;   \
      x0 ^= x2;   x1 &= x4;   x4 |= x3;   \
      x4 ^= x0;   x0 &= x3;   x1 ^= x3;   \
      x3 ^= x2;   x0 ^= x1;   x2 &= x4;   \
      x1 ^= x2;   x2 &= x0;               \
      x3 ^= x2;

#define S6(x0,x1,x2,x3,x4)                      \
                              x4  = x1;   \
      x3 ^= x0;   x1 ^= x2;   x2 ^= x0;   \
      x0 &= x3;   x1 |= x3;   x4 =~ x4;   \
      x0 ^= x1;   x1 ^= x2;               \
      x3 ^= x4;   x4 ^= x0;   x2 &= x0;   \
      x4 ^= x1;   x2 ^= x3;   x3 &= x1;   \
      x3 ^= x0;   x1 ^= x2;

#define S7(x0,x1,x2,x3,x4)                      \
                              x1 =~ x1;   \
      x4  = x1;   x0 =~ x0;   x1 &= x2;   \
      x1 ^= x3;   x3 |= x4;   x4 ^= x2;   \
      x2 ^= x3;   x3 ^= x0;   x0 |= x1;   \
      x2 &= x0;   x0 ^= x4;   x4 ^= x3;   \
      x3 &= x0;   x4 ^= x1;               \
      x2 ^= x4;   x3 ^= x1;   x4 |= x0;   \
      x4 ^= x1;

#define SI0(x0,x1,x2,x3,x4)                     \
                  x4  = x3;   x1 ^= x0;   \
      x3 |= x1;   x4 ^= x1;   x0 =~ x0;   \
      x2 ^= x3;   x3 ^= x0;   x0 &= x1;   \
      x0 ^= x2;   x2 &= x3;   x3 ^= x4;   \
      x2 ^= x3;   x1 ^= x3;   x3 &= x0;   \
      x1 ^= x0;   x0 ^= x2;   x4 ^= x3;

#define SI1(x0,x1,x2,x3,x4)                     \
      x1 ^= x3;   x4  = x0;               \
      x0 ^= x2;   x2 =~ x2;   x4 |= x1;   \
      x4 ^= x3;   x3 &= x1;   x1 ^= x2;   \
      x2 &= x4;   x4 ^= x1;   x1 |= x3;   \
      x3 ^= x0;   x2 ^= x0;   x0 |= x4;   \
      x2 ^= x4;   x1 ^= x0;               \
      x4 ^= x1;

#define SI2(x0,x1,x2,x3,x4)                     \
      x2 ^= x1;   x4  = x3;   x3 =~ x3;   \
      x3 |= x2;   x2 ^= x4;   x4 ^= x0;   \
      x3 ^= x1;   x1 |= x2;   x2 ^= x0;   \
      x1 ^= x4;   x4 |= x3;   x2 ^= x3;   \
      x4 ^= x2;   x2 &= x1;               \
      x2 ^= x3;   x3 ^= x4;   x4 ^= x0;

#define SI3(x0,x1,x2,x3,x4)                     \
                              x2 ^= x1;   \
      x4  = x1;   x1 &= x2;               \
      x1 ^= x0;   x0 |= x4;   x4 ^= x3;   \
      x0 ^= x3;   x3 |= x1;   x1 ^= x2;   \
      x1 ^= x3;   x0 ^= x2;   x2 ^= x3;   \
      x3 &= x1;   x1 ^= x0;   x0 &= x2;   \
      x4 ^= x3;   x3 ^= x0;   x0 ^= x1;

#define SI4(x0,x1,x2,x3,x4)                     \
      x2 ^= x3;   x4  = x0;   x0 &= x1;   \
      x0 ^= x2;   x2 |= x3;   x4 =~ x4;   \
      x1 ^= x0;   x0 ^= x2;   x2 &= x4;   \
      x2 ^= x0;   x0 |= x4;               \
      x0 ^= x3;   x3 &= x2;               \
      x4 ^= x3;   x3 ^= x1;   x1 &= x0;   \
      x4 ^= x1;   x0 ^= x3;

