yuzu-emu/mbedtls
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

Add impl of mbedtls_ct_memcpy_if

Browse source 
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
This commit is contained in:
Dave Rodgman 2023-05-17 12:34:56 +01:00
parent 293eedd3ad
commit 7fe6e6fb2b
1 changed files with 29 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

29
library/constant_time.c
View file

@ -346,6 +346,35 @@ void mbedtls_ct_memmove_left(void *start, size_t total, size_t offset)
#endif /* MBEDTLS_PKCS1_V15 && MBEDTLS_RSA_C && ! MBEDTLS_RSA_ALT */
void mbedtls_ct_memcpy_if(mbedtls_ct_condition_t condition,
unsigned char *dest,
const unsigned char *src1,
const unsigned char *src2,
size_t len)
{
const uint32_t mask = (uint32_t) condition;
const uint32_t not_mask = (uint32_t) ~mbedtls_ct_compiler_opaque(condition);
/* If src2 is NULL and condition == 0, then this function has no effect.
* In this case, copy from dest back into dest. */
if (src2 == NULL) {
src2 = dest;
}
/* dest[i] = c1 == c2 ? src[i] : dest[i] */
size_t i = 0;
#if defined(MBEDTLS_EFFICIENT_UNALIGNED_ACCESS)
for (; (i + 4) <= len; i += 4) {
uint32_t a = mbedtls_get_unaligned_uint32(src1 + i) & mask;
uint32_t b = mbedtls_get_unaligned_uint32(src2 + i) & not_mask;
mbedtls_put_unaligned_uint32(dest + i, a | b);
}
#endif /* MBEDTLS_EFFICIENT_UNALIGNED_ACCESS */
for (; i < len; i++) {
dest[i] = (src1[i] & mask) | (src2[i] & not_mask);
}
}
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
void mbedtls_ct_memcpy_if_eq(unsigned char *dest,