/** Do 40-bit rc4-decrypt with key on bs of length len and
put the result in out
*/
static void
rc4Decrypt40b(const uint8_t *key, const uint8_t *bs,
const unsigned int len, uint8_t *out) {
uint8_t state[256];
register unsigned int i;
register uint8_t j, tmp;
/** initialize the state */
memcpy(state, initial_state, 256);
/** do the shuffle */
j = key[0];
state[0] = j;
state[j] = 0;
i = 0;
do {
key_pass(1);
key_pass(2);
key_pass(3);
key_pass(4);
key_pass(0);
} while(i < 255);
j = 0;
for(i=1;i<=len;++i) {
tmp = state[i];
j += tmp;
state[i] = state[j];
state[j] = tmp;
tmp += state[i];
out[i-1] = bs[i-1]^state[tmp];
}
}
static void
rc4DecryptArb(const uint8_t *key, const uint8_t *bs,
const unsigned int len, uint8_t *out) {
uint8_t state[256];
register unsigned int i;
register uint8_t j, tmp;
/** initialize the state */
memcpy(state, initial_state, 256);
/** do the shuffle */
j = 0;
i = -1;
do {
key_pass( (i % keyLen) );
} while(i < 255);
j = 0;
for(i=1;(unsigned int)i<=len;++i) {
tmp = state[i];
j += tmp;
state[i] = state[j];
state[j] = tmp;
tmp += state[i];
out[i-1] = bs[i-1]^state[tmp];
}
}
/** Do rc4-decrypt with key on bs of length 32 and compare it to match */
__attribute__ ((pure)) bool
rc4Match40b(const uint8_t *key, const uint8_t *bs,const uint8_t *match) {
uint8_t state[256];
register unsigned int i;
register uint8_t j, tmp;
/** initialize the state */
memcpy(state, initial_state, 256);
/** do the shuffle */
j = key[0];
state[0] = j;
state[j] = 0;
i = 0;
do {
key_pass(1);
key_pass(2);
key_pass(3);
key_pass(4);
key_pass(0);
} while(i < 255);
j = 0;
for(i=1;i<=32;++i) {
tmp = state[i];
j += tmp;
state[i] = state[j];
state[j] = tmp;
/**
Only continue if we match the match-strings characters.
The match should only happen once every 256 try or so and that is
the motivation behind the likely-hint
*/
tmp += state[i];
if(likely((bs[i-1]^state[tmp]) != match[i-1]))
return false;
}
return true;
}
/** Do 128-bit rc4-decrypt with key on bs of length len and
put the result in out
*/
static void
rc4Decrypt128b(const uint8_t *key, const uint8_t *bs,
const unsigned int len, uint8_t *out) {
uint8_t state[256];
register int i;
register uint8_t j, tmp;
assert(len < 256);
/** initialize the state */
memcpy(state, initial_state, 256);
/** do the shuffle */
j = 0;
i = -1;
do {
key_pass( 0);
key_pass( 1);
key_pass( 2);
key_pass( 3);
key_pass( 4);
key_pass( 5);
key_pass( 6);
key_pass( 7);
key_pass( 8);
key_pass( 9);
key_pass(10);
key_pass(11);
key_pass(12);
key_pass(13);
key_pass(14);
key_pass(15);
} while(i < 255);
j = 0;
for(i=1;(unsigned int)i<=len;++i) {
tmp = state[i];
j += tmp;
state[i] = state[j];
state[j] = tmp;
tmp += state[i];
out[i-1] = bs[i-1]^state[tmp];
}
}