#define SI5(x0,x1,x2,x3,x4)                     \
                  x4  = x1;   x1 |= x2;   \
      x2 ^= x4;   x1 ^= x3;   x3 &= x4;   \
      x2 ^= x3;   x3 |= x0;   x0 =~ x0;   \
      x3 ^= x2;   x2 |= x0;   x4 ^= x1;   \
      x2 ^= x4;   x4 &= x0;   x0 ^= x1;   \
      x1 ^= x3;   x0 &= x2;   x2 ^= x3;   \
      x0 ^= x2;   x2 ^= x4;   x4 ^= x3;

#define SI6(x0,x1,x2,x3,x4)                     \
                  x0 ^= x2;               \
      x4  = x0;   x0 &= x3;   x2 ^= x3;   \
      x0 ^= x2;   x3 ^= x1;   x2 |= x4;   \
      x2 ^= x3;   x3 &= x0;   x0 =~ x0;   \
      x3 ^= x1;   x1 &= x2;   x4 ^= x0;   \
      x3 ^= x4;   x4 ^= x2;   x0 ^= x1;   \
      x2 ^= x0;

#define SI7(x0,x1,x2,x3,x4)                     \
      x4  = x3;   x3 &= x0;   x0 ^= x2;   \
      x2 |= x4;   x4 ^= x1;   x0 =~ x0;   \
      x1 |= x3;   x4 ^= x0;   x0 &= x2;   \
      x0 ^= x1;   x1 &= x2;   x3 ^= x2;   \
      x4 ^= x3;   x2 &= x3;   x3 |= x0;   \
      x1 ^= x4;   x3 ^= x4;   x4 &= x0;   \
      x4 ^= x2;

struct serpent_ctx {
      u32 expkey[SERPENT_EXPKEY_WORDS];
};


static int serpent_setkey(struct crypto_tfm *tfm, const u8 *key,
                    unsigned int keylen)
{
      struct serpent_ctx *ctx = crypto_tfm_ctx(tfm);
      u32 *k = ctx->expkey;
      u8  *k8 = (u8 *)k;
      u32 r0,r1,r2,r3,r4;
      int i;

      /* Copy key, add padding */

      for (i = 0; i < keylen; ++i)
            k8[i] = key[i];
      if (i < SERPENT_MAX_KEY_SIZE)
            k8[i++] = 1;
      while (i < SERPENT_MAX_KEY_SIZE)
            k8[i++] = 0;

      /* Expand key using polynomial */

      r0 = le32_to_cpu(k[3]);
      r1 = le32_to_cpu(k[4]);
      r2 = le32_to_cpu(k[5]);
      r3 = le32_to_cpu(k[6]);
      r4 = le32_to_cpu(k[7]);

      keyiter(le32_to_cpu(k[0]),r0,r4,r2,0,0);
      keyiter(le32_to_cpu(k[1]),r1,r0,r3,1,1);
      keyiter(le32_to_cpu(k[2]),r2,r1,r4,2,2);
      keyiter(le32_to_cpu(k[3]),r3,r2,r0,3,3);
      keyiter(le32_to_cpu(k[4]),r4,r3,r1,4,4);
      keyiter(le32_to_cpu(k[5]),r0,r4,r2,5,5);
      keyiter(le32_to_cpu(k[6]),r1,r0,r3,6,6);
      keyiter(le32_to_cpu(k[7]),r2,r1,r4,7,7);

