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

Explain a little more

Browse source 
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine 2022-11-16 22:54:03 +01:00 committed by Janos Follath
parent 4380d7b7f3
commit 0b270a5603
1 changed files with 6 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

8
library/bignum_core.c
View file

@ -677,8 +677,10 @@ int mbedtls_mpi_core_exp_mod( mbedtls_mpi_uint *X,
* (limb_index=0, E_bit_index=0). */ * (limb_index=0, E_bit_index=0). */
size_t E_limb_index = E_limbs; size_t E_limb_index = E_limbs;
size_t E_bit_index = 0; size_t E_bit_index = 0;
mbedtls_mpi_uint window = 0; /* At any given time, window contains window_bits bits from E.
* window_bits can go up to wsize. */
size_t window_bits = 0; size_t window_bits = 0;
mbedtls_mpi_uint window = 0;
do do
{ {
@ -704,9 +706,11 @@ int mbedtls_mpi_core_exp_mod( mbedtls_mpi_uint *X,
if( window_bits == wsize || if( window_bits == wsize ||
( E_bit_index == 0 && E_limb_index == 0 ) ) ( E_bit_index == 0 && E_limb_index == 0 ) )
{ {
/* Select table entry, square and multiply */ /* Select Wtable[window] without leaking window through
* memory access patterns. */
mbedtls_mpi_core_ct_uint_table_lookup( Wselect, Wtable, mbedtls_mpi_core_ct_uint_table_lookup( Wselect, Wtable,
AN_limbs, welem, window ); AN_limbs, welem, window );
/* Multiply X by the selected element. */
mbedtls_mpi_core_montmul( X, X, Wselect, AN_limbs, N, AN_limbs, mm, temp ); mbedtls_mpi_core_montmul( X, X, Wselect, AN_limbs, N, AN_limbs, mm, temp );
window = 0; window = 0;
window_bits = 0; window_bits = 0;