49 lines
1.5 KiB
C
49 lines
1.5 KiB
C
#include "SABER_params.h"
|
||
#include "api.h"
|
||
#include "cbd.h"
|
||
#include <stdint.h>
|
||
/*---------------------------------------------------------------------
|
||
This file has been adapted from the implementation
|
||
(available at, Public Domain https://github.com/pq-crystals/kyber)
|
||
of "CRYSTALS – Kyber: a CCA-secure module-lattice-based KEM"
|
||
by : Joppe Bos, Leo Ducas, Eike Kiltz, Tancrede Lepoint,
|
||
Vadim Lyubashevsky, John M. Schanck, Peter Schwabe & Damien stehle
|
||
----------------------------------------------------------------------*/
|
||
|
||
|
||
static uint64_t load_littleendian(const uint8_t *x, int bytes) {
|
||
int i;
|
||
uint64_t r = x[0];
|
||
for (i = 1; i < bytes; i++) {
|
||
r |= (uint64_t)x[i] << (8 * i);
|
||
}
|
||
return r;
|
||
}
|
||
|
||
void PQCLEAN_FIRESABER_CLEAN_cbd(uint16_t s[SABER_N], const uint8_t buf[SABER_POLYCOINBYTES]) {
|
||
uint32_t t, d, a[4], b[4];
|
||
int i, j;
|
||
|
||
for (i = 0; i < SABER_N / 4; i++) {
|
||
t = (uint32_t) load_littleendian(buf + 3 * i, 3);
|
||
d = 0;
|
||
for (j = 0; j < 3; j++) {
|
||
d += (t >> j) & 0x249249;
|
||
}
|
||
|
||
a[0] = d & 0x7;
|
||
b[0] = (d >> 3) & 0x7;
|
||
a[1] = (d >> 6) & 0x7;
|
||
b[1] = (d >> 9) & 0x7;
|
||
a[2] = (d >> 12) & 0x7;
|
||
b[2] = (d >> 15) & 0x7;
|
||
a[3] = (d >> 18) & 0x7;
|
||
b[3] = (d >> 21);
|
||
|
||
s[4 * i + 0] = (uint16_t)(a[0] - b[0]);
|
||
s[4 * i + 1] = (uint16_t)(a[1] - b[1]);
|
||
s[4 * i + 2] = (uint16_t)(a[2] - b[2]);
|
||
s[4 * i + 3] = (uint16_t)(a[3] - b[3]);
|
||
}
|
||
}
|