      keyiter(k[  0],r3,r2,r0,  8,  8); keyiter(k[  1],r4,r3,r1,  9,  9);
      keyiter(k[  2],r0,r4,r2, 10, 10); keyiter(k[  3],r1,r0,r3, 11, 11);
      keyiter(k[  4],r2,r1,r4, 12, 12); keyiter(k[  5],r3,r2,r0, 13, 13);
      keyiter(k[  6],r4,r3,r1, 14, 14); keyiter(k[  7],r0,r4,r2, 15, 15);
      keyiter(k[  8],r1,r0,r3, 16, 16); keyiter(k[  9],r2,r1,r4, 17, 17);
      keyiter(k[ 10],r3,r2,r0, 18, 18); keyiter(k[ 11],r4,r3,r1, 19, 19);
      keyiter(k[ 12],r0,r4,r2, 20, 20); keyiter(k[ 13],r1,r0,r3, 21, 21);
      keyiter(k[ 14],r2,r1,r4, 22, 22); keyiter(k[ 15],r3,r2,r0, 23, 23);
      keyiter(k[ 16],r4,r3,r1, 24, 24); keyiter(k[ 17],r0,r4,r2, 25, 25);
      keyiter(k[ 18],r1,r0,r3, 26, 26); keyiter(k[ 19],r2,r1,r4, 27, 27);
      keyiter(k[ 20],r3,r2,r0, 28, 28); keyiter(k[ 21],r4,r3,r1, 29, 29);
      keyiter(k[ 22],r0,r4,r2, 30, 30); keyiter(k[ 23],r1,r0,r3, 31, 31);

      k += 50;

      keyiter(k[-26],r2,r1,r4, 32,-18); keyiter(k[-25],r3,r2,r0, 33,-17);
      keyiter(k[-24],r4,r3,r1, 34,-16); keyiter(k[-23],r0,r4,r2, 35,-15);
      keyiter(k[-22],r1,r0,r3, 36,-14); keyiter(k[-21],r2,r1,r4, 37,-13);
      keyiter(k[-20],r3,r2,r0, 38,-12); keyiter(k[-19],r4,r3,r1, 39,-11);
      keyiter(k[-18],r0,r4,r2, 40,-10); keyiter(k[-17],r1,r0,r3, 41, -9);
      keyiter(k[-16],r2,r1,r4, 42, -8); keyiter(k[-15],r3,r2,r0, 43, -7);
      keyiter(k[-14],r4,r3,r1, 44, -6); keyiter(k[-13],r0,r4,r2, 45, -5);
      keyiter(k[-12],r1,r0,r3, 46, -4); keyiter(k[-11],r2,r1,r4, 47, -3);
      keyiter(k[-10],r3,r2,r0, 48, -2); keyiter(k[ -9],r4,r3,r1, 49, -1);
      keyiter(k[ -8],r0,r4,r2, 50,  0); keyiter(k[ -7],r1,r0,r3, 51,  1);
      keyiter(k[ -6],r2,r1,r4, 52,  2); keyiter(k[ -5],r3,r2,r0, 53,  3);
      keyiter(k[ -4],r4,r3,r1, 54,  4); keyiter(k[ -3],r0,r4,r2, 55,  5);
      keyiter(k[ -2],r1,r0,r3, 56,  6); keyiter(k[ -1],r2,r1,r4, 57,  7);
      keyiter(k[  0],r3,r2,r0, 58,  8); keyiter(k[  1],r4,r3,r1, 59,  9);
      keyiter(k[  2],r0,r4,r2, 60, 10); keyiter(k[  3],r1,r0,r3, 61, 11);
      keyiter(k[  4],r2,r1,r4, 62, 12); keyiter(k[  5],r3,r2,r0, 63, 13);
      keyiter(k[  6],r4,r3,r1, 64, 14); keyiter(k[  7],r0,r4,r2, 65, 15);
      keyiter(k[  8],r1,r0,r3, 66, 16); keyiter(k[  9],r2,r1,r4, 67, 17);
      keyiter(k[ 10],r3,r2,r0, 68, 18); keyiter(k[ 11],r4,r3,r1, 69, 19);
      keyiter(k[ 12],r0,r4,r2, 70, 20); keyiter(k[ 13],r1,r0,r3, 71, 21);
      keyiter(k[ 14],r2,r1,r4, 72, 22); keyiter(k[ 15],r3,r2,r0, 73, 23);
      keyiter(k[ 16],r4,r3,r1, 74, 24); keyiter(k[ 17],r0,r4,r2, 75, 25);
      keyiter(k[ 18],r1,r0,r3, 76, 26); keyiter(k[ 19],r2,r1,r4, 77, 27);
      keyiter(k[ 20],r3,r2,r0, 78, 28); keyiter(k[ 21],r4,r3,r1, 79, 29);
      keyiter(k[ 22],r0,r4,r2, 80, 30); keyiter(k[ 23],r1,r0,r3, 81, 31);

