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

ECP: use mbedtls_mpi_random for blinding

Browse source 
Instead of generating blinding values in a not-quite-uniform way
(https://github.com/ARMmbed/mbedtls/issues/4245) with copy-pasted
code, use mbedtls_mpi_random().

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine 2021-03-29 22:28:50 +02:00
parent 60d8b98d48
commit 5921517126
1 changed files with 6 additions and 32 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

38
library/ecp.c
View file

@ -1713,26 +1713,11 @@ static int ecp_randomize_jac( const mbedtls_ecp_group *grp, mbedtls_ecp_point *p
#else
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_mpi l, ll;
int count = 0;
size_t p_size = ( grp->pbits + 7 ) / 8;
mbedtls_mpi_init( &l ); mbedtls_mpi_init( &ll );
/* Generate l such that 1 < l < p */
do
{
MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &l, p_size, f_rng, p_rng ) );
while( mbedtls_mpi_cmp_mpi( &l, &grp->P ) >= 0 )
MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &l, 1 ) );
if( count++ > 10 )
{
ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
goto cleanup;
}
}
while( mbedtls_mpi_cmp_int( &l, 1 ) <= 0 );
MBEDTLS_MPI_CHK( mbedtls_mpi_random( &l, 2, &grp->P, f_rng, p_rng ) );
/* Z = l * Z */
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mod( grp, &pt->Z, &pt->Z, &l ) );
@ -1748,6 +1733,8 @@ static int ecp_randomize_jac( const mbedtls_ecp_group *grp, mbedtls_ecp_point *p
cleanup:
mbedtls_mpi_free( &l ); mbedtls_mpi_free( &ll );
if( ret == MBEDTLS_ERR_MPI_NOT_ACCEPTABLE )
ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
return( ret );
#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_RANDOMIZE_JAC_ALT) */
}
@ -2502,25 +2489,10 @@ static int ecp_randomize_mxz( const mbedtls_ecp_group *grp, mbedtls_ecp_point *P
#else
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_mpi l;
int count = 0;
size_t p_size = ( grp->pbits + 7 ) / 8;
mbedtls_mpi_init( &l );
/* Generate l such that 1 < l < p */
do
{
MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &l, p_size, f_rng, p_rng ) );
while( mbedtls_mpi_cmp_mpi( &l, &grp->P ) >= 0 )
MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &l, 1 ) );
if( count++ > 10 )
{
ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
goto cleanup;
}
}
while( mbedtls_mpi_cmp_int( &l, 1 ) <= 0 );
MBEDTLS_MPI_CHK( mbedtls_mpi_random( &l, 2, &grp->P, f_rng, p_rng ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mod( grp, &P->X, &P->X, &l ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mod( grp, &P->Z, &P->Z, &l ) );
@ -2528,6 +2500,8 @@ static int ecp_randomize_mxz( const mbedtls_ecp_group *grp, mbedtls_ecp_point *P
cleanup:
mbedtls_mpi_free( &l );
if( ret == MBEDTLS_ERR_MPI_NOT_ACCEPTABLE )
ret = MBEDTLS_ERR_ECP_RANDOM_FAILED;
return( ret );
#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_RANDOMIZE_MXZ_ALT) */
}