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-rw-r--r--plugins/MirOTR/libgcrypt-1.4.6/mpi/mpi-pow.c326
1 files changed, 326 insertions, 0 deletions
diff --git a/plugins/MirOTR/libgcrypt-1.4.6/mpi/mpi-pow.c b/plugins/MirOTR/libgcrypt-1.4.6/mpi/mpi-pow.c
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+++ b/plugins/MirOTR/libgcrypt-1.4.6/mpi/mpi-pow.c
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+/* mpi-pow.c - MPI functions for exponentiation
+ * Copyright (C) 1994, 1996, 1998, 2000, 2002
+ * 2003 Free Software Foundation, Inc.
+ *
+ * This file is part of Libgcrypt.
+ *
+ * Libgcrypt is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * Libgcrypt 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * 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.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "mpi-internal.h"
+#include "longlong.h"
+
+
+/****************
+ * RES = BASE ^ EXPO mod MOD
+ */
+void
+gcry_mpi_powm (gcry_mpi_t res,
+ gcry_mpi_t base, gcry_mpi_t expo, gcry_mpi_t mod)
+{
+ /* Pointer to the limbs of the arguments, their size and signs. */
+ mpi_ptr_t rp, ep, mp, bp;
+ mpi_size_t esize, msize, bsize, rsize;
+ int msign, bsign, rsign;
+ /* Flags telling the secure allocation status of the arguments. */
+ int esec, msec, bsec, rsec;
+ /* Size of the result including space for temporary values. */
+ mpi_size_t size;
+ /* Helper. */
+ int mod_shift_cnt;
+ int negative_result;
+ mpi_ptr_t mp_marker = NULL;
+ mpi_ptr_t bp_marker = NULL;
+ mpi_ptr_t ep_marker = NULL;
+ mpi_ptr_t xp_marker = NULL;
+ unsigned int mp_nlimbs = 0;
+ unsigned int bp_nlimbs = 0;
+ unsigned int ep_nlimbs = 0;
+ unsigned int xp_nlimbs = 0;
+ mpi_ptr_t tspace = NULL;
+ mpi_size_t tsize = 0;
+
+
+ esize = expo->nlimbs;
+ msize = mod->nlimbs;
+ size = 2 * msize;
+ msign = mod->sign;
+
+ esec = mpi_is_secure(expo);
+ msec = mpi_is_secure(mod);
+ bsec = mpi_is_secure(base);
+ rsec = mpi_is_secure(res);
+
+ rp = res->d;
+ ep = expo->d;
+
+ if (!msize)
+ msize = 1 / msize; /* Provoke a signal. */
+
+ if (!esize)
+ {
+ /* Exponent is zero, result is 1 mod MOD, i.e., 1 or 0 depending
+ on if MOD equals 1. */
+ rp[0] = 1;
+ res->nlimbs = (msize == 1 && mod->d[0] == 1) ? 0 : 1;
+ res->sign = 0;
+ goto leave;
+ }
+
+ /* Normalize MOD (i.e. make its most significant bit set) as
+ required by mpn_divrem. This will make the intermediate values
+ in the calculation slightly larger, but the correct result is
+ obtained after a final reduction using the original MOD value. */
+ mp_nlimbs = msec? msize:0;
+ mp = mp_marker = mpi_alloc_limb_space(msize, msec);
+ count_leading_zeros (mod_shift_cnt, mod->d[msize-1]);
+ if (mod_shift_cnt)
+ _gcry_mpih_lshift (mp, mod->d, msize, mod_shift_cnt);
+ else
+ MPN_COPY( mp, mod->d, msize );
+
+ bsize = base->nlimbs;
+ bsign = base->sign;
+ if (bsize > msize)
+ {
+ /* The base is larger than the module. Reduce it.
+
+ Allocate (BSIZE + 1) with space for remainder and quotient.
+ (The quotient is (bsize - msize + 1) limbs.) */
+ bp_nlimbs = bsec ? (bsize + 1):0;
+ bp = bp_marker = mpi_alloc_limb_space( bsize + 1, bsec );
+ MPN_COPY ( bp, base->d, bsize );
+ /* We don't care about the quotient, store it above the
+ * remainder, at BP + MSIZE. */
+ _gcry_mpih_divrem( bp + msize, 0, bp, bsize, mp, msize );
+ bsize = msize;
+ /* Canonicalize the base, since we are going to multiply with it
+ quite a few times. */
+ MPN_NORMALIZE( bp, bsize );
+ }
+ else
+ bp = base->d;
+
+ if (!bsize)
+ {
+ res->nlimbs = 0;
+ res->sign = 0;
+ goto leave;
+ }
+
+
+ /* Make BASE, EXPO and MOD not overlap with RES. */
+ if ( rp == bp )
+ {
+ /* RES and BASE are identical. Allocate temp. space for BASE. */
+ gcry_assert (!bp_marker);
+ bp_nlimbs = bsec? bsize:0;
+ bp = bp_marker = mpi_alloc_limb_space( bsize, bsec );
+ MPN_COPY(bp, rp, bsize);
+ }
+ if ( rp == ep )
+ {
+ /* RES and EXPO are identical. Allocate temp. space for EXPO. */
+ ep_nlimbs = esec? esize:0;
+ ep = ep_marker = mpi_alloc_limb_space( esize, esec );
+ MPN_COPY(ep, rp, esize);
+ }
+ if ( rp == mp )
+ {
+ /* RES and MOD are identical. Allocate temporary space for MOD.*/
+ gcry_assert (!mp_marker);
+ mp_nlimbs = msec?msize:0;
+ mp = mp_marker = mpi_alloc_limb_space( msize, msec );
+ MPN_COPY(mp, rp, msize);
+ }
+
+ /* Copy base to the result. */
+ if (res->alloced < size)
+ {
+ mpi_resize (res, size);
+ rp = res->d;
+ }
+ MPN_COPY ( rp, bp, bsize );
+ rsize = bsize;
+ rsign = bsign;
+
+ /* Main processing. */
+ {
+ mpi_size_t i;
+ mpi_ptr_t xp;
+ int c;
+ mpi_limb_t e;
+ mpi_limb_t carry_limb;
+ struct karatsuba_ctx karactx;
+
+ xp_nlimbs = msec? (2 * (msize + 1)):0;
+ xp = xp_marker = mpi_alloc_limb_space( 2 * (msize + 1), msec );
+
+ memset( &karactx, 0, sizeof karactx );
+ negative_result = (ep[0] & 1) && base->sign;
+
+ i = esize - 1;
+ e = ep[i];
+ count_leading_zeros (c, e);
+ e = (e << c) << 1; /* Shift the expo bits to the left, lose msb. */
+ c = BITS_PER_MPI_LIMB - 1 - c;
+
+ /* Main loop.
