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incubator-nuttx/crypto/cast.c

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/****************************************************************************
* crypto/cast.c
* $OpenBSD: cast.c,v 1.4 2012/04/25 04:12:27 matthew Exp $
*
* CAST-128 in C
* Written by Steve Reid <sreid@sea-to-sky.net>
* 100% Public Domain - no warranty
* Released 1997.10.11
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <sys/types.h>
#include <sys/systm.h>
#include <crypto/cast.h>
#include "castsb.h"
/* Macros to access 8-bit bytes out of a 32-bit word */
#define UINT8_TA(x) ( (uint8_t) (x>>24) )
#define UINT8_TB(x) ( (uint8_t) ((x>>16)&255) )
#define UINT8_TC(x) ( (uint8_t) ((x>>8)&255) )
#define UINT8_TD(x) ( (uint8_t) ((x)&255) )
/* Circular left shift */
#define ROL(x, n) ( ((x)<<(n)) | ((x)>>(32-(n))) )
/* CAST-128 uses three different round functions */
#define F1(l, r, i) \
t = ROL(key->xkey[i] + r, key->xkey[i+16]); \
l ^= ((cast_sbox1[UINT8_TA(t)] ^ cast_sbox2[UINT8_TB(t)]) - \
cast_sbox3[UINT8_TC(t)]) + cast_sbox4[UINT8_TD(t)];
#define F2(l, r, i) \
t = ROL(key->xkey[i] ^ r, key->xkey[i+16]); \
l ^= ((cast_sbox1[UINT8_TA(t)] - cast_sbox2[UINT8_TB(t)]) + \
cast_sbox3[UINT8_TC(t)]) ^ cast_sbox4[UINT8_TD(t)];
#define F3(l, r, i) \
t = ROL(key->xkey[i] - r, key->xkey[i+16]); \
l ^= ((cast_sbox1[UINT8_TA(t)] + cast_sbox2[UINT8_TB(t)]) ^ \
cast_sbox3[UINT8_TC(t)]) - cast_sbox4[UINT8_TD(t)];
/****************************************************************************
* Public Functions
****************************************************************************/
/* Encryption Function */
void cast_encrypt(FAR cast_key *key,
FAR uint8_t *inblock,
FAR uint8_t *outblock)
{
uint32_t t;
uint32_t l;
uint32_t r;
/* Get inblock into l,r */
l = ((uint32_t)inblock[0] << 24) |
((uint32_t)inblock[1] << 16) |
((uint32_t)inblock[2] << 8) |
(uint32_t)inblock[3];
r = ((uint32_t)inblock[4] << 24) |
((uint32_t)inblock[5] << 16) |
((uint32_t)inblock[6] << 8) |
(uint32_t)inblock[7];
/* Do the work */
F1(l, r, 0);
F2(r, l, 1);
F3(l, r, 2);
F1(r, l, 3);
F2(l, r, 4);
F3(r, l, 5);
F1(l, r, 6);
F2(r, l, 7);
F3(l, r, 8);
F1(r, l, 9);
F2(l, r, 10);
F3(r, l, 11);
/* Only do full 16 rounds if key length > 80 bits */
if (key->rounds > 12)
{
F1(l, r, 12);
F2(r, l, 13);
F3(l, r, 14);
F1(r, l, 15);
}
/* Put l,r into outblock */
outblock[0] = UINT8_TA(r);
outblock[1] = UINT8_TB(r);
outblock[2] = UINT8_TC(r);
outblock[3] = UINT8_TD(r);
outblock[4] = UINT8_TA(l);
outblock[5] = UINT8_TB(l);
outblock[6] = UINT8_TC(l);
outblock[7] = UINT8_TD(l);
/* Wipe clean */
t = l = r = 0;
}
/* Decryption Function */
