blob: 149e52d7b03f22ccf4ec6eaa6e40c723a6d540b7 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
|
#include "verify.h"
#include <stddef.h>
#include <stdint.h>
/*************************************************
* Name: verify
*
* Description: Compare two arrays for equality in constant time.
*
* Arguments: const uint8_t *a: pointer to first byte array
* const uint8_t *b: pointer to second byte array
* size_t len: length of the byte arrays
*
* Returns 0 if the byte arrays are equal, 1 otherwise
**************************************************/
uint8_t PQCLEAN_KYBER512_CLEAN_verify(const uint8_t *a, const uint8_t *b, size_t len) {
uint64_t r;
size_t i;
r = 0;
for (i = 0; i < len; i++) {
r |= a[i] ^ b[i];
}
r = (-r) >> 63;
return (uint8_t)r;
}
/*************************************************
* Name: cmov
*
* Description: Copy len bytes from x to r if b is 1;
* don't modify x if b is 0. Requires b to be in {0,1};
* assumes two's complement representation of negative integers.
* Runs in constant time.
*
* Arguments: uint8_t *r: pointer to output byte array
* const uint8_t *x: pointer to input byte array
* size_t len: Amount of bytes to be copied
* uint8_t b: Condition bit; has to be in {0,1}
**************************************************/
void PQCLEAN_KYBER512_CLEAN_cmov(uint8_t *r, const uint8_t *x, size_t len, uint8_t b) {
size_t i;
b = -b;
for (i = 0; i < len; i++) {
r[i] ^= b & (x[i] ^ r[i]);
}
}
|
