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