From cdec9cb5167ab1113ba9c58e395f664d9d3f9acb Mon Sep 17 00:00:00 2001 From: Dmitry Kasatkin Date: Wed, 31 Aug 2011 14:05:16 +0300 Subject: crypto: GnuPG based MPI lib - source files (part 1) 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. Signed-off-by: Dmitry Kasatkin --- lib/mpi/generic_mpih-sub1.c | 60 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) create mode 100644 lib/mpi/generic_mpih-sub1.c (limited to 'lib/mpi/generic_mpih-sub1.c') diff --git a/lib/mpi/generic_mpih-sub1.c b/lib/mpi/generic_mpih-sub1.c new file mode 100644 index 000000000000..5d98ab7d6853 --- /dev/null +++ b/lib/mpi/generic_mpih-sub1.c @@ -0,0 +1,60 @@ +/* mpihelp-add_2.c - MPI helper functions + * Copyright (C) 1994, 1996, 1997, 1998, 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 + * + * Note: This code is heavily based on the GNU MP Library. + * Actually it's the same code with only minor changes in the + * way the data is stored; this is to support the abstraction + * of an optional secure memory allocation which may be used + * to avoid revealing of sensitive data due to paging etc. + * The GNU MP Library itself is published under the LGPL; + * however I decided to publish this code under the plain GPL. + */ + +#include "mpi-internal.h" +#include "longlong.h" + +mpi_limb_t +mpihelp_sub_n(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, + mpi_ptr_t s2_ptr, mpi_size_t size) +{ + mpi_limb_t x, y, cy; + mpi_size_t j; + + /* The loop counter and index J goes from -SIZE to -1. This way + the loop becomes faster. */ + j = -size; + + /* Offset the base pointers to compensate for the negative indices. */ + s1_ptr -= j; + s2_ptr -= j; + res_ptr -= j; + + cy = 0; + do { + y = s2_ptr[j]; + x = s1_ptr[j]; + y += cy; /* add previous carry to subtrahend */ + cy = y < cy; /* get out carry from that addition */ + y = x - y; /* main subtract */ + cy += y > x; /* get out carry from the subtract, combine */ + res_ptr[j] = y; + } while (++j); + + return cy; +} -- cgit v1.2.3