7e8dec918e
Adds the multi-precision-integer maths library which was originally taken from GnuPG and ported to the kernel by (among others) David Howells. This version is taken from Fedora kernel 2.6.32-71.14.1.el6. The difference is that checkpatch reported errors and warnings have been fixed. This library is used to implemenet RSA digital signature verification used in IMA/EVM integrity protection subsystem. Due to patch size limitation, the patch is divided into 4 parts. This code is unnecessary for RSA digital signature verification, but for completeness it is included here and can be compiled, if CONFIG_MPILIB_EXTRA is enabled. Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
60 lines
1.5 KiB
C
60 lines
1.5 KiB
C
/* mpi-gcd.c - MPI functions
|
|
* Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
|
|
*
|
|
* This file is part of GnuPG.
|
|
*
|
|
* GnuPG is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* GnuPG is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
|
|
*/
|
|
|
|
#include "mpi-internal.h"
|
|
|
|
/****************
|
|
* Find the greatest common divisor G of A and B.
|
|
* Return: true if this 1, false in all other cases
|
|
*/
|
|
int mpi_gcd(MPI g, const MPI xa, const MPI xb)
|
|
{
|
|
MPI a = NULL, b = NULL;
|
|
|
|
if (mpi_copy(&a, xa) < 0)
|
|
goto nomem;
|
|
|
|
if (mpi_copy(&b, xb) < 0)
|
|
goto nomem;
|
|
|
|
/* TAOCP Vol II, 4.5.2, Algorithm A */
|
|
a->sign = 0;
|
|
b->sign = 0;
|
|
while (mpi_cmp_ui(b, 0)) {
|
|
if (mpi_fdiv_r(g, a, b) < 0) /* g used as temorary variable */
|
|
goto nomem;
|
|
if (mpi_set(a, b) < 0)
|
|
goto nomem;
|
|
if (mpi_set(b, g) < 0)
|
|
goto nomem;
|
|
}
|
|
if (mpi_set(g, a) < 0)
|
|
goto nomem;
|
|
|
|
mpi_free(a);
|
|
mpi_free(b);
|
|
return !mpi_cmp_ui(g, 1);
|
|
|
|
nomem:
|
|
mpi_free(a);
|
|
mpi_free(b);
|
|
return -ENOMEM;
|
|
}
|