+
+ Make the result be pointed to alternately by XP and RP. This
+ helps us avoid block copying, which would otherwise be
+ necessary with the overlap restrictions of
+ _gcry_mpih_divmod. With 50% probability the result after this
+ loop will be in the area originally pointed by RP (==RES->d),
+ and with 50% probability in the area originally pointed to by XP. */
+ for (;;)
+ {
+ while (c)
+ {
+ mpi_ptr_t tp;
+ mpi_size_t xsize;
+
+ /*mpih_mul_n(xp, rp, rp, rsize);*/
+ if ( rsize < KARATSUBA_THRESHOLD )
+ _gcry_mpih_sqr_n_basecase( xp, rp, rsize );
+ else
+ {
+ if ( !tspace )
+ {
+ tsize = 2 * rsize;
+ tspace = mpi_alloc_limb_space( tsize, 0 );
+ }
+ else if ( tsize < (2*rsize) )
+ {
+ _gcry_mpi_free_limb_space (tspace, 0);
+ tsize = 2 * rsize;
+ tspace = mpi_alloc_limb_space (tsize, 0 );
+ }
+ _gcry_mpih_sqr_n (xp, rp, rsize, tspace);
+ }
+
+ xsize = 2 * rsize;
+ if ( xsize > msize )
+ {
+ _gcry_mpih_divrem(xp + msize, 0, xp, xsize, mp, msize);
+ xsize = msize;
+ }
+
+ tp = rp; rp = xp; xp = tp;
+ rsize = xsize;
+
+ if ( (mpi_limb_signed_t)e < 0 )
+ {
+ /*mpih_mul( xp, rp, rsize, bp, bsize );*/
+ if( bsize < KARATSUBA_THRESHOLD )
+ _gcry_mpih_mul ( xp, rp, rsize, bp, bsize );
+ else
+ _gcry_mpih_mul_karatsuba_case (xp, rp, rsize, bp, bsize,
+ &karactx);
+
+ xsize = rsize + bsize;
+ if ( xsize > msize )
+ {
+ _gcry_mpih_divrem(xp + msize, 0, xp, xsize, mp, msize);
+ xsize = msize;
+ }
+
+ tp = rp; rp = xp; xp = tp;
+ rsize = xsize;
+ }
+ e <<= 1;
+ c--;
+ }
+
+ i--;
+ if ( i < 0 )
+ break;
+ e = ep[i];
+ c = BITS_PER_MPI_LIMB;
+ }
+
+ /* We shifted MOD, the modulo reduction argument, left
+ MOD_SHIFT_CNT steps. Adjust the result by reducing it with the
+ original MOD.
+
+ Also make sure the result is put in RES->d (where it already
+ might be, see above). */
+ if ( mod_shift_cnt )
+ {
+ carry_limb = _gcry_mpih_lshift( res->d, rp, rsize, mod_shift_cnt);
+ rp = res->d;
+ if ( carry_limb )
+ {
+ rp[rsize] = carry_limb;
+ rsize++;
+ }
+ }
+ else if (res->d != rp)
+ {
+ MPN_COPY (res->d, rp, rsize);
+ rp = res->d;
+ }
+
+ if ( rsize >= msize )
+ {
+ _gcry_mpih_divrem(rp + msize, 0, rp, rsize, mp, msize);
+ rsize = msize;
+ }
+
+ /* Remove any leading zero words from the result. */
+ if ( mod_shift_cnt )
+ _gcry_mpih_rshift( rp, rp, rsize, mod_shift_cnt);
+ MPN_NORMALIZE (rp, rsize);
+
+ _gcry_mpih_release_karatsuba_ctx (&karactx );
+ }
+
+ /* Fixup for negative results. */
+ if ( negative_result && rsize )
+ {
+ if ( mod_shift_cnt )
+ _gcry_mpih_rshift( mp, mp, msize, mod_shift_cnt);
+ _gcry_mpih_sub( rp, mp, msize, rp, rsize);
+ rsize = msize;
+ rsign = msign;
+ MPN_NORMALIZE(rp, rsize);
+ }
+ gcry_assert (res->d == rp);
+ res->nlimbs = rsize;
+ res->sign = rsign;
+
+ leave:
+ if (mp_marker)
+ _gcry_mpi_free_limb_space( mp_marker, mp_nlimbs );
+ if (bp_marker)
+ _gcry_mpi_free_limb_space( bp_marker, bp_nlimbs );
+ if (ep_marker)
+ _gcry_mpi_free_limb_space( ep_marker, ep_nlimbs );
+ if (xp_marker)
+ _gcry_mpi_free_limb_space( xp_marker, xp_nlimbs );
+ if (tspace)
+ _gcry_mpi_free_limb_space( tspace, 0 );
+}
+
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