      k += 50;

      keyiter(k[-26],r2,r1,r4, 82,-18); keyiter(k[-25],r3,r2,r0, 83,-17);
      keyiter(k[-24],r4,r3,r1, 84,-16); keyiter(k[-23],r0,r4,r2, 85,-15);
      keyiter(k[-22],r1,r0,r3, 86,-14); keyiter(k[-21],r2,r1,r4, 87,-13);
      keyiter(k[-20],r3,r2,r0, 88,-12); keyiter(k[-19],r4,r3,r1, 89,-11);
      keyiter(k[-18],r0,r4,r2, 90,-10); keyiter(k[-17],r1,r0,r3, 91, -9);
      keyiter(k[-16],r2,r1,r4, 92, -8); keyiter(k[-15],r3,r2,r0, 93, -7);
      keyiter(k[-14],r4,r3,r1, 94, -6); keyiter(k[-13],r0,r4,r2, 95, -5);
      keyiter(k[-12],r1,r0,r3, 96, -4); keyiter(k[-11],r2,r1,r4, 97, -3);
      keyiter(k[-10],r3,r2,r0, 98, -2); keyiter(k[ -9],r4,r3,r1, 99, -1);
      keyiter(k[ -8],r0,r4,r2,100,  0); keyiter(k[ -7],r1,r0,r3,101,  1);
      keyiter(k[ -6],r2,r1,r4,102,  2); keyiter(k[ -5],r3,r2,r0,103,  3);
      keyiter(k[ -4],r4,r3,r1,104,  4); keyiter(k[ -3],r0,r4,r2,105,  5);
      keyiter(k[ -2],r1,r0,r3,106,  6); keyiter(k[ -1],r2,r1,r4,107,  7);
      keyiter(k[  0],r3,r2,r0,108,  8); keyiter(k[  1],r4,r3,r1,109,  9);
      keyiter(k[  2],r0,r4,r2,110, 10); keyiter(k[  3],r1,r0,r3,111, 11);
      keyiter(k[  4],r2,r1,r4,112, 12); keyiter(k[  5],r3,r2,r0,113, 13);
      keyiter(k[  6],r4,r3,r1,114, 14); keyiter(k[  7],r0,r4,r2,115, 15);
      keyiter(k[  8],r1,r0,r3,116, 16); keyiter(k[  9],r2,r1,r4,117, 17);
      keyiter(k[ 10],r3,r2,r0,118, 18); keyiter(k[ 11],r4,r3,r1,119, 19);
      keyiter(k[ 12],r0,r4,r2,120, 20); keyiter(k[ 13],r1,r0,r3,121, 21);
      keyiter(k[ 14],r2,r1,r4,122, 22); keyiter(k[ 15],r3,r2,r0,123, 23);
      keyiter(k[ 16],r4,r3,r1,124, 24); keyiter(k[ 17],r0,r4,r2,125, 25);
      keyiter(k[ 18],r1,r0,r3,126, 26); keyiter(k[ 19],r2,r1,r4,127, 27);
      keyiter(k[ 20],r3,r2,r0,128, 28); keyiter(k[ 21],r4,r3,r1,129, 29);
      keyiter(k[ 22],r0,r4,r2,130, 30); keyiter(k[ 23],r1,r0,r3,131, 31);

