aboutsummaryrefslogtreecommitdiff
path: root/lib/mpi/generic_mpih-lshift.c
diff options
context:
space:
mode:
authorDmitry Kasatkin <dmitry.kasatkin@intel.com>2011-08-31 14:05:16 +0300
committerDmitry Kasatkin <dmitry.kasatkin@intel.com>2011-11-09 11:45:22 +0200
commitcdec9cb5167ab1113ba9c58e395f664d9d3f9acb (patch)
tree7d9a4ab3e86b937354d0151a24d412ea8d56ad43 /lib/mpi/generic_mpih-lshift.c
parent1ea6b8f48918282bdca0b32a34095504ee65bab5 (diff)
downloadlinux-linaro-stable-cdec9cb5167ab1113ba9c58e395f664d9d3f9acb.tar.gz
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.c63
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;
+}