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

Remove argument checking from constant time functions

Browse source 
Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
This commit is contained in:
Gabor Mezei 2022-09-15 19:12:06 +02:00
parent b27b1c5db0
commit 9f6615f146
No known key found for this signature in database
GPG key ID: F072ACA227ACD71D
2 changed files with 31 additions and 64 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

65
library/bignum_core.c
View file

@ -162,59 +162,36 @@ void mbedtls_mpi_core_bigendian_to_host( mbedtls_mpi_uint *A,
}
}
int mbedtls_mpi_core_cond_assign( mbedtls_mpi_uint *X,
size_t X_limbs,
const mbedtls_mpi_uint *Y,
size_t Y_limbs,
unsigned char assign )
void mbedtls_mpi_core_cond_assign( mbedtls_mpi_uint *X,
size_t X_limbs,
const mbedtls_mpi_uint *Y,
size_t Y_limbs,
unsigned char assign )
{
if( X_limbs < Y_limbs )
return( MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL );
/* all-bits 1 if assign is 1, all-bits 0 if assign is 0 */
mbedtls_mpi_uint limb_mask = mbedtls_ct_mpi_uint_mask( assign );
if( X != NULL && Y != NULL )
{
/* all-bits 1 if assign is 1, all-bits 0 if assign is 0 */
mbedtls_mpi_uint limb_mask = mbedtls_ct_mpi_uint_mask( assign );
mbedtls_ct_mpi_uint_cond_assign( Y_limbs, X, Y, assign );
mbedtls_ct_mpi_uint_cond_assign( X_limbs, X, Y, assign );
for( size_t i = Y_limbs; i < X_limbs; i++ )
X[i] &= ~limb_mask;
return( 0 );
}
return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
for( size_t i = Y_limbs; i < X_limbs; i++ )
X[i] &= ~limb_mask;
}
int mbedtls_mpi_core_cond_swap( mbedtls_mpi_uint *X,
size_t X_limbs,
mbedtls_mpi_uint *Y,
size_t Y_limbs,
unsigned char swap )
void mbedtls_mpi_core_cond_swap( mbedtls_mpi_uint *X,
size_t X_limbs,
mbedtls_mpi_uint *Y,
size_t Y_limbs,
unsigned char swap )
{
if( X == Y )
return( 0 );
/* all-bits 1 if swap is 1, all-bits 0 if swap is 0 */
mbedtls_mpi_uint limb_mask = mbedtls_ct_mpi_uint_mask( swap );
if( X_limbs != Y_limbs )
return( MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL );
if( X != NULL && Y != NULL )
for( size_t i = 0; i < X_limbs; i++ )
{
/* all-bits 1 if swap is 1, all-bits 0 if swap is 0 */
mbedtls_mpi_uint limb_mask = mbedtls_ct_mpi_uint_mask( swap );
for( size_t i = 0; i < X_limbs; i++ )
{
mbedtls_mpi_uint tmp = X[i];
X[i] = ( X[i] & ~limb_mask ) | ( Y[i] & limb_mask );
Y[i] = ( Y[i] & ~limb_mask ) | ( tmp & limb_mask );
}
return( 0 );
mbedtls_mpi_uint tmp = X[i];
X[i] = ( X[i] & ~limb_mask ) | ( Y[i] & limb_mask );
Y[i] = ( Y[i] & ~limb_mask ) | ( tmp & limb_mask );
}
return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
}
int mbedtls_mpi_core_read_le( mbedtls_mpi_uint *X,

30
library/bignum_core.h
View file

@ -93,17 +93,12 @@ void mbedtls_mpi_core_bigendian_to_host( mbedtls_mpi_uint *A,
* \warning If \p assign is neither 0 nor 1, the result of this function
* is indeterminate, and the resulting value in \p X might be
* neither its original value nor the value in \p Y.
*
* \return \c 0 if successful.
* \return #MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL if \p X isn't
* large enough to hold the value in \p Y.
* \return #MBEDTLS_ERR_MPI_BAD_INPUT_DATA if \p X or \p Y is invalid.
*/
int mbedtls_mpi_core_cond_assign( mbedtls_mpi_uint *X,
size_t X_limbs,
const mbedtls_mpi_uint *Y,
size_t Y_limbs,
unsigned char assign );
void mbedtls_mpi_core_cond_assign( mbedtls_mpi_uint *X,
size_t X_limbs,
const mbedtls_mpi_uint *Y,
size_t Y_limbs,
unsigned char assign );
/**
* \brief Perform a safe conditional copy of MPI which doesn't reveal whether
@ -126,17 +121,12 @@ int mbedtls_mpi_core_cond_assign( mbedtls_mpi_uint *X,
* \warning If \p swap is neither 0 nor 1, the result of this function
* is indeterminate, and both \p X and \p Y might end up with
* values different to either of the original ones.
*
* \return \c 0 if successful.
* \return #MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL if the size of
* \p X and \p Y is differ.
* \return #MBEDTLS_ERR_MPI_BAD_INPUT_DATA if \p X or \p Y is invalid.
*/
int mbedtls_mpi_core_cond_swap( mbedtls_mpi_uint *X,
size_t X_limbs,
mbedtls_mpi_uint *Y,
size_t Y_limbs,
unsigned char swap );
void mbedtls_mpi_core_cond_swap( mbedtls_mpi_uint *X,
size_t X_limbs,
mbedtls_mpi_uint *Y,
size_t Y_limbs,
unsigned char swap );
/** Import X from unsigned binary data, little-endian.
*