      /* Apply S-boxes */

      S3(r3,r4,r0,r1,r2); storekeys(r1,r2,r4,r3, 28); loadkeys(r1,r2,r4,r3, 24);
      S4(r1,r2,r4,r3,r0); storekeys(r2,r4,r3,r0, 24); loadkeys(r2,r4,r3,r0, 20);
      S5(r2,r4,r3,r0,r1); storekeys(r1,r2,r4,r0, 20); loadkeys(r1,r2,r4,r0, 16);
      S6(r1,r2,r4,r0,r3); storekeys(r4,r3,r2,r0, 16); loadkeys(r4,r3,r2,r0, 12);
      S7(r4,r3,r2,r0,r1); storekeys(r1,r2,r0,r4, 12); loadkeys(r1,r2,r0,r4,  8);
      S0(r1,r2,r0,r4,r3); storekeys(r0,r2,r4,r1,  8); loadkeys(r0,r2,r4,r1,  4);
      S1(r0,r2,r4,r1,r3); storekeys(r3,r4,r1,r0,  4); loadkeys(r3,r4,r1,r0,  0);
      S2(r3,r4,r1,r0,r2); storekeys(r2,r4,r3,r0,  0); loadkeys(r2,r4,r3,r0, -4);
      S3(r2,r4,r3,r0,r1); storekeys(r0,r1,r4,r2, -4); loadkeys(r0,r1,r4,r2, -8);
      S4(r0,r1,r4,r2,r3); storekeys(r1,r4,r2,r3, -8); loadkeys(r1,r4,r2,r3,-12);
      S5(r1,r4,r2,r3,r0); storekeys(r0,r1,r4,r3,-12); loadkeys(r0,r1,r4,r3,-16);
      S6(r0,r1,r4,r3,r2); storekeys(r4,r2,r1,r3,-16); loadkeys(r4,r2,r1,r3,-20);
      S7(r4,r2,r1,r3,r0); storekeys(r0,r1,r3,r4,-20); loadkeys(r0,r1,r3,r4,-24);
      S0(r0,r1,r3,r4,r2); storekeys(r3,r1,r4,r0,-24); loadkeys(r3,r1,r4,r0,-28);
      k -= 50;
      S1(r3,r1,r4,r0,r2); storekeys(r2,r4,r0,r3, 22); loadkeys(r2,r4,r0,r3, 18);
      S2(r2,r4,r0,r3,r1); storekeys(r1,r4,r2,r3, 18); loadkeys(r1,r4,r2,r3, 14);
      S3(r1,r4,r2,r3,r0); storekeys(r3,r0,r4,r1, 14); loadkeys(r3,r0,r4,r1, 10);
      S4(r3,r0,r4,r1,r2); storekeys(r0,r4,r1,r2, 10); loadkeys(r0,r4,r1,r2,  6);
      S5(r0,r4,r1,r2,r3); storekeys(r3,r0,r4,r2,  6); loadkeys(r3,r0,r4,r2,  2);
      S6(r3,r0,r4,r2,r1); storekeys(r4,r1,r0,r2,  2); loadkeys(r4,r1,r0,r2, -2);
      S7(r4,r1,r0,r2,r3); storekeys(r3,r0,r2,r4, -2); loadkeys(r3,r0,r2,r4, -6);
      S0(r3,r0,r2,r4,r1); storekeys(r2,r0,r4,r3, -6); loadkeys(r2,r0,r4,r3,-10);
      S1(r2,r0,r4,r3,r1); storekeys(r1,r4,r3,r2,-10); loadkeys(r1,r4,r3,r2,-14);
      S2(r1,r4,r3,r2,r0); storekeys(r0,r4,r1,r2,-14); loadkeys(r0,r4,r1,r2,-18);
      S3(r0,r4,r1,r2,r3); storekeys(r2,r3,r4,r0,-18); loadkeys(r2,r3,r4,r0,-22);
      k -= 50;
      S4(r2,r3,r4,r0,r1); storekeys(r3,r4,r0,r1, 28); loadkeys(r3,r4,r0,r1, 24);
      S5(r3,r4,r0,r1,r2); storekeys(r2,r3,r4,r1, 24); loadkeys(r2,r3,r4,r1, 20);
      S6(r2,r3,r4,r1,r0); storekeys(r4,r0,r3,r1, 20); loadkeys(r4,r0,r3,r1, 16);
      S7(r4,r0,r3,r1,r2); storekeys(r2,r3,r1,r4, 16); loadkeys(r2,r3,r1,r4, 12);
      S0(r2,r3,r1,r4,r0); storekeys(r1,r3,r4,r2, 12); loadkeys(r1,r3,r4,r2,  8);
      S1(r1,r3,r4,r2,r0); storekeys(r0,r4,r2,r1,  8); loadkeys(r0,r4,r2,r1,  4);
      S2(r0,r4,r2,r1,r3); storekeys(r3,r4,r0,r1,  4); loadkeys(r3,r4,r0,r1,  0);
      S3(r3,r4,r0,r1,r2); storekeys(r1,r2,r4,r3,  0);

      return 0;
}

static void serpent_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
{
      struct serpent_ctx *ctx = crypto_tfm_ctx(tfm);
      const u32
            *k = ctx->expkey;
      const __le32 *s = (const __le32 *)src;
      __le32      *d = (__le32 *)dst;
      u32   r0, r1, r2, r3, r4;

