void cast128_decrypt(const cast128_key* key, const u_int8_t* inblock,
u_int8_t* outblock)
{
u_int32_t t, l, r;
/* Get inblock into l,r */
r = ((u_int32_t)inblock[0] << 24) | ((u_int32_t)inblock[1] << 16) |
((u_int32_t)inblock[2] << 8) | (u_int32_t)inblock[3];
l = ((u_int32_t)inblock[4] << 24) | ((u_int32_t)inblock[5] << 16) |
((u_int32_t)inblock[6] << 8) | (u_int32_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] = U_INT8_Ta(l);
outblock[1] = U_INT8_Tb(l);
outblock[2] = U_INT8_Tc(l);
outblock[3] = U_INT8_Td(l);
outblock[4] = U_INT8_Ta(r);
outblock[5] = U_INT8_Tb(r);
outblock[6] = U_INT8_Tc(r);
outblock[7] = U_INT8_Td(r);
/* Wipe clean */
t = l = r = 0;
}
void cast_setkey(cast_key* key, u_int8_t* rawkey, int keybytes)
{
u_int32_t t[4], z[4], 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] = (u_int32_t)rawkey[i*4+0] << 24;
if ((i*4+1) < keybytes) x[i] |= (u_int32_t)rawkey[i*4+1] << 16;
if ((i*4+2) < keybytes) x[i] |= (u_int32_t)rawkey[i*4+2] << 8;
if ((i*4+3) < keybytes) x[i] |= (u_int32_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[U_INT8_Tb(x[3])] ^
cast_sbox6[U_INT8_Td(x[3])] ^ cast_sbox7[U_INT8_Ta(x[3])] ^
cast_sbox8[U_INT8_Tc(x[3])] ^ cast_sbox7[U_INT8_Ta(x[2])];
t[1] = z[1] = x[2] ^ cast_sbox5[U_INT8_Ta(z[0])] ^
cast_sbox6[U_INT8_Tc(z[0])] ^ cast_sbox7[U_INT8_Tb(z[0])] ^
cast_sbox8[U_INT8_Td(z[0])] ^ cast_sbox8[U_INT8_Tc(x[2])];
t[2] = z[2] = x[3] ^ cast_sbox5[U_INT8_Td(z[1])] ^
cast_sbox6[U_INT8_Tc(z[1])] ^ cast_sbox7[U_INT8_Tb(z[1])] ^
cast_sbox8[U_INT8_Ta(z[1])] ^ cast_sbox5[U_INT8_Tb(x[2])];
t[3] = z[3] = x[1] ^ cast_sbox5[U_INT8_Tc(z[2])] ^
cast_sbox6[U_INT8_Tb(z[2])] ^ cast_sbox7[U_INT8_Td(z[2])] ^
cast_sbox8[U_INT8_Ta(z[2])] ^ cast_sbox6[U_INT8_Td(x[2])];
break;
case 4:
t[0] = x[0] = z[2] ^ cast_sbox5[U_INT8_Tb(z[1])] ^
cast_sbox6[U_INT8_Td(z[1])] ^ cast_sbox7[U_INT8_Ta(z[1])] ^
cast_sbox8[U_INT8_Tc(z[1])] ^ cast_sbox7[U_INT8_Ta(z[0])];
t[1] = x[1] = z[0] ^ cast_sbox5[U_INT8_Ta(x[0])] ^
cast_sbox6[U_INT8_Tc(x[0])] ^ cast_sbox7[U_INT8_Tb(x[0])] ^
cast_sbox8[U_INT8_Td(x[0])] ^ cast_sbox8[U_INT8_Tc(z[0])];
t[2] = x[2] = z[1] ^ cast_sbox5[U_INT8_Td(x[1])] ^
cast_sbox6[U_INT8_Tc(x[1])] ^ cast_sbox7[U_INT8_Tb(x[1])] ^
cast_sbox8[U_INT8_Ta(x[1])] ^ cast_sbox5[U_INT8_Tb(z[0])];
