Clarifications in comments; code cosmetics & style
diff --git a/library/ecp.c b/library/ecp.c
index 2fe456f..574b181 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -109,11 +109,11 @@
*/
int ecp_copy( ecp_point *P, const ecp_point *Q )
{
- int ret = 0;
+ int ret;
if( Q->is_zero ) {
ecp_set_zero( P );
- return( ret );
+ return( 0 );
}
P->is_zero = Q->is_zero;
@@ -130,7 +130,7 @@
int ecp_point_read_string( ecp_point *P, int radix,
const char *x, const char *y )
{
- int ret = 0;
+ int ret;
P->is_zero = 0;
MPI_CHK( mpi_read_string( &P->X, radix, x ) );
@@ -147,7 +147,7 @@
const char *p, const char *b,
const char *gx, const char *gy, const char *n)
{
- int ret = 0;
+ int ret;
MPI_CHK( mpi_read_string( &grp->P, radix, p ) );
MPI_CHK( mpi_read_string( &grp->B, radix, b ) );
@@ -159,15 +159,11 @@
}
/*
- * Wrapper around fast quasi-modp functions, with fallback to mpi_mod_mpi
- *
- * The quasi-modp functions expect an mpi N such that 0 <= N < 2^(2*pbits)
- * and change it in-place so that it can easily be brought in the 0..P-1
- * range by a few additions or substractions.
+ * Wrapper around fast quasi-modp functions, with fall-back to mpi_mod_mpi
*/
static int ecp_modp( mpi *N, const ecp_group *grp )
{
- int ret = 0;
+ int ret;
if( grp->modp == NULL )
return( mpi_mod_mpi( N, N, &grp->P ) );
@@ -206,7 +202,7 @@
*/
static int ecp_mod_p521( mpi *N )
{
- int ret = 0;
+ int ret;
t_uint Mp[P521_SIZE_INT];
mpi M;
@@ -353,13 +349,13 @@
}
/*
- * Fast mod-p functions expect an argument in the 0 .. p^2 range.
+ * Fast mod-p functions expect their argument to be in the 0..p^2 range.
*
- * In order to garantee that, we need to ensure that operands of
- * mpi_mul_mpi are in the 0 .. p range. So, after each operation we will
+ * In order to guarantee that, we need to ensure that operands of
+ * mpi_mul_mpi are in the 0..p range. So, after each operation we will
* bring the result back to this range.
*
- * The following macros are helpers for that.
+ * The following macros are shortcuts for doing that.
*/
/*
@@ -412,7 +408,7 @@
*/
static int ecp_ptjac_copy( ecp_ptjac *R, const ecp_ptjac *P )
{
- int ret = 0;
+ int ret;
MPI_CHK( mpi_copy( &R->X, &P->X ) );
MPI_CHK( mpi_copy( &R->Y, &P->Y ) );
@@ -427,7 +423,7 @@
*/
static int ecp_ptjac_set_zero( ecp_ptjac *P )
{
- int ret = 0;
+ int ret;
MPI_CHK( mpi_lset( &P->X, 1 ) );
MPI_CHK( mpi_lset( &P->Y, 1 ) );
@@ -442,7 +438,7 @@
*/
static int ecp_aff_to_jac( ecp_ptjac *jac, const ecp_point *aff )
{
- int ret = 0;
+ int ret;
if( aff->is_zero )
return( ecp_ptjac_set_zero( jac ) );
@@ -461,7 +457,7 @@
static int ecp_jac_to_aff( const ecp_group *grp,
ecp_point *aff, const ecp_ptjac *jac )
{
- int ret = 0;
+ int ret;
mpi Zi, ZZi, T;
if( mpi_cmp_int( &jac->Z, 0 ) == 0 ) {
@@ -499,7 +495,7 @@
static int ecp_double_jac( const ecp_group *grp, ecp_ptjac *R,
const ecp_ptjac *P )
{
- int ret = 0;
+ int ret;
mpi T1, T2, T3, X, Y, Z;
if( mpi_cmp_int( &P->Z, 0 ) == 0 )
@@ -508,17 +504,16 @@
mpi_init( &T1 ); mpi_init( &T2 ); mpi_init( &T3 );
mpi_init( &X ); mpi_init( &Y ); mpi_init( &Z );
- MPI_CHK( mpi_mul_mpi( &T1, &P->Z, &P->Z ) ); MOD_MUL( T1 );
- MPI_CHK( mpi_sub_mpi( &T2, &P->X, &T1 ) ); MOD_SUB( T2 );
- MPI_CHK( mpi_add_mpi( &T1, &P->X, &T1 ) ); MOD_ADD( T1 );
- MPI_CHK( mpi_mul_mpi( &T2, &T2, &T1 ) ); MOD_MUL( T2 );
- MPI_CHK( mpi_mul_int( &T2, &T2, 3 ) ); MOD_ADD( T2 );
- MPI_CHK( mpi_copy ( &Y, &P->Y ) );
- MPI_CHK( mpi_shift_l( &Y, 1 ) ); MOD_ADD( Y );
- MPI_CHK( mpi_mul_mpi( &Z, &Y, &P->Z ) ); MOD_MUL( Z );
- MPI_CHK( mpi_mul_mpi( &Y, &Y, &Y ) ); MOD_MUL( Y );
- MPI_CHK( mpi_mul_mpi( &T3, &Y, &P->X ) ); MOD_MUL( T3 );
- MPI_CHK( mpi_mul_mpi( &Y, &Y, &Y ) ); MOD_MUL( Y );
+ MPI_CHK( mpi_mul_mpi( &T1, &P->Z, &P->Z ) ); MOD_MUL( T1 );
+ MPI_CHK( mpi_sub_mpi( &T2, &P->X, &T1 ) ); MOD_SUB( T2 );
+ MPI_CHK( mpi_add_mpi( &T1, &P->X, &T1 ) ); MOD_ADD( T1 );
+ MPI_CHK( mpi_mul_mpi( &T2, &T2, &T1 ) ); MOD_MUL( T2 );
+ MPI_CHK( mpi_mul_int( &T2, &T2, 3 ) ); MOD_ADD( T2 );
+ MPI_CHK( mpi_mul_int( &Y, &P->Y, 2 ) ); MOD_ADD( Y );
+ MPI_CHK( mpi_mul_mpi( &Z, &Y, &P->Z ) ); MOD_MUL( Z );
+ MPI_CHK( mpi_mul_mpi( &Y, &Y, &Y ) ); MOD_MUL( Y );
+ MPI_CHK( mpi_mul_mpi( &T3, &Y, &P->X ) ); MOD_MUL( T3 );
+ MPI_CHK( mpi_mul_mpi( &Y, &Y, &Y ) ); MOD_MUL( Y );
/*
* For Y = Y / 2 mod p, we must make sure that Y is even before
@@ -528,13 +523,12 @@
MPI_CHK( mpi_add_mpi( &Y, &Y, &grp->P ) );
MPI_CHK( mpi_shift_r( &Y, 1 ) );
- MPI_CHK( mpi_mul_mpi( &X, &T2, &T2 ) ); MOD_MUL( X );
- MPI_CHK( mpi_copy ( &T1, &T3 ) );
- MPI_CHK( mpi_shift_l( &T1, 1 ) ); MOD_ADD( T1 );
- MPI_CHK( mpi_sub_mpi( &X, &X, &T1 ) ); MOD_SUB( X );
- MPI_CHK( mpi_sub_mpi( &T1, &T3, &X ) ); MOD_SUB( T1 );
- MPI_CHK( mpi_mul_mpi( &T1, &T1, &T2 ) ); MOD_MUL( T1 );
- MPI_CHK( mpi_sub_mpi( &Y, &T1, &Y ) ); MOD_SUB( Y );
+ MPI_CHK( mpi_mul_mpi( &X, &T2, &T2 ) ); MOD_MUL( X );
+ MPI_CHK( mpi_mul_int( &T1, &T3, 2 ) ); MOD_ADD( T1 );
+ MPI_CHK( mpi_sub_mpi( &X, &X, &T1 ) ); MOD_SUB( X );
+ MPI_CHK( mpi_sub_mpi( &T1, &T3, &X ) ); MOD_SUB( T1 );
+ MPI_CHK( mpi_mul_mpi( &T1, &T1, &T2 ) ); MOD_MUL( T1 );
+ MPI_CHK( mpi_sub_mpi( &Y, &T1, &Y ) ); MOD_SUB( Y );
MPI_CHK( mpi_copy( &R->X, &X ) );
MPI_CHK( mpi_copy( &R->Y, &Y ) );
@@ -554,7 +548,7 @@
static int ecp_add_mixed( const ecp_group *grp, ecp_ptjac *R,
const ecp_ptjac *P, const ecp_point *Q )
{
- int ret = 0;
+ int ret;
mpi T1, T2, T3, T4, X, Y, Z;
/*
@@ -569,12 +563,12 @@
mpi_init( &T1 ); mpi_init( &T2 ); mpi_init( &T3 ); mpi_init( &T4 );
mpi_init( &X ); mpi_init( &Y ); mpi_init( &Z );
- MPI_CHK( mpi_mul_mpi( &T1, &P->Z, &P->Z ) ); MOD_MUL( T1 );
- MPI_CHK( mpi_mul_mpi( &T2, &T1, &P->Z ) ); MOD_MUL( T2 );
- MPI_CHK( mpi_mul_mpi( &T1, &T1, &Q->X ) ); MOD_MUL( T1 );
- MPI_CHK( mpi_mul_mpi( &T2, &T2, &Q->Y ) ); MOD_MUL( T2 );
- MPI_CHK( mpi_sub_mpi( &T1, &T1, &P->X ) ); MOD_SUB( T1 );
- MPI_CHK( mpi_sub_mpi( &T2, &T2, &P->Y ) ); MOD_SUB( T2 );
+ MPI_CHK( mpi_mul_mpi( &T1, &P->Z, &P->Z ) ); MOD_MUL( T1 );
+ MPI_CHK( mpi_mul_mpi( &T2, &T1, &P->Z ) ); MOD_MUL( T2 );
+ MPI_CHK( mpi_mul_mpi( &T1, &T1, &Q->X ) ); MOD_MUL( T1 );
+ MPI_CHK( mpi_mul_mpi( &T2, &T2, &Q->Y ) ); MOD_MUL( T2 );
+ MPI_CHK( mpi_sub_mpi( &T1, &T1, &P->X ) ); MOD_SUB( T1 );
+ MPI_CHK( mpi_sub_mpi( &T2, &T2, &P->Y ) ); MOD_SUB( T2 );
if( mpi_cmp_int( &T1, 0 ) == 0 )
{
@@ -590,18 +584,18 @@
}
}
- MPI_CHK( mpi_mul_mpi( &Z, &P->Z, &T1 ) ); MOD_MUL( Z );
- MPI_CHK( mpi_mul_mpi( &T3, &T1, &T1 ) ); MOD_MUL( T3 );
- MPI_CHK( mpi_mul_mpi( &T4, &T3, &T1 ) ); MOD_MUL( T4 );
- MPI_CHK( mpi_mul_mpi( &T3, &T3, &P->X ) ); MOD_MUL( T3 );
- MPI_CHK( mpi_mul_int( &T1, &T3, 2 ) ); MOD_ADD( T1 );
- MPI_CHK( mpi_mul_mpi( &X, &T2, &T2 ) ); MOD_MUL( X );
- MPI_CHK( mpi_sub_mpi( &X, &X, &T1 ) ); MOD_SUB( X );
- MPI_CHK( mpi_sub_mpi( &X, &X, &T4 ) ); MOD_SUB( X );
- MPI_CHK( mpi_sub_mpi( &T3, &T3, &X ) ); MOD_SUB( T3 );
- MPI_CHK( mpi_mul_mpi( &T3, &T3, &T2 ) ); MOD_MUL( T3 );
- MPI_CHK( mpi_mul_mpi( &T4, &T4, &P->Y ) ); MOD_MUL( T4 );
- MPI_CHK( mpi_sub_mpi( &Y, &T3, &T4 ) ); MOD_SUB( Y );
+ MPI_CHK( mpi_mul_mpi( &Z, &P->Z, &T1 ) ); MOD_MUL( Z );
+ MPI_CHK( mpi_mul_mpi( &T3, &T1, &T1 ) ); MOD_MUL( T3 );
+ MPI_CHK( mpi_mul_mpi( &T4, &T3, &T1 ) ); MOD_MUL( T4 );
+ MPI_CHK( mpi_mul_mpi( &T3, &T3, &P->X ) ); MOD_MUL( T3 );
+ MPI_CHK( mpi_mul_int( &T1, &T3, 2 ) ); MOD_ADD( T1 );
+ MPI_CHK( mpi_mul_mpi( &X, &T2, &T2 ) ); MOD_MUL( X );
+ MPI_CHK( mpi_sub_mpi( &X, &X, &T1 ) ); MOD_SUB( X );
+ MPI_CHK( mpi_sub_mpi( &X, &X, &T4 ) ); MOD_SUB( X );
+ MPI_CHK( mpi_sub_mpi( &T3, &T3, &X ) ); MOD_SUB( T3 );
+ MPI_CHK( mpi_mul_mpi( &T3, &T3, &T2 ) ); MOD_MUL( T3 );
+ MPI_CHK( mpi_mul_mpi( &T4, &T4, &P->Y ) ); MOD_MUL( T4 );
+ MPI_CHK( mpi_sub_mpi( &Y, &T3, &T4 ) ); MOD_SUB( Y );
MPI_CHK( mpi_copy( &R->X, &X ) );
MPI_CHK( mpi_copy( &R->Y, &Y ) );
@@ -621,7 +615,7 @@
int ecp_add( const ecp_group *grp, ecp_point *R,
const ecp_point *P, const ecp_point *Q )
{
- int ret = 0;
+ int ret;
ecp_ptjac J;
ecp_ptjac_init( &J );
@@ -643,20 +637,20 @@
int ecp_mul( const ecp_group *grp, ecp_point *R,
const mpi *m, const ecp_point *P )
{
- int ret = 0;
+ int ret;
size_t pos;
ecp_ptjac Q[2];
- ecp_ptjac_init( &Q[0] ); ecp_ptjac_init( &Q[1] );
-
/*
* The general method works only for m >= 1
*/
if( mpi_cmp_int( m, 0 ) == 0 ) {
ecp_set_zero( R );
- goto cleanup;
+ return( 0 );
}
+ ecp_ptjac_init( &Q[0] ); ecp_ptjac_init( &Q[1] );
+
ecp_ptjac_set_zero( &Q[0] );
for( pos = mpi_msb( m ) - 1 ; ; pos-- )