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more minor improvement

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This commit is contained in:
NIIBE Yutaka
2013-12-16 16:47:25 +09:00
parent af3fc992b9
commit 4ef82f0a49
1 changed files with 12 additions and 13 deletions
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25
polarssl/library/bignum.c
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@@ -1045,7 +1045,7 @@ t_uint mpi_mul_hlp( size_t i, const t_uint *s, t_uint *d, t_uint b )
t++; t++;
*d += c; c = ( *d < c ); d++; *d += c; c = ( *d < c );
return c; return c;
} }
@@ -1463,7 +1463,7 @@ int mpi_exp_mod( mpi *X, const mpi *A, const mpi *E, const mpi *N, mpi *_RR )
size_t i, j, nblimbs; size_t i, j, nblimbs;
size_t bufsize, nbits; size_t bufsize, nbits;
t_uint ei, mm, state; t_uint ei, mm, state;
mpi RR, RR0, T, W[ 2 << POLARSSL_MPI_WINDOW_SIZE ], Apos; mpi RR, T, W[ 2 << POLARSSL_MPI_WINDOW_SIZE ], Apos;
int neg; int neg;
if( mpi_cmp_int( N, 0 ) < 0 || ( N->p[0] & 1 ) == 0 ) if( mpi_cmp_int( N, 0 ) < 0 || ( N->p[0] & 1 ) == 0 )
@@ -1476,7 +1476,7 @@ int mpi_exp_mod( mpi *X, const mpi *A, const mpi *E, const mpi *N, mpi *_RR )
* Init temps and window size * Init temps and window size
*/ */
mpi_montg_init( &mm, N ); mpi_montg_init( &mm, N );
mpi_init( &RR ); mpi_init( &RR0 ); mpi_init( &T ); mpi_init( &RR ); mpi_init( &T );
memset( W, 0, sizeof( W ) ); memset( W, 0, sizeof( W ) );
i = mpi_msb( E ); i = mpi_msb( E );
@@ -1488,10 +1488,9 @@ int mpi_exp_mod( mpi *X, const mpi *A, const mpi *E, const mpi *N, mpi *_RR )
wsize = POLARSSL_MPI_WINDOW_SIZE; wsize = POLARSSL_MPI_WINDOW_SIZE;
j = N->n; j = N->n;
MPI_CHK( mpi_grow( X, j ) ); MPI_CHK( mpi_grow( X, N->n ) );
MPI_CHK( mpi_grow( &W[1], j ) ); MPI_CHK( mpi_grow( &W[1], N->n ) );
MPI_CHK( mpi_grow( &T, j * 2 ) ); MPI_CHK( mpi_grow( &T, N->n * 2 ) ); /* T = 0 here. */
memset( T.p, 0, j * ciL ); /* Clear the lower half of T. */
/* /*
* Compensate for negative A (and correct at the end) * Compensate for negative A (and correct at the end)
@@ -1511,14 +1510,14 @@ int mpi_exp_mod( mpi *X, const mpi *A, const mpi *E, const mpi *N, mpi *_RR )
*/ */
if( _RR == NULL || _RR->p == NULL ) if( _RR == NULL || _RR->p == NULL )
{ {
MPI_CHK( mpi_lset( &RR0, 1 ) ); /* T->p is all zero here. */
MPI_CHK( mpi_shift_l( &RR0, N->n * 2 * biL ) ); mpi_sub_hlp( N->n, N->p, T.p + N->n);
MPI_CHK( mpi_mod_mpi( &RR0, &RR0, N ) ); MPI_CHK( mpi_mod_mpi( &RR, &T, N ) );
MPI_CHK( mpi_copy( &RR, &RR0 ) ); /* Shrink to size of N. */
MPI_CHK( mpi_grow( &RR, N->n ) );
if( _RR != NULL ) if( _RR != NULL )
memcpy( _RR, &RR, sizeof( mpi ) ); memcpy( _RR, &RR, sizeof( mpi ) );
/* The condition of "the lower half of T is all zero" is kept. */
} }
else else
memcpy( &RR, _RR, sizeof( mpi ) ); memcpy( &RR, _RR, sizeof( mpi ) );
@@ -1663,7 +1662,7 @@ cleanup:
for( i = (one << (wsize - 1)); i < (one << wsize); i++ ) for( i = (one << (wsize - 1)); i < (one << wsize); i++ )
mpi_free( &W[i] ); mpi_free( &W[i] );
mpi_free( &RR0 ); mpi_free( &W[1] ); mpi_free( &T ); mpi_free( &Apos ); mpi_free( &W[1] ); mpi_free( &T ); mpi_free( &Apos );
if( _RR == NULL ) if( _RR == NULL )
mpi_free( &RR ); mpi_free( &RR );