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author | Dmitry Kasatkin <dmitry.kasatkin@intel.com> | 2011-11-07 15:16:37 +0200 |
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committer | Dmitry Kasatkin <dmitry.kasatkin@intel.com> | 2011-11-09 11:47:26 +0200 |
commit | 7e8dec918ef8e0f68b4937c3c50fa57002077a4d (patch) | |
tree | a17d33fa54fcb18c335b36c4550b889b206015f4 /lib/mpi/mpi-mpow.c | |
parent | d9c46b184fcfd33c85a7dc48a653435a08e21f56 (diff) | |
download | op-kernel-dev-7e8dec918ef8e0f68b4937c3c50fa57002077a4d.zip op-kernel-dev-7e8dec918ef8e0f68b4937c3c50fa57002077a4d.tar.gz |
crypto: GnuPG based MPI lib - additional sources (part 4)
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>
Diffstat (limited to 'lib/mpi/mpi-mpow.c')
-rw-r--r-- | lib/mpi/mpi-mpow.c | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/lib/mpi/mpi-mpow.c b/lib/mpi/mpi-mpow.c new file mode 100644 index 0000000..4cc7593 --- /dev/null +++ b/lib/mpi/mpi-mpow.c @@ -0,0 +1,133 @@ +/* mpi-mpow.c - MPI functions + * Copyright (C) 1998, 1999, 2000 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" +#include "longlong.h" + +static int build_index(const MPI *exparray, int k, int i, int t) +{ + int j, bitno; + int index = 0; + + bitno = t - i; + for (j = k - 1; j >= 0; j--) { + index <<= 1; + if (mpi_test_bit(exparray[j], bitno)) + index |= 1; + } + return index; +} + +/**************** + * RES = (BASE[0] ^ EXP[0]) * (BASE[1] ^ EXP[1]) * ... * mod M + */ +int mpi_mulpowm(MPI res, MPI *basearray, MPI *exparray, MPI m) +{ + int rc = -ENOMEM; + int k; /* number of elements */ + int t; /* bit size of largest exponent */ + int i, j, idx; + MPI *G = NULL; /* table with precomputed values of size 2^k */ + MPI tmp = NULL; + + for (k = 0; basearray[k]; k++) + ; + if (!k) { + pr_emerg("mpi_mulpowm: assert(k) failed\n"); + BUG(); + } + for (t = 0, i = 0; (tmp = exparray[i]); i++) { + j = mpi_get_nbits(tmp); + if (j > t) + t = j; + } + if (i != k) { + pr_emerg("mpi_mulpowm: assert(i==k) failed\n"); + BUG(); + } + if (!t) { + pr_emerg("mpi_mulpowm: assert(t) failed\n"); + BUG(); + } + if (k >= 10) { + pr_emerg("mpi_mulpowm: assert(k<10) failed\n"); + BUG(); + } + + G = kzalloc((1 << k) * sizeof *G, GFP_KERNEL); + if (!G) + goto nomem; + + /* and calculate */ + tmp = mpi_alloc(mpi_get_nlimbs(m) + 1); + if (!tmp) + goto nomem; + if (mpi_set_ui(res, 1) < 0) + goto nomem; + for (i = 1; i <= t; i++) { + if (mpi_mulm(tmp, res, res, m) < 0) + goto nomem; + idx = build_index(exparray, k, i, t); + if (!(idx >= 0 && idx < (1 << k))) { + pr_emerg("mpi_mulpowm: assert(idx >= 0 && idx < (1<<k)) failed\n"); + BUG(); + } + if (!G[idx]) { + if (!idx) { + G[0] = mpi_alloc_set_ui(1); + if (!G[0]) + goto nomem; + } else { + for (j = 0; j < k; j++) { + if ((idx & (1 << j))) { + if (!G[idx]) { + if (mpi_copy + (&G[idx], + basearray[j]) < 0) + goto nomem; + } else { + if (mpi_mulm + (G[idx], G[idx], + basearray[j], + m) < 0) + goto nomem; + } + } + } + if (!G[idx]) { + G[idx] = mpi_alloc(0); + if (!G[idx]) + goto nomem; + } + } + } + if (mpi_mulm(res, tmp, G[idx], m) < 0) + goto nomem; + } + + rc = 0; +nomem: + /* cleanup */ + mpi_free(tmp); + for (i = 0; i < (1 << k); i++) + mpi_free(G[i]); + kfree(G); + return rc; +} |