Full restart support in ecp_mul_comb_core()
Still recomputing table every time, though.
@@ -108,6 +108,7 @@ struct mbedtls_ecp_restart {
mbedtls_mpi m; /* saved argument: scalar */
mbedtls_ecp_point P; /* saved argument: point */
mbedtls_ecp_point R; /* current intermediate result */
+ size_t i; /* current index in various loops, 0 outside */
enum {
ecp_rs_init = 0,
ecp_rs_final_norm,
@@ -1409,15 +1410,26 @@ static int ecp_mul_comb_core( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R
mbedtls_ecp_point_init( &Txi );
+#if defined(MBEDTLS_ECP_EARLY_RETURN)
+ if( grp->rs != NULL && grp->rs->i != 0 )
+ {
+ /* restore current index (R already pointing to grp->rs->R) */
+ i = grp->rs->i;
+ }
+ else
+#endif
+ {
/* Start with a non-zero point and randomize its coordinates */
i = d;
MBEDTLS_MPI_CHK( ecp_select_comb( grp, R, T, t_len, x[i] ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &R->Z, 1 ) );
if( f_rng != 0 )
MBEDTLS_MPI_CHK( ecp_randomize_jac( grp, R, f_rng, p_rng ) );
+ }
while( i-- != 0 )
{
+ ECP_BUDGET( ECP_OPS_DBL + ECP_OPS_ADD );
MBEDTLS_MPI_CHK( ecp_double_jac( grp, R, R ) );
MBEDTLS_MPI_CHK( ecp_select_comb( grp, &Txi, T, t_len, x[i] ) );
MBEDTLS_MPI_CHK( ecp_add_mixed( grp, R, R, &Txi ) );
@@ -1427,6 +1439,23 @@ cleanup:
mbedtls_ecp_point_free( &Txi );
+#if defined(MBEDTLS_ECP_EARLY_RETURN)
+ if( grp->rs != NULL )
+ {
+ if( ret == 0 )
+ {
+ grp->rs->state++;
+ grp->rs->i = 0;
+ }
+ else if( ret == MBEDTLS_ERR_ECP_IN_PROGRESS )
+ {
+ /* was decreased before actually doing it */
+ grp->rs->i = i + 1;
+ /* no need to save R, already pointing to grp->rs->R */
+ }
+ }
+#endif
+
return( ret );
}
@@ -1513,9 +1542,6 @@ static int ecp_mul_comb_after_precomp( const mbedtls_ecp_group *grp,
if( grp->rs != NULL )
grp->rs->state++;
#endif
-
- /* XXX: temporary: should have counted some ops */
- ECP_BUDGET( 42 );
}
ECP_BUDGET( ECP_OPS_INV );
