pqc/common/randombytes.c
2019-01-15 15:35:25 +01:00

47 lines
1.1 KiB
C

#include <stdint.h>
#include "randombytes.h"
static uint32_t seed[32] = { 3,1,4,1,5,9,2,6,5,3,5,8,9,7,9,3,2,3,8,4,6,2,6,4,3,3,8,3,2,7,9,5 } ;
static uint32_t in[12];
static uint32_t out[8];
static int32_t outleft = 0;
#define ROTATE(x,b) (((x) << (b)) | ((x) >> (32 - (b))))
#define MUSH(i,b) x = t[i] += (((x ^ seed[i]) + sum) ^ ROTATE(x,b));
static void surf(void)
{
uint32_t t[12]; uint32_t x; uint32_t sum = 0;
int32_t r; int32_t i; int32_t loop;
for (i = 0;i < 12;++i) t[i] = in[i] ^ seed[12 + i];
for (i = 0;i < 8;++i) out[i] = seed[24 + i];
x = t[11];
for (loop = 0;loop < 2;++loop) {
for (r = 0;r < 16;++r) {
sum += 0x9e3779b9;
MUSH(0,5) MUSH(1,7) MUSH(2,9) MUSH(3,13)
MUSH(4,5) MUSH(5,7) MUSH(6,9) MUSH(7,13)
MUSH(8,5) MUSH(9,7) MUSH(10,9) MUSH(11,13)
}
for (i = 0;i < 8;++i) out[i] ^= t[i + 4];
}
}
void randombytes(uint8_t *x,uint64_t xlen)
{
uint64_t bak = xlen;
uint8_t *xbak = x;
while (xlen > 0) {
if (!outleft) {
if (!++in[0]) if (!++in[1]) if (!++in[2]) ++in[3];
surf();
outleft = 8;
}
*x = out[--outleft];
++x;
--xlen;
}
}