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/*******************************************************************************
*
* FILE: safer.c
*
* DESCRIPTION: block-cipher algorithm SAFER (Secure And Fast Encryption
* Routine) in its four versions: SAFER K-64, SAFER K-128,
* SAFER SK-64 and SAFER SK-128.
*
* AUTHOR: Richard De Moliner (demoliner@isi.ee.ethz.ch)
* Signal and Information Processing Laboratory
* Swiss Federal Institute of Technology
* CH-8092 Zuerich, Switzerland
*
* DATE: September 9, 1995
*
* CHANGE HISTORY:
*
*******************************************************************************/
/******************* External Headers *****************************************/
/******************* Local Headers ********************************************/
#include "safer.h"
/******************* Constants ************************************************/
#define TAB_LEN 256
/******************* Assertions ***********************************************/
/******************* Macros ***************************************************/
#define ROL(x, n) ((unsigned char)((unsigned int)(x) << (n)\
|(unsigned int)((x) & 0xFF) >> (8 - (n))))
#define EXP(x) exp_tab[(x) & 0xFF]
#define LOG(x) log_tab[(x) & 0xFF]
#define PHT(x, y) { y += x; x += y; }
#define IPHT(x, y) { x -= y; y -= x; }
/******************* Types ****************************************************/
static unsigned char exp_tab[TAB_LEN];
static unsigned char log_tab[TAB_LEN];
/******************* Module Data **********************************************/
/******************* Functions ************************************************/
/******************************************************************************/
#ifndef NOT_ANSI_C
void Safer_Init_Module(void)
#else
Safer_Init_Module()
#endif
{ unsigned int i, exp;
exp = 1;
for (i = 0; i < TAB_LEN; i++)
{
exp_tab[i] = (unsigned char)(exp & 0xFF);
log_tab[exp_tab[i]] = (unsigned char)i;
exp = exp * 45 % 257;
}
} /* Safer_Init_Module */
/******************************************************************************/
#ifndef NOT_ANSI_C
void Safer_Expand_Userkey(safer_block_t userkey_1,
safer_block_t userkey_2,
unsigned int nof_rounds,
int strengthened,
safer_key_t key)
#else
Safer_Expand_Userkey(userkey_1, userkey_2, nof_rounds, strengthened, key)
safer_block_t userkey_1;
safer_block_t userkey_2;
unsigned int nof_rounds;
int strengthened;
safer_key_t key;
#endif
{ unsigned int i, j;
unsigned char ka[SAFER_BLOCK_LEN + 1];
unsigned char kb[SAFER_BLOCK_LEN + 1];
if (SAFER_MAX_NOF_ROUNDS < nof_rounds)
nof_rounds = SAFER_MAX_NOF_ROUNDS;
*key++ = (unsigned char)nof_rounds;
ka[SAFER_BLOCK_LEN] = 0;
kb[SAFER_BLOCK_LEN] = 0;
for (j = 0; j < SAFER_BLOCK_LEN; j++)
{
ka[SAFER_BLOCK_LEN] ^= ka[j] = ROL(userkey_1[j], 5);
kb[SAFER_BLOCK_LEN] ^= kb[j] = *key++ = userkey_2[j];
}
for (i = 1; i <= nof_rounds; i++)
{
for (j = 0; j < SAFER_BLOCK_LEN + 1; j++)
{
ka[j] = ROL(ka[j], 6);
kb[j] = ROL(kb[j], 6);
}
for (j = 0; j < SAFER_BLOCK_LEN; j++)
if (strengthened)
*key++ = (ka[(j + 2 * i - 1) % (SAFER_BLOCK_LEN + 1)]
+ exp_tab[exp_tab[18 * i + j + 1]]) & 0xFF;
else
*key++ = (ka[j] + exp_tab[exp_tab[18 * i + j + 1]]) & 0xFF;
for (j = 0; j < SAFER_BLOCK_LEN; j++)
if (strengthened)