t[3] = x[3] = z[3] ^ cast_sbox5[U_INT8_Tc(x[2])] ^
cast_sbox6[U_INT8_Tb(x[2])] ^ cast_sbox7[U_INT8_Td(x[2])] ^
cast_sbox8[U_INT8_Ta(x[2])] ^ cast_sbox6[U_INT8_Td(z[0])];
break;
}
switch (i & 12) {
case 0:
case 12:
key->xkey[i+0] = cast_sbox5[U_INT8_Ta(t[2])] ^ cast_sbox6[U_INT8_Tb(t[2])] ^
cast_sbox7[U_INT8_Td(t[1])] ^ cast_sbox8[U_INT8_Tc(t[1])];
key->xkey[i+1] = cast_sbox5[U_INT8_Tc(t[2])] ^ cast_sbox6[U_INT8_Td(t[2])] ^
cast_sbox7[U_INT8_Tb(t[1])] ^ cast_sbox8[U_INT8_Ta(t[1])];
key->xkey[i+2] = cast_sbox5[U_INT8_Ta(t[3])] ^ cast_sbox6[U_INT8_Tb(t[3])] ^
cast_sbox7[U_INT8_Td(t[0])] ^ cast_sbox8[U_INT8_Tc(t[0])];
key->xkey[i+3] = cast_sbox5[U_INT8_Tc(t[3])] ^ cast_sbox6[U_INT8_Td(t[3])] ^
cast_sbox7[U_INT8_Tb(t[0])] ^ cast_sbox8[U_INT8_Ta(t[0])];
break;
case 4:
case 8:
key->xkey[i+0] = cast_sbox5[U_INT8_Td(t[0])] ^ cast_sbox6[U_INT8_Tc(t[0])] ^
cast_sbox7[U_INT8_Ta(t[3])] ^ cast_sbox8[U_INT8_Tb(t[3])];
key->xkey[i+1] = cast_sbox5[U_INT8_Tb(t[0])] ^ cast_sbox6[U_INT8_Ta(t[0])] ^
cast_sbox7[U_INT8_Tc(t[3])] ^ cast_sbox8[U_INT8_Td(t[3])];
key->xkey[i+2] = cast_sbox5[U_INT8_Td(t[1])] ^ cast_sbox6[U_INT8_Tc(t[1])] ^
cast_sbox7[U_INT8_Ta(t[2])] ^ cast_sbox8[U_INT8_Tb(t[2])];
key->xkey[i+3] = cast_sbox5[U_INT8_Tb(t[1])] ^ cast_sbox6[U_INT8_Ta(t[1])] ^
cast_sbox7[U_INT8_Tc(t[2])] ^ cast_sbox8[U_INT8_Td(t[2])];
break;
}
switch (i & 12) {
case 0:
key->xkey[i+0] ^= cast_sbox5[U_INT8_Tc(z[0])];
key->xkey[i+1] ^= cast_sbox6[U_INT8_Tc(z[1])];
key->xkey[i+2] ^= cast_sbox7[U_INT8_Tb(z[2])];
key->xkey[i+3] ^= cast_sbox8[U_INT8_Ta(z[3])];
break;
case 4:
key->xkey[i+0] ^= cast_sbox5[U_INT8_Ta(x[2])];
key->xkey[i+1] ^= cast_sbox6[U_INT8_Tb(x[3])];
key->xkey[i+2] ^= cast_sbox7[U_INT8_Td(x[0])];
key->xkey[i+3] ^= cast_sbox8[U_INT8_Td(x[1])];
break;
case 8:
key->xkey[i+0] ^= cast_sbox5[U_INT8_Tb(z[2])];
key->xkey[i+1] ^= cast_sbox6[U_INT8_Ta(z[3])];
key->xkey[i+2] ^= cast_sbox7[U_INT8_Tc(z[0])];
key->xkey[i+3] ^= cast_sbox8[U_INT8_Tc(z[1])];
break;
case 12:
key->xkey[i+0] ^= cast_sbox5[U_INT8_Td(x[0])];
key->xkey[i+1] ^= cast_sbox6[U_INT8_Td(x[1])];
key->xkey[i+2] ^= cast_sbox7[U_INT8_Ta(x[2])];
key->xkey[i+3] ^= cast_sbox8[U_INT8_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 */
for (i = 0; i < 4; i++) {
t[i] = x[i] = z[i] = 0;
}
}