void cast_decrypt(FAR cast_key *key,
FAR uint8_t *inblock,
FAR uint8_t *outblock)
{
uint32_t t;
uint32_t l;
uint32_t r;
/* Get inblock into l,r */
r = ((uint32_t)inblock[0] << 24) |
((uint32_t)inblock[1] << 16) |
((uint32_t)inblock[2] << 8) |
(uint32_t)inblock[3];
l = ((uint32_t)inblock[4] << 24) |
((uint32_t)inblock[5] << 16) |
((uint32_t)inblock[6] << 8) |
(uint32_t)inblock[7];
/* Do the work */
/* Only do full 16 rounds if key length > 80 bits */
if (key->rounds > 12)
{
F1(r, l, 15);
F3(l, r, 14);
F2(r, l, 13);
F1(l, r, 12);
}
F3(r, l, 11);
F2(l, r, 10);
F1(r, l, 9);
F3(l, r, 8);
F2(r, l, 7);
F1(l, r, 6);
F3(r, l, 5);
F2(l, r, 4);
F1(r, l, 3);
F3(l, r, 2);
F2(r, l, 1);
F1(l, r, 0);
/* Put l,r into outblock */
outblock[0] = UINT8_TA(l);
outblock[1] = UINT8_TB(l);
outblock[2] = UINT8_TC(l);
outblock[3] = UINT8_TD(l);
outblock[4] = UINT8_TA(r);
outblock[5] = UINT8_TB(r);
outblock[6] = UINT8_TC(r);
outblock[7] = UINT8_TD(r);
/* Wipe clean */
t = l = r = 0;
}
/* Key Schedule */
void cast_setkey(FAR cast_key *key, FAR uint8_t *rawkey, int keybytes)
{
uint32_t t[4];
uint32_t z[4];
uint32_t x[4];
int i;
/* Set number of rounds to 12 or 16, depending on key length */
key->rounds = (keybytes <= 10 ? 12 : 16);
/* Copy key to workspace x */
for (i = 0; i < 4; i++)
{
x[i] = 0;
if ((i * 4 + 0) < keybytes)
{
x[i] = (uint32_t)rawkey[i * 4 + 0] << 24;
}
if ((i * 4 + 1) < keybytes)
{
x[i] |= (uint32_t)rawkey[i * 4 + 1] << 16;
}
if ((i * 4 + 2) < keybytes)
{
x[i] |= (uint32_t)rawkey[i * 4 + 2] << 8;
}
if ((i * 4 + 3) < keybytes)
{
x[i] |= (uint32_t)rawkey[i * 4 + 3];
}
}
/* Generate 32 subkeys, four at a time */
for (i = 0; i < 32; i += 4)
{
switch (i & 4)
{
case 0:
t[0] = z[0] = x[0] ^ cast_sbox5[UINT8_TB(x[3])] ^
cast_sbox6[UINT8_TD(x[3])] ^
cast_sbox7[UINT8_TA(x[3])] ^
cast_sbox8[UINT8_TC(x[3])] ^
cast_sbox7[UINT8_TA(x[2])];
t[1] = z[1] = x[2] ^ cast_sbox5[UINT8_TA(z[0])] ^
cast_sbox6[UINT8_TC(z[0])] ^
cast_sbox7[UINT8_TB(z[0])] ^
cast_sbox8[UINT8_TD(z[0])] ^
cast_sbox8[UINT8_TC(x[2])];
t[2] = z[2] = x[3] ^ cast_sbox5[UINT8_TD(z[1])] ^
cast_sbox6[UINT8_TC(z[1])] ^
cast_sbox7[UINT8_TB(z[1])] ^
cast_sbox8[UINT8_TA(z[1])] ^
cast_sbox5[UINT8_TB(x[2])];
t[3] = z[3] = x[1] ^ cast_sbox5[UINT8_TC(z[2])] ^
cast_sbox6[UINT8_TB(z[2])] ^
cast_sbox7[UINT8_TD(z[2])] ^
cast_sbox8[UINT8_TA(z[2])] ^
cast_sbox6[UINT8_TD(x[2])];
break;
case 4:
t[0] = x[0] = z[2] ^ cast_sbox5[UINT8_TB(z[1])] ^
cast_sbox6[UINT8_TD(z[1])] ^
cast_sbox7[UINT8_TA(z[1])] ^
cast_sbox8[UINT8_TC(z[1])] ^
cast_sbox7[UINT8_TA(z[0])];
t[1] = x[1] = z[0] ^ cast_sbox5[UINT8_TA(x[0])] ^
cast_sbox6[UINT8_TC(x[0])] ^
cast_sbox7[UINT8_TB(x[0])] ^
cast_sbox8[UINT8_TD(x[0])] ^
