// This file is dual licensed under the terms of the Apache License, Version
// 2.0, and the BSD License. See the LICENSE file in the root of this
// repository for complete details.
uint8_t Cryptography_constant_time_bytes_eq(uint8_t *a, size_t len_a,
uint8_t *b, size_t len_b) {
size_t i = 0;
uint8_t mismatch = 0;
if (len_a != len_b) {
return 0;
}
for (i = 0; i < len_a; i++) {
mismatch |= a[i] ^ b[i];
}
/* Make sure any bits set are copied to the lowest bit */
mismatch |= mismatch >> 4;
mismatch |= mismatch >> 2;
mismatch |= mismatch >> 1;
/* Now check the low bit to see if it's set */
return (mismatch & 1) == 0;
}
td>