Change mpi_safe_cond_assign() for more const-ness
diff --git a/library/bignum.c b/library/bignum.c
index 49321bb..9eceeba 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -206,8 +206,10 @@
/*
* Conditionally assign X = Y, without leaking information
+ * about whether the assignment was made or not.
+ * (Leaking information about the respective sizes of X and Y is ok however.)
*/
-int mpi_safe_cond_assign( mpi *X, mpi *Y, unsigned char assign )
+int mpi_safe_cond_assign( mpi *X, const mpi *Y, unsigned char assign )
{
int ret = 0;
size_t i;
@@ -215,16 +217,15 @@
if( assign * ( 1 - assign ) != 0 )
return( POLARSSL_ERR_MPI_BAD_INPUT_DATA );
- /* Make sure both MPIs have the same size */
- if( X->n > Y->n )
- MPI_CHK( mpi_grow( Y, X->n ) );
if( Y->n > X->n )
MPI_CHK( mpi_grow( X, Y->n ) );
/* Do the conditional assign safely */
X->s = X->s * (1 - assign) + Y->s * assign;
- for( i = 0; i < X->n; i++ )
+ for( i = 0; i < Y->n; i++ )
X->p[i] = X->p[i] * (1 - assign) + Y->p[i] * assign;
+ for( ; i < X->n; i++ )
+ X->p[i] *= (1 - assign);
cleanup:
return( ret );
diff --git a/library/ecp.c b/library/ecp.c
index 01b62f8..7b7d079 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -1392,7 +1392,7 @@
* Select precomputed point: R = sign(i) * T[ abs(i) / 2 ]
*/
static int ecp_select_comb( const ecp_group *grp, ecp_point *R,
- ecp_point T[], unsigned char t_len,
+ const ecp_point T[], unsigned char t_len,
unsigned char i )
{
int ret;
@@ -1425,7 +1425,7 @@
* Cost: d A + d D + 1 R
*/
static int ecp_mul_comb_core( const ecp_group *grp, ecp_point *R,
- ecp_point T[], unsigned char t_len,
+ const ecp_point T[], unsigned char t_len,
const unsigned char x[], size_t d,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )