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Faster validate_prng_nonce

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This commit is contained in:
Philippe Teuwen 2024-07-29 11:54:53 +02:00
commit bd3e8db852
1 changed files with 7 additions and 4 deletions
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11
common/crapto1/crapto1.c
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@ -430,10 +430,13 @@ int nonce_distance(uint32_t from, uint32_t to) {
* false = hardend prng
*/
bool validate_prng_nonce(uint32_t nonce) {
// init prng table:
if (nonce_distance(nonce, nonce) == -1)
return false;
return ((65535 - dist[nonce >> 16] + dist[nonce & 0xffff]) % 65535) == 16;
uint16_t x = nonce >> 16;
x = (x & 0xff) << 8 | x >> 8;
for (uint8_t i = 0; i<16; i++) {
x = x >> 1 | (x ^ x >> 2 ^ x >> 3 ^ x >> 5) << 15;
}
x = (x & 0xff) << 8 | x >> 8;
return x == (nonce & 0xFFFF);
}
static uint32_t fastfwd[2][8] = {