diff --git a/library/ecp.c b/library/ecp.c index 2168981afb..d3c6ccc8de 100644 --- a/library/ecp.c +++ b/library/ecp.c @@ -1738,18 +1738,17 @@ static int ecp_randomize_jac( const mbedtls_ecp_group *grp, mbedtls_ecp_point *p /* 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 ) + if( count++ > 30 ) { ret = MBEDTLS_ERR_ECP_RANDOM_FAILED; goto cleanup; } + + MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &l, p_size, f_rng, p_rng ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &l, ( p_size * 8 ) - grp->pbits ) ); } - while( mbedtls_mpi_cmp_int( &l, 1 ) <= 0 ); + while( ( mbedtls_mpi_cmp_int( &l, 1 ) <= 0 ) || + ( mbedtls_mpi_cmp_mpi( &l, &grp->P ) >= 0 ) ); /* Z = l * Z */ MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &pt->Z, &pt->Z, &l ) ); MOD_MUL( pt->Z ); @@ -2514,18 +2513,17 @@ static int ecp_randomize_mxz( const mbedtls_ecp_group *grp, mbedtls_ecp_point *P /* 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 ) + if( count++ > 30 ) { ret = MBEDTLS_ERR_ECP_RANDOM_FAILED; goto cleanup; } + + MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &l, p_size, f_rng, p_rng ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &l, ( p_size * 8 ) - grp->pbits ) ); } - while( mbedtls_mpi_cmp_int( &l, 1 ) <= 0 ); + while( ( mbedtls_mpi_cmp_int( &l, 1 ) <= 0 ) || + ( mbedtls_mpi_cmp_mpi( &l, &grp->P ) >= 0 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &P->X, &P->X, &l ) ); MOD_MUL( P->X ); MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &P->Z, &P->Z, &l ) ); MOD_MUL( P->Z );