# Release 4.8 crypto/serpent_generic.c

Directory: crypto
```/*
* Cryptographic API.
*
* Serpent Cipher Algorithm.
*
* Copyright (C) 2002 Dag Arne Osvik <osvik@ii.uib.no>
*               2003 Herbert Valerio Riedel <hvr@gnu.org>
*
*              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
* 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>
#include <crypto/serpent.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 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 store_and_load_keys(x0, x1, x2, x3, s, l) \
({ storekeys(x0, x1, x2, x3, s); loadkeys(x0, x1, x2, x3, l); })

#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;                                       \
})

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

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); store_and_load_keys(r1, r2, r4, r3, 28, 24);
S4(r1, r2, r4, r3, r0); store_and_load_keys(r2, r4, r3, r0, 24, 20```