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author | Werner Koch <[email protected]> | 2000-12-19 17:20:22 +0000 |
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committer | Werner Koch <[email protected]> | 2000-12-19 17:20:22 +0000 |
commit | 07ca4eaa9d8df67acdccc86c782bcef685d49e2c (patch) | |
tree | 2876cad5493c5f4efa6c85e591dbe7cc26abadf0 /mpi/mpi-mpow.c | |
parent | About to release 1.1.2 (diff) | |
download | gnupg-07ca4eaa9d8df67acdccc86c782bcef685d49e2c.tar.gz gnupg-07ca4eaa9d8df67acdccc86c782bcef685d49e2c.zip |
Removed files from the HEAD revision, because they are now in another
repository
Diffstat (limited to 'mpi/mpi-mpow.c')
-rw-r--r-- | mpi/mpi-mpow.c | 222 |
1 files changed, 0 insertions, 222 deletions
diff --git a/mpi/mpi-mpow.c b/mpi/mpi-mpow.c deleted file mode 100644 index 556f7e116..000000000 --- a/mpi/mpi-mpow.c +++ /dev/null @@ -1,222 +0,0 @@ -/* mpi-mpow.c - MPI functions - * Copyright (C) 1998, 1999 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 <config.h> -#include <stdio.h> -#include <stdlib.h> -#include "mpi-internal.h" -#include "longlong.h" -#include <assert.h> - -/* Barrett is slower than the classical way. It can be tweaked by - * using partial multiplications - */ -/*#define USE_BARRETT*/ - - - -#ifdef USE_BARRETT -static void barrett_mulm( MPI w, MPI u, MPI v, MPI m, MPI y, int k, MPI r1, MPI r2 ); -static MPI init_barrett( MPI m, int *k, MPI *r1, MPI *r2 ); -static int calc_barrett( MPI r, MPI x, MPI m, MPI y, int k, MPI r1, MPI r2 ); -#else -#define barrett_mulm( w, u, v, m, y, k, r1, r2 ) mpi_mulm( (w), (u), (v), (m) ) -#endif - - -static int -build_index( MPI *exparray, int k, int i, int t ) -{ - int j, bitno; - int idx = 0; - - bitno = t-i; - for(j=k-1; j >= 0; j-- ) { - idx <<= 1; - if( mpi_test_bit( exparray[j], bitno ) ) - idx |= 1; - } - /*log_debug("t=%d i=%d idx=%d\n", t, i, idx );*/ - return idx; -} - -/**************** - * RES = (BASE[0] ^ EXP[0]) * (BASE[1] ^ EXP[1]) * ... * mod M - */ -void -mpi_mulpowm( MPI res, MPI *basearray, MPI *exparray, MPI m) -{ - int k; /* number of elements */ - int t; /* bit size of largest exponent */ - int i, j, idx; - MPI *G; /* table with precomputed values of size 2^k */ - MPI tmp; - #ifdef USE_BARRETT - MPI barrett_y, barrett_r1, barrett_r2; - int barrett_k; - #endif - - for(k=0; basearray[k]; k++ ) - ; - assert(k); - for(t=0, i=0; (tmp=exparray[i]); i++ ) { - /*log_mpidump("exp: ", tmp );*/ - j = mpi_get_nbits(tmp); - if( j > t ) - t = j; - } - /*log_mpidump("mod: ", m );*/ - assert(i==k); - assert(t); - assert( k < 10 ); - - G = g10_xcalloc( (1<<k) , sizeof *G ); - #ifdef USE_BARRETT - barrett_y = init_barrett( m, &barrett_k, &barrett_r1, &barrett_r2 ); - #endif - /* and calculate */ - tmp = mpi_alloc( mpi_get_nlimbs(m)+1 ); - mpi_set_ui( res, 1 ); - for(i = 1; i <= t; i++ ) { - barrett_mulm(tmp, res, res, m, barrett_y, barrett_k, - barrett_r1, barrett_r2 ); - idx = build_index( exparray, k, i, t ); - assert( idx >= 0 && idx < (1<<k) ); - if( !G[idx] ) { - if( !idx ) - G[0] = mpi_alloc_set_ui( 1 ); - else { - for(j=0; j < k; j++ ) { - if( (idx & (1<<j) ) ) { - if( !G[idx] ) - G[idx] = mpi_copy( basearray[j] ); - else - barrett_mulm( G[idx], G[idx], basearray[j], - m, barrett_y, barrett_k, barrett_r1, barrett_r2 ); - } - } - if( !G[idx] ) - G[idx] = mpi_alloc(0); - } - } - barrett_mulm(res, tmp, G[idx], m, barrett_y, barrett_k, barrett_r1, barrett_r2 ); - } - - /* cleanup */ - mpi_free(tmp); - #ifdef USE_BARRETT - mpi_free(barrett_y); - mpi_free(barrett_r1); - mpi_free(barrett_r2); - #endif - for(i=0; i < (1<<k); i++ ) - mpi_free(G[i]); - g10_free(G); -} - - - -#ifdef USE_BARRETT -static void -barrett_mulm( MPI w, MPI u, MPI v, MPI m, MPI y, int k, MPI r1, MPI r2 ) -{ - mpi_mul(w, u, v); - if( calc_barrett( w, w, m, y, k, r1, r2 ) ) - mpi_fdiv_r( w, w, m ); -} - -/**************** - * Barrett precalculation: y = floor(b^(2k) / m) - */ -static MPI -init_barrett( MPI m, int *k, MPI *r1, MPI *r2 ) -{ - MPI tmp; - - mpi_normalize( m ); - *k = mpi_get_nlimbs( m ); - tmp = mpi_alloc( *k + 1 ); - mpi_set_ui( tmp, 1 ); - mpi_lshift_limbs( tmp, 2 * *k ); - mpi_fdiv_q( tmp, tmp, m ); - *r1 = mpi_alloc( 2* *k + 1 ); - *r2 = mpi_alloc( 2* *k + 1 ); - return tmp; -} - -/**************** - * Barrett reduction: We assume that these conditions are met: - * Given x =(x_2k-1 ...x_0)_b - * m =(m_k-1 ....m_0)_b with m_k-1 != 0 - * Output r = x mod m - * Before using this function init_barret must be used to calucalte y and k. - * Returns: false = no error - * true = can't perform barret reduction - */ -static int -calc_barrett( MPI r, MPI x, MPI m, MPI y, int k, MPI r1, MPI r2 ) -{ - int xx = k > 3 ? k-3:0; - - mpi_normalize( x ); - if( mpi_get_nlimbs(x) > 2*k ) - return 1; /* can't do it */ - - /* 1. q1 = floor( x / b^k-1) - * q2 = q1 * y - * q3 = floor( q2 / b^k+1 ) - * Actually, we don't need qx, we can work direct on r2 - */ - mpi_set( r2, x ); - mpi_rshift_limbs( r2, k-1 ); - mpi_mul( r2, r2, y ); - mpi_rshift_limbs( r2, k+1 ); - - /* 2. r1 = x mod b^k+1 - * r2 = q3 * m mod b^k+1 - * r = r1 - r2 - * 3. if r < 0 then r = r + b^k+1 - */ - mpi_set( r1, x ); - if( r1->nlimbs > k+1 ) /* quick modulo operation */ - r1->nlimbs = k+1; - mpi_mul( r2, r2, m ); - if( r2->nlimbs > k+1 ) /* quick modulo operation */ - r2->nlimbs = k+1; - mpi_sub( r, r1, r2 ); - - if( mpi_is_neg( r ) ) { - MPI tmp; - - tmp = mpi_alloc( k + 2 ); - mpi_set_ui( tmp, 1 ); - mpi_lshift_limbs( tmp, k+1 ); - mpi_add( r, r, tmp ); - mpi_free(tmp); - } - - /* 4. while r >= m do r = r - m */ - while( mpi_cmp( r, m ) >= 0 ) - mpi_sub( r, r, m ); - - return 0; -} -#endif /* USE_BARRETT */ - |