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- Fixed a bug in mpi_gcd() that prevented correct funtioning when both input numbers are even.

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This commit is contained in:
Paul Bakker 2009-01-29 22:24:33 +00:00
parent 785a9eeece
commit 4e0d7ca233
2 changed files with 54 additions and 6 deletions
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8
ChangeLog
View file

@ -1,5 +1,13 @@
PolarSSL ChangeLog
= Version 0.10.2 released on 2009-XXXX
* Fixed a bug in mpi_gcd() so that it also works when both
input numbers are even and added testcases to check
(found by Pierre Habouzit)
= Version 0.10.1 released on 2009-01-25
* Added BSD License
= Version 0.10.0 released on 2009-01-12
* Migrated XySSL to PolarSSL
* Added XTEA symmetric cipher

52
library/bignum.c
View file

@ -1478,21 +1478,29 @@ cleanup:
*/
int mpi_gcd( mpi *G, mpi *A, mpi *B )
{
int ret;
int ret, lz, lzt;
mpi TG, TA, TB;
mpi_init( &TG, &TA, &TB, NULL );
MPI_CHK( mpi_lset( &TG, 1 ) );
MPI_CHK( mpi_copy( &TA, A ) );
MPI_CHK( mpi_copy( &TB, B ) );
lz = mpi_lsb( &TA );
lzt = mpi_lsb( &TB );
if ( lzt < lz )
lz = lzt;
MPI_CHK( mpi_shift_r( &TA, lz ) );
MPI_CHK( mpi_shift_r( &TB, lz ) );
TA.s = TB.s = 1;
while( mpi_cmp_int( &TA, 0 ) != 0 )
{
while( ( TA.p[0] & 1 ) == 0 ) MPI_CHK( mpi_shift_r( &TA, 1 ) );
while( ( TB.p[0] & 1 ) == 0 ) MPI_CHK( mpi_shift_r( &TB, 1 ) );
MPI_CHK( mpi_shift_r( &TA, mpi_lsb( &TA ) ) );
MPI_CHK( mpi_shift_r( &TB, mpi_lsb( &TB ) ) );
if( mpi_cmp_mpi( &TA, &TB ) >= 0 )
{
@ -1506,7 +1514,8 @@ int mpi_gcd( mpi *G, mpi *A, mpi *B )
}
}
MPI_CHK( mpi_mul_mpi( G, &TG, &TB ) );
MPI_CHK( mpi_shift_l( &TB, lz ) );
MPI_CHK( mpi_copy( G, &TB ) );
cleanup:
@ -1820,12 +1829,21 @@ cleanup:
#if defined(POLARSSL_SELF_TEST)
#define GCD_PAIR_COUNT 3
static const int gcd_pairs[GCD_PAIR_COUNT][3] =
{
{ 693, 609, 21 },
{ 1764, 868, 28 },
{ 768454923, 542167814, 1 }
};
/*
* Checkup routine
*/
int mpi_self_test( int verbose )
{
int ret;
int ret, i;
mpi A, E, N, X, Y, U, V;
mpi_init( &A, &E, &N, &X, &Y, &U, &V, NULL );
@ -1939,6 +1957,28 @@ int mpi_self_test( int verbose )
if( verbose != 0 )
printf( "passed\n" );
if( verbose != 0 )
printf( " MPI test #5 (simple gcd): " );
for ( i = 0; i < GCD_PAIR_COUNT; i++)
{
MPI_CHK( mpi_lset( &X, gcd_pairs[i][0] ) );
MPI_CHK( mpi_lset( &Y, gcd_pairs[i][1] ) );
MPI_CHK( mpi_gcd( &A, &X, &Y ) );
if( mpi_cmp_int( &A, gcd_pairs[i][2] ) != 0 )
{
if( verbose != 0 )
printf( "failed at %d\n", i );
return( 1 );
}
}
if( verbose != 0 )
printf( "passed\n" );
cleanup:
if( ret != 0 && verbose != 0 )