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author | Dmitry Kasatkin <dmitry.kasatkin@intel.com> | 2011-08-31 13:05:16 +0200 |
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committer | Dmitry Kasatkin <dmitry.kasatkin@intel.com> | 2011-11-09 10:45:22 +0100 |
commit | cdec9cb5167ab1113ba9c58e395f664d9d3f9acb (patch) | |
tree | 7d9a4ab3e86b937354d0151a24d412ea8d56ad43 /lib/mpi/generic_mpih-lshift.c | |
parent | Linux 3.2-rc1 (diff) | |
download | linux-cdec9cb5167ab1113ba9c58e395f664d9d3f9acb.tar.xz linux-cdec9cb5167ab1113ba9c58e395f664d9d3f9acb.zip |
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 <dmitry.kasatkin@intel.com>
Diffstat (limited to 'lib/mpi/generic_mpih-lshift.c')
-rw-r--r-- | lib/mpi/generic_mpih-lshift.c | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/lib/mpi/generic_mpih-lshift.c b/lib/mpi/generic_mpih-lshift.c new file mode 100644 index 000000000000..86318927231a --- /dev/null +++ b/lib/mpi/generic_mpih-lshift.c @@ -0,0 +1,63 @@ +/* mpihelp-lshift.c - MPI helper functions + * Copyright (C) 1994, 1996, 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" + +/* Shift U (pointed to by UP and USIZE digits long) CNT bits to the left + * and store the USIZE least significant digits of the result at WP. + * Return the bits shifted out from the most significant digit. + * + * Argument constraints: + * 1. 0 < CNT < BITS_PER_MP_LIMB + * 2. If the result is to be written over the input, WP must be >= UP. + */ + +mpi_limb_t +mpihelp_lshift(mpi_ptr_t wp, mpi_ptr_t up, mpi_size_t usize, unsigned int cnt) +{ + mpi_limb_t high_limb, low_limb; + unsigned sh_1, sh_2; + mpi_size_t i; + mpi_limb_t retval; + + sh_1 = cnt; + wp += 1; + sh_2 = BITS_PER_MPI_LIMB - sh_1; + i = usize - 1; + low_limb = up[i]; + retval = low_limb >> sh_2; + high_limb = low_limb; + while (--i >= 0) { + low_limb = up[i]; + wp[i] = (high_limb << sh_1) | (low_limb >> sh_2); + high_limb = low_limb; + } + wp[i] = high_limb << sh_1; + + return retval; +} |