/*
 * Note: The conversions between u8* and u32* might cause trouble
 * on architectures with stricter alignment rules than x86
 */

      r0 = le32_to_cpu(s[0]);
      r1 = le32_to_cpu(s[1]);
      r2 = le32_to_cpu(s[2]);
      r3 = le32_to_cpu(s[3]);

                         K(r0,r1,r2,r3,0);
      S0(r0,r1,r2,r3,r4);     LK(r2,r1,r3,r0,r4,1);
      S1(r2,r1,r3,r0,r4);     LK(r4,r3,r0,r2,r1,2);
      S2(r4,r3,r0,r2,r1);     LK(r1,r3,r4,r2,r0,3);
      S3(r1,r3,r4,r2,r0);     LK(r2,r0,r3,r1,r4,4);
      S4(r2,r0,r3,r1,r4);     LK(r0,r3,r1,r4,r2,5);
      S5(r0,r3,r1,r4,r2);     LK(r2,r0,r3,r4,r1,6);
      S6(r2,r0,r3,r4,r1);     LK(r3,r1,r0,r4,r2,7);
      S7(r3,r1,r0,r4,r2);     LK(r2,r0,r4,r3,r1,8);
      S0(r2,r0,r4,r3,r1);     LK(r4,r0,r3,r2,r1,9);
      S1(r4,r0,r3,r2,r1);     LK(r1,r3,r2,r4,r0,10);
      S2(r1,r3,r2,r4,r0);     LK(r0,r3,r1,r4,r2,11);
      S3(r0,r3,r1,r4,r2);     LK(r4,r2,r3,r0,r1,12);
      S4(r4,r2,r3,r0,r1);     LK(r2,r3,r0,r1,r4,13);
      S5(r2,r3,r0,r1,r4);     LK(r4,r2,r3,r1,r0,14);
      S6(r4,r2,r3,r1,r0);     LK(r3,r0,r2,r1,r4,15);
      S7(r3,r0,r2,r1,r4);     LK(r4,r2,r1,r3,r0,16);
      S0(r4,r2,r1,r3,r0);     LK(r1,r2,r3,r4,r0,17);
      S1(r1,r2,r3,r4,r0);     LK(r0,r3,r4,r1,r2,18);
      S2(r0,r3,r4,r1,r2);     LK(r2,r3,r0,r1,r4,19);
      S3(r2,r3,r0,r1,r4);     LK(r1,r4,r3,r2,r0,20);
      S4(r1,r4,r3,r2,r0);     LK(r4,r3,r2,r0,r1,21);
      S5(r4,r3,r2,r0,r1);     LK(r1,r4,r3,r0,r2,22);
      S6(r1,r4,r3,r0,r2);     LK(r3,r2,r4,r0,r1,23);
      S7(r3,r2,r4,r0,r1);     LK(r1,r4,r0,r3,r2,24);
      S0(r1,r4,r0,r3,r2);     LK(r0,r4,r3,r1,r2,25);
      S1(r0,r4,r3,r1,r2);     LK(r2,r3,r1,r0,r4,26);
      S2(r2,r3,r1,r0,r4);     LK(r4,r3,r2,r0,r1,27);
      S3(r4,r3,r2,r0,r1);     LK(r0,r1,r3,r4,r2,28);
      S4(r0,r1,r3,r4,r2);     LK(r1,r3,r4,r2,r0,29);
      S5(r1,r3,r4,r2,r0);     LK(r0,r1,r3,r2,r4,30);
      S6(r0,r1,r3,r2,r4);     LK(r3,r4,r1,r2,r0,31);
      S7(r3,r4,r1,r2,r0);      K(r0,r1,r2,r3,32);

