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Simplify internal code

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We know that Montgomery multiplication will never be called without an
RNG, so make that clear from the beginning of the function.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
This commit is contained in:
Manuel Pégourié-Gonnard 2021-06-15 11:29:26 +02:00
parent 7962bfaa79
commit 02b5705aa3
1 changed files with 5 additions and 5 deletions
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6
library/ecp.c
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@ -2384,6 +2384,9 @@ static int ecp_mul_mxz( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
mbedtls_mpi PX; mbedtls_mpi PX;
mbedtls_ecp_point_init( &RP ); mbedtls_mpi_init( &PX ); mbedtls_ecp_point_init( &RP ); mbedtls_mpi_init( &PX );
if( f_rng == NULL )
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
/* Save PX and read from P before writing to R, in case P == R */ /* Save PX and read from P before writing to R, in case P == R */
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &PX, &P->X ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &PX, &P->X ) );
MBEDTLS_MPI_CHK( mbedtls_ecp_copy( &RP, P ) ); MBEDTLS_MPI_CHK( mbedtls_ecp_copy( &RP, P ) );
@ -2397,7 +2400,6 @@ static int ecp_mul_mxz( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
MOD_ADD( RP.X ); MOD_ADD( RP.X );
/* Randomize coordinates of the starting point */ /* Randomize coordinates of the starting point */
if( f_rng != NULL )
MBEDTLS_MPI_CHK( ecp_randomize_mxz( grp, &RP, f_rng, p_rng ) ); MBEDTLS_MPI_CHK( ecp_randomize_mxz( grp, &RP, f_rng, p_rng ) );
/* Loop invariant: R = result so far, RP = R + P */ /* Loop invariant: R = result so far, RP = R + P */
@ -2430,9 +2432,7 @@ static int ecp_mul_mxz( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
* *
* Avoid the leak by randomizing coordinates before we normalize them. * Avoid the leak by randomizing coordinates before we normalize them.
*/ */
if( f_rng != NULL )
MBEDTLS_MPI_CHK( ecp_randomize_mxz( grp, R, f_rng, p_rng ) ); MBEDTLS_MPI_CHK( ecp_randomize_mxz( grp, R, f_rng, p_rng ) );
MBEDTLS_MPI_CHK( ecp_normalize_mxz( grp, R ) ); MBEDTLS_MPI_CHK( ecp_normalize_mxz( grp, R ) );
cleanup: cleanup: