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Small code cleanups

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Manuel Pégourié-Gonnard 2013-11-21 09:50:00 +01:00
parent ff27b7c968
commit edc1a1f482
1 changed files with 12 additions and 29 deletions
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41
library/ecp.c
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@ -1276,35 +1276,26 @@ static void ecp_comb_fixed( unsigned char x[], size_t d,
memset( x, 0, d+1 ); memset( x, 0, d+1 );
/* For x[0] use the classical comb value without adjustement */ /* First get the classical comb values (except for x_d = 0) */
for( j = 0; j < w; j++ ) for( i = 0; i < d; i++ )
x[0] |= mpi_get_bit( m, d * j ) << j;
c = 0;
for( i = 1; i < d; i++ )
{
/* Get the classical comb value */
for( j = 0; j < w; j++ ) for( j = 0; j < w; j++ )
x[i] |= mpi_get_bit( m, i + d * j ) << j; x[i] |= mpi_get_bit( m, i + d * j ) << j;
/* Now make sure x_1 .. x_d are odd */
c = 0;
for( i = 1; i <= d; i++ )
{
/* Add carry and update it */ /* Add carry and update it */
cc = x[i] & c; cc = x[i] & c;
x[i] = x[i] ^ c; x[i] = x[i] ^ c;
c = cc; c = cc;
/* Make sure x[i] is odd, avoiding if-branches */ /* Adjust if needed, avoiding branches */
adjust = 1 - ( x[i] & 0x01 ); adjust = 1 - ( x[i] & 0x01 );
c |= x[i] & ( x[i-1] * adjust ); c |= x[i] & ( x[i-1] * adjust );
x[i] = x[i] ^ ( x[i-1] * adjust ); x[i] = x[i] ^ ( x[i-1] * adjust );
x[i-1] |= adjust << 7; x[i-1] |= adjust << 7;
} }
/* Finish with the carry */
x[i] = c;
adjust = 1 - ( x[i] & 0x01 );
c |= x[i] & ( x[i-1] * adjust );
x[i] = x[i] ^ ( x[i-1] * adjust );
x[i-1] |= adjust << 7;
} }
/* /*
@ -1487,9 +1478,12 @@ int ecp_mul( ecp_group *grp, ecp_point *R,
/* /*
* Prepare precomputed points: if P == G we want to * Prepare precomputed points: if P == G we want to
* use grp->T if already initialized, or initiliaze it. * use grp->T if already initialized, or initialize it.
*/ */
if( ! p_eq_g || grp->T == NULL ) if( p_eq_g )
T = grp->T;
if( T == NULL )
{ {
T = (ecp_point *) polarssl_malloc( pre_len * sizeof( ecp_point ) ); T = (ecp_point *) polarssl_malloc( pre_len * sizeof( ecp_point ) );
if( T == NULL ) if( T == NULL )
@ -1509,17 +1503,6 @@ int ecp_mul( ecp_group *grp, ecp_point *R,
grp->T_size = pre_len; grp->T_size = pre_len;
} }
} }
else
{
T = grp->T;
/* Should never happen, but we want to be extra sure */
if( pre_len != grp->T_size )
{
ret = POLARSSL_ERR_ECP_BAD_INPUT_DATA;
goto cleanup;
}
}
/* /*
* Make sure M is odd (M = m + 1 or M = m + 2) * Make sure M is odd (M = m + 1 or M = m + 2)