      d[0] = cpu_to_le32(r0);
      d[1] = cpu_to_le32(r1);
      d[2] = cpu_to_le32(r2);
      d[3] = cpu_to_le32(r3);
}

static void serpent_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
{
      struct serpent_ctx *ctx = crypto_tfm_ctx(tfm);
      const u32
            *k = ((struct serpent_ctx *)ctx)->expkey;
      const __le32 *s = (const __le32 *)src;
      __le32      *d = (__le32 *)dst;
      u32   r0, r1, r2, r3, r4;

      r0 = le32_to_cpu(s[0]);
      r1 = le32_to_cpu(s[1]);
      r2 = le32_to_cpu(s[2]);
      r3 = le32_to_cpu(s[3]);

                        K(r0,r1,r2,r3,32);
      SI7(r0,r1,r2,r3,r4);    KL(r1,r3,r0,r4,r2,31);
      SI6(r1,r3,r0,r4,r2);    KL(r0,r2,r4,r1,r3,30);
      SI5(r0,r2,r4,r1,r3);    KL(r2,r3,r0,r4,r1,29);
      SI4(r2,r3,r0,r4,r1);    KL(r2,r0,r1,r4,r3,28);
      SI3(r2,r0,r1,r4,r3);    KL(r1,r2,r3,r4,r0,27);
      SI2(r1,r2,r3,r4,r0);    KL(r2,r0,r4,r3,r1,26);
      SI1(r2,r0,r4,r3,r1);    KL(r1,r0,r4,r3,r2,25);
      SI0(r1,r0,r4,r3,r2);    KL(r4,r2,r0,r1,r3,24);
      SI7(r4,r2,r0,r1,r3);    KL(r2,r1,r4,r3,r0,23);
      SI6(r2,r1,r4,r3,r0);    KL(r4,r0,r3,r2,r1,22);
      SI5(r4,r0,r3,r2,r1);    KL(r0,r1,r4,r3,r2,21);
      SI4(r0,r1,r4,r3,r2);    KL(r0,r4,r2,r3,r1,20);
      SI3(r0,r4,r2,r3,r1);    KL(r2,r0,r1,r3,r4,19);
      SI2(r2,r0,r1,r3,r4);    KL(r0,r4,r3,r1,r2,18);
      SI1(r0,r4,r3,r1,r2);    KL(r2,r4,r3,r1,r0,17);
      SI0(r2,r4,r3,r1,r0);    KL(r3,r0,r4,r2,r1,16);
      SI7(r3,r0,r4,r2,r1);    KL(r0,r2,r3,r1,r4,15);
      SI6(r0,r2,r3,r1,r4);    KL(r3,r4,r1,r0,r2,14);
      SI5(r3,r4,r1,r0,r2);    KL(r4,r2,r3,r1,r0,13);
      SI4(r4,r2,r3,r1,r0);    KL(r4,r3,r0,r1,r2,12);
      SI3(r4,r3,r0,r1,r2);    KL(r0,r4,r2,r1,r3,11);
      SI2(r0,r4,r2,r1,r3);    KL(r4,r3,r1,r2,r0,10);
      SI1(r4,r3,r1,r2,r0);    KL(r0,r3,r1,r2,r4,9);
      SI0(r0,r3,r1,r2,r4);    KL(r1,r4,r3,r0,r2,8);
      SI7(r1,r4,r3,r0,r2);    KL(r4,r0,r1,r2,r3,7);
      SI6(r4,r0,r1,r2,r3);    KL(r1,r3,r2,r4,r0,6);
      SI5(r1,r3,r2,r4,r0);    KL(r3,r0,r1,r2,r4,5);
      SI4(r3,r0,r1,r2,r4);    KL(r3,r1,r4,r2,r0,4);
      SI3(r3,r1,r4,r2,r0);    KL(r4,r3,r0,r2,r1,3);
      SI2(r4,r3,r0,r2,r1);    KL(r3,r1,r2,r0,r4,2);
      SI1(r3,r1,r2,r0,r4);    KL(r4,r1,r2,r0,r3,1);
      SI0(r4,r1,r2,r0,r3);    K(r2,r3,r1,r4,0);