*key++ = (kb[(j + 2 * i) % (SAFER_BLOCK_LEN + 1)]
+ exp_tab[exp_tab[18 * i + j + 10]]) & 0xFF;
else
*key++ = (kb[j] + exp_tab[exp_tab[18 * i + j + 10]]) & 0xFF;
}
for (j = 0; j < SAFER_BLOCK_LEN + 1; j++)
ka[j] = kb[j] = 0;
} /* Safer_Expand_Userkey */
/******************************************************************************/
#ifndef NOT_ANSI_C
void Safer_Encrypt_Block(safer_block_t block_in, safer_key_t key,
safer_block_t block_out)
#else
Safer_Encrypt_Block(block_in, key, block_out)
safer_block_t block_in;
safer_key_t key;
safer_block_t block_out;
#endif
{ unsigned char a, b, c, d, e, f, g, h, t;
unsigned int round;
a = block_in[0]; b = block_in[1]; c = block_in[2]; d = block_in[3];
e = block_in[4]; f = block_in[5]; g = block_in[6]; h = block_in[7];
if (SAFER_MAX_NOF_ROUNDS < (round = *key)) round = SAFER_MAX_NOF_ROUNDS;
while(round--)
{
a ^= *++key; b += *++key; c += *++key; d ^= *++key;
e ^= *++key; f += *++key; g += *++key; h ^= *++key;
a = EXP(a) + *++key; b = LOG(b) ^ *++key;
c = LOG(c) ^ *++key; d = EXP(d) + *++key;
e = EXP(e) + *++key; f = LOG(f) ^ *++key;
g = LOG(g) ^ *++key; h = EXP(h) + *++key;
PHT(a, b); PHT(c, d); PHT(e, f); PHT(g, h);
PHT(a, c); PHT(e, g); PHT(b, d); PHT(f, h);
PHT(a, e); PHT(b, f); PHT(c, g); PHT(d, h);
t = b; b = e; e = c; c = t; t = d; d = f; f = g; g = t;
}
a ^= *++key; b += *++key; c += *++key; d ^= *++key;
e ^= *++key; f += *++key; g += *++key; h ^= *++key;
block_out[0] = a & 0xFF; block_out[1] = b & 0xFF;
block_out[2] = c & 0xFF; block_out[3] = d & 0xFF;
block_out[4] = e & 0xFF; block_out[5] = f & 0xFF;
block_out[6] = g & 0xFF; block_out[7] = h & 0xFF;
} /* Safer_Encrypt_Block */
/******************************************************************************/
#ifndef NOT_ANSI_C
void Safer_Decrypt_Block(safer_block_t block_in, safer_key_t key,
safer_block_t block_out)
#else
Safer_Decrypt_Block(block_in, key, block_out)
safer_block_t block_in;
safer_key_t key;
safer_block_t block_out;
#endif
{ unsigned char a, b, c, d, e, f, g, h, t;
unsigned int round;
a = block_in[0]; b = block_in[1]; c = block_in[2]; d = block_in[3];
e = block_in[4]; f = block_in[5]; g = block_in[6]; h = block_in[7];
if (SAFER_MAX_NOF_ROUNDS < (round = *key)) round = SAFER_MAX_NOF_ROUNDS;
key += SAFER_BLOCK_LEN * (1 + 2 * round);
h ^= *key; g -= *--key; f -= *--key; e ^= *--key;
d ^= *--key; c -= *--key; b -= *--key; a ^= *--key;
while (round--)
{
t = e; e = b; b = c; c = t; t = f; f = d; d = g; g = t;
IPHT(a, e); IPHT(b, f); IPHT(c, g); IPHT(d, h);
IPHT(a, c); IPHT(e, g); IPHT(b, d); IPHT(f, h);
IPHT(a, b); IPHT(c, d); IPHT(e, f); IPHT(g, h);
h -= *--key; g ^= *--key; f ^= *--key; e -= *--key;
d -= *--key; c ^= *--key; b ^= *--key; a -= *--key;
h = LOG(h) ^ *--key; g = EXP(g) - *--key;
f = EXP(f) - *--key; e = LOG(e) ^ *--key;
d = LOG(d) ^ *--key; c = EXP(c) - *--key;
b = EXP(b) - *--key; a = LOG(a) ^ *--key;
}
block_out[0] = a & 0xFF; block_out[1] = b & 0xFF;
block_out[2] = c & 0xFF; block_out[3] = d & 0xFF;
block_out[4] = e & 0xFF; block_out[5] = f & 0xFF;
block_out[6] = g & 0xFF; block_out[7] = h & 0xFF;
} /* Safer_Decrypt_Block */
/******************************************************************************/
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