cast_sbox8[UINT8_TC(z[0])];
t[2] = x[2] = z[1] ^ cast_sbox5[UINT8_TD(x[1])] ^
cast_sbox6[UINT8_TC(x[1])] ^
cast_sbox7[UINT8_TB(x[1])] ^
cast_sbox8[UINT8_TA(x[1])] ^
cast_sbox5[UINT8_TB(z[0])];
t[3] = x[3] = z[3] ^ cast_sbox5[UINT8_TC(x[2])] ^
cast_sbox6[UINT8_TB(x[2])] ^
cast_sbox7[UINT8_TD(x[2])] ^
cast_sbox8[UINT8_TA(x[2])] ^
cast_sbox6[UINT8_TD(z[0])];
break;
}
switch (i & 12)
{
case 0:
case 12:
key->xkey[i + 0] = cast_sbox5[UINT8_TA(t[2])] ^
cast_sbox6[UINT8_TB(t[2])] ^
cast_sbox7[UINT8_TD(t[1])] ^
cast_sbox8[UINT8_TC(t[1])];
key->xkey[i + 1] = cast_sbox5[UINT8_TC(t[2])] ^
cast_sbox6[UINT8_TD(t[2])] ^
cast_sbox7[UINT8_TB(t[1])] ^
cast_sbox8[UINT8_TA(t[1])];
key->xkey[i + 2] = cast_sbox5[UINT8_TA(t[3])] ^
cast_sbox6[UINT8_TB(t[3])] ^
cast_sbox7[UINT8_TD(t[0])] ^
cast_sbox8[UINT8_TC(t[0])];
key->xkey[i + 3] = cast_sbox5[UINT8_TC(t[3])] ^
cast_sbox6[UINT8_TD(t[3])] ^
cast_sbox7[UINT8_TB(t[0])] ^
cast_sbox8[UINT8_TA(t[0])];
break;
case 4:
case 8:
key->xkey[i + 0] = cast_sbox5[UINT8_TD(t[0])] ^
cast_sbox6[UINT8_TC(t[0])] ^
cast_sbox7[UINT8_TA(t[3])] ^
cast_sbox8[UINT8_TB(t[3])];
key->xkey[i + 1] = cast_sbox5[UINT8_TB(t[0])] ^
cast_sbox6[UINT8_TA(t[0])] ^
cast_sbox7[UINT8_TC(t[3])] ^
cast_sbox8[UINT8_TD(t[3])];
key->xkey[i + 2] = cast_sbox5[UINT8_TD(t[1])] ^
cast_sbox6[UINT8_TC(t[1])] ^
cast_sbox7[UINT8_TA(t[2])] ^
cast_sbox8[UINT8_TB(t[2])];
key->xkey[i + 3] = cast_sbox5[UINT8_TB(t[1])] ^
cast_sbox6[UINT8_TA(t[1])] ^
cast_sbox7[UINT8_TC(t[2])] ^
cast_sbox8[UINT8_TD(t[2])];
break;
}
switch (i & 12)
{
case 0:
key->xkey[i + 0] ^= cast_sbox5[UINT8_TC(z[0])];
key->xkey[i + 1] ^= cast_sbox6[UINT8_TC(z[1])];
key->xkey[i + 2] ^= cast_sbox7[UINT8_TB(z[2])];
key->xkey[i + 3] ^= cast_sbox8[UINT8_TA(z[3])];
break;
case 4:
key->xkey[i + 0] ^= cast_sbox5[UINT8_TA(x[2])];
key->xkey[i + 1] ^= cast_sbox6[UINT8_TB(x[3])];
key->xkey[i + 2] ^= cast_sbox7[UINT8_TD(x[0])];
key->xkey[i + 3] ^= cast_sbox8[UINT8_TD(x[1])];
break;
case 8:
key->xkey[i + 0] ^= cast_sbox5[UINT8_TB(z[2])];
key->xkey[i + 1] ^= cast_sbox6[UINT8_TA(z[3])];
key->xkey[i + 2] ^= cast_sbox7[UINT8_TC(z[0])];
key->xkey[i + 3] ^= cast_sbox8[UINT8_TC(z[1])];
break;
case 12:
key->xkey[i + 0] ^= cast_sbox5[UINT8_TD(x[0])];
key->xkey[i + 1] ^= cast_sbox6[UINT8_TD(x[1])];
key->xkey[i + 2] ^= cast_sbox7[UINT8_TA(x[2])];
key->xkey[i + 3] ^= cast_sbox8[UINT8_TB(x[3])];
break;
}
if (i >= 16)
{
key->xkey[i + 0] &= 31;
key->xkey[i + 1] &= 31;
key->xkey[i + 2] &= 31;
key->xkey[i + 3] &= 31;
}
}
/* Wipe clean */
explicit_bzero(t, sizeof(t));
explicit_bzero(x, sizeof(x));
explicit_bzero(z, sizeof(z));
}
/* Made in Canada */
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