      d[0] = cpu_to_le32(r2);
      d[1] = cpu_to_le32(r3);
      d[2] = cpu_to_le32(r1);
      d[3] = cpu_to_le32(r4);
}

static struct crypto_alg serpent_alg = {
      .cra_name         =     "serpent",
      .cra_flags        =     CRYPTO_ALG_TYPE_CIPHER,
      .cra_blocksize          =     SERPENT_BLOCK_SIZE,
      .cra_ctxsize            =     sizeof(struct serpent_ctx),
      .cra_alignmask          =     3,
      .cra_module       =     THIS_MODULE,
      .cra_list         =     LIST_HEAD_INIT(serpent_alg.cra_list),
      .cra_u                  =     { .cipher = {
      .cia_min_keysize  =     SERPENT_MIN_KEY_SIZE,
      .cia_max_keysize  =     SERPENT_MAX_KEY_SIZE,
      .cia_setkey             =     serpent_setkey,
      .cia_encrypt            =     serpent_encrypt,
      .cia_decrypt            =     serpent_decrypt } }
};

static int tnepres_setkey(struct crypto_tfm *tfm, const u8 *key,
                    unsigned int keylen)
{
      u8 rev_key[SERPENT_MAX_KEY_SIZE];
      int i;

      for (i = 0; i < keylen; ++i)
            rev_key[keylen - i - 1] = key[i];
 
      return serpent_setkey(tfm, rev_key, keylen);
}

static void tnepres_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
{
      const u32 * const s = (const u32 * const)src;
      u32 * const d = (u32 * const)dst;

      u32 rs[4], rd[4];

      rs[0] = swab32(s[3]);
      rs[1] = swab32(s[2]);
      rs[2] = swab32(s[1]);
      rs[3] = swab32(s[0]);

      serpent_encrypt(tfm, (u8 *)rd, (u8 *)rs);

      d[0] = swab32(rd[3]);
      d[1] = swab32(rd[2]);
      d[2] = swab32(rd[1]);
      d[3] = swab32(rd[0]);
}

static void tnepres_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
{
      const u32 * const s = (const u32 * const)src;
      u32 * const d = (u32 * const)dst;

      u32 rs[4], rd[4];

      rs[0] = swab32(s[3]);
      rs[1] = swab32(s[2]);
      rs[2] = swab32(s[1]);
      rs[3] = swab32(s[0]);

      serpent_decrypt(tfm, (u8 *)rd, (u8 *)rs);

      d[0] = swab32(rd[3]);
      d[1] = swab32(rd[2]);
      d[2] = swab32(rd[1]);
      d[3] = swab32(rd[0]);
}

static struct crypto_alg tnepres_alg = {
      .cra_name         =     "tnepres",
      .cra_flags        =     CRYPTO_ALG_TYPE_CIPHER,
      .cra_blocksize          =     SERPENT_BLOCK_SIZE,
      .cra_ctxsize            =     sizeof(struct serpent_ctx),
      .cra_alignmask          =     3,
      .cra_module       =     THIS_MODULE,
      .cra_list         =     LIST_HEAD_INIT(serpent_alg.cra_list),
      .cra_u                  =     { .cipher = {
      .cia_min_keysize  =     SERPENT_MIN_KEY_SIZE,
      .cia_max_keysize  =     SERPENT_MAX_KEY_SIZE,
      .cia_setkey             =     tnepres_setkey,
      .cia_encrypt            =     tnepres_encrypt,
      .cia_decrypt            =     tnepres_decrypt } }
};

static int __init init(void)
{
      int ret = crypto_register_alg(&serpent_alg);

      if (ret)
            return ret;

      ret = crypto_register_alg(&tnepres_alg);

      if (ret)
            crypto_unregister_alg(&serpent_alg);

      return ret;
}

static void __exit fini(void)
{
      crypto_unregister_alg(&tnepres_alg);
      crypto_unregister_alg(&serpent_alg);
}

module_init(init);
module_exit(fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Serpent and tnepres (kerneli compatible serpent reversed) Cipher Algorithm");
MODULE_AUTHOR("Dag Arne Osvik <osvik@ii.uib.no>");
MODULE_ALIAS("tnepres");

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