diff --git a/library/ecp.c b/library/ecp.c index cdffa1ca9..d63c571cd 100644 --- a/library/ecp.c +++ b/library/ecp.c @@ -2395,35 +2395,39 @@ static int ecp_double_add_mxz( const mbedtls_ecp_group *grp, return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE ); #else int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; - mbedtls_mpi A, AA, B, BB, E, C, D, DA, CB; - mbedtls_mpi_init( &A ); mbedtls_mpi_init( &AA ); mbedtls_mpi_init( &B ); - mbedtls_mpi_init( &BB ); mbedtls_mpi_init( &E ); mbedtls_mpi_init( &C ); - mbedtls_mpi_init( &D ); mbedtls_mpi_init( &DA ); mbedtls_mpi_init( &CB ); + mbedtls_mpi T0,T1,T2,T3; - MPI_ECP_ADD( &A, &P->X, &P->Z ); - MPI_ECP_SUB( &B, &P->X, &P->Z ); - MPI_ECP_ADD( &C, &Q->X, &Q->Z ); - MPI_ECP_SUB( &D, &Q->X, &Q->Z ); - MPI_ECP_MUL( &DA, &D, &A ); /* D no longer needed */ - MPI_ECP_MUL( &CB, &C, &B ); /* C no longer needed */ - MPI_ECP_SQR( &AA, &A ); /* A no longer needed */ - MPI_ECP_SQR( &BB, &B ); /* B no longer needed */ - MPI_ECP_MUL( &R->X, &AA, &BB ); - MPI_ECP_SUB( &E, &AA, &BB ); /* AA no longer needed */ - MPI_ECP_MUL( &R->Z, &grp->A, &E ); - MPI_ECP_ADD( &R->Z, &BB, &R->Z ); /* BB no longer needed */ - MPI_ECP_ADD( &S->X, &DA, &CB ); + mbedtls_mpi_init( &T0 ); + mbedtls_mpi_init( &T1 ); + mbedtls_mpi_init( &T2 ); + mbedtls_mpi_init( &T3 ); + + MPI_ECP_ADD( &T0, &P->X, &P->Z ); + MPI_ECP_SUB( &T1, &P->X, &P->Z ); + MPI_ECP_ADD( &T2, &Q->X, &Q->Z ); + MPI_ECP_SUB( &T3, &Q->X, &Q->Z ); + MPI_ECP_MUL( &T3, &T3, &T0 ); + MPI_ECP_MUL( &T2, &T2, &T1 ); + MPI_ECP_SQR( &T0, &T0 ); + MPI_ECP_SQR( &T1, &T1 ); + MPI_ECP_MUL( &R->X, &T0, &T1 ); + MPI_ECP_SUB( &T0, &T0, &T1 ); + MPI_ECP_MUL( &R->Z, &grp->A, &T0 ); + MPI_ECP_ADD( &R->Z, &T1, &R->Z ); + MPI_ECP_ADD( &S->X, &T3, &T2 ); MPI_ECP_SQR( &S->X, &S->X ); - MPI_ECP_SUB( &S->Z, &DA, &CB ); + MPI_ECP_SUB( &S->Z, &T3, &T2 ); MPI_ECP_SQR( &S->Z, &S->Z ); MPI_ECP_MUL( &S->Z, d, &S->Z ); - MPI_ECP_MUL( &R->Z, &E, &R->Z ); + MPI_ECP_MUL( &R->Z, &T0, &R->Z ); cleanup: - mbedtls_mpi_free( &A ); mbedtls_mpi_free( &AA ); mbedtls_mpi_free( &B ); - mbedtls_mpi_free( &BB ); mbedtls_mpi_free( &E ); mbedtls_mpi_free( &C ); - mbedtls_mpi_free( &D ); mbedtls_mpi_free( &DA ); mbedtls_mpi_free( &CB ); + + mbedtls_mpi_free( &T0 ); + mbedtls_mpi_free( &T1 ); + mbedtls_mpi_free( &T2 ); + mbedtls_mpi_free( &T3 ); return( ret ); #endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_DOUBLE_ADD_MXZ_ALT) */