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Save some small memory allocations inside ecp_mul()

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This commit is contained in:
Manuel Pégourié-Gonnard 2013-12-30 16:04:55 +01:00
parent fe40f484fb
commit 72c172a13d
1 changed files with 5 additions and 5 deletions
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10
library/ecp.c
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@ -915,6 +915,8 @@ cleanup:
* due to the choice of precomputed points in the modified comb method.
* So branches for these cases do not leak secret information.
*
* We accept Q->Z being unset (saving memory in tables) as meaning 1.
*
* Cost: 1A := 8M + 3S
*/
static int ecp_add_mixed( const ecp_group *grp, ecp_point *R,
@ -933,13 +935,13 @@ static int ecp_add_mixed( const ecp_group *grp, ecp_point *R,
if( mpi_cmp_int( &P->Z, 0 ) == 0 )
return( ecp_copy( R, Q ) );
if( mpi_cmp_int( &Q->Z, 0 ) == 0 )
if( Q->Z.p != NULL && mpi_cmp_int( &Q->Z, 0 ) == 0 )
return( ecp_copy( R, P ) );
/*
* Make sure Q coordinates are normalized
*/
if( mpi_cmp_int( &Q->Z, 1 ) != 0 )
if( Q->Z.p != NULL && mpi_cmp_int( &Q->Z, 1 ) != 0 )
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
mpi_init( &T1 ); mpi_init( &T2 ); mpi_init( &T3 ); mpi_init( &T4 );
@ -1240,9 +1242,6 @@ static int ecp_select_comb( const ecp_group *grp, ecp_point *R,
MPI_CHK( mpi_safe_cond_assign( &R->Y, &T[j].Y, j == ii ) );
}
/* The Z coordinate is always 1 */
MPI_CHK( mpi_lset( &R->Z, 1 ) );
/* Safely invert result if i is "negative" */
MPI_CHK( ecp_safe_invert_jac( grp, R, i >> 7 ) );
@ -1271,6 +1270,7 @@ static int ecp_mul_comb_core( const ecp_group *grp, ecp_point *R,
/* Start with a non-zero point and randomize its coordinates */
i = d;
MPI_CHK( ecp_select_comb( grp, R, T, t_len, x[i] ) );
MPI_CHK( mpi_lset( &R->Z, 1 ) );
if( f_rng != 0 )
MPI_CHK( ecp_randomize_jac( grp, R, f_rng, p_rng ) );