Diffstat (limited to 'pwmanager/libcrypt/mpi/mpi-pow.c') (more/less context) (show whitespace changes)
| -rw-r--r-- | pwmanager/libcrypt/mpi/mpi-pow.c | 302 |
1 files changed, 302 insertions, 0 deletions
diff --git a/pwmanager/libcrypt/mpi/mpi-pow.c b/pwmanager/libcrypt/mpi/mpi-pow.c new file mode 100644 index 0000000..61a115f --- a/dev/null +++ b/pwmanager/libcrypt/mpi/mpi-pow.c @@ -0,0 +1,302 @@ +/* mpi-pow.c - MPI functions + * 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, 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. + */ + +#include <config.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include "mpi-internal.h" +#include "longlong.h" +#include <assert.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) +{ + mpi_ptr_t rp, ep, mp, bp; + mpi_size_t esize, msize, bsize, rsize; + int esign, msign, bsign, rsign; + int esec, msec, bsec, rsec; + mpi_size_t size; + int mod_shift_cnt; + int negative_result; + mpi_ptr_t mp_marker=NULL, bp_marker=NULL, ep_marker=NULL; + mpi_ptr_t xp_marker=NULL; + unsigned int mp_nlimbs = 0, bp_nlimbs = 0, ep_nlimbs = 0; + unsigned int xp_nlimbs = 0; + int assign_rp = 0; + mpi_ptr_t tspace = NULL; + mpi_size_t tsize=0; /* to avoid compiler warning */ + /* fixme: we should check that the warning is void*/ + + esize = expo->nlimbs; + msize = mod->nlimbs; + size = 2 * msize; + esign = expo->sign; + 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; + } + + if( res->alloced < size ) { + /* We have to allocate more space for RES. If any of the input + * parameters are identical to RES, defer deallocation of the old + * space. */ + if( rp == ep || rp == mp || rp == bp ) { + rp = mpi_alloc_limb_space( size, rsec ); + assign_rp = 1; + } + else { + mpi_resize( res, size ); + rp = res->d; + } + } + else { /* Make BASE, EXPO and MOD not overlap with RES. */ + if( rp == bp ) { + /* RES and BASE are identical. Allocate temp. space for BASE. */ + 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.*/ + assert( !mp_marker ); + mp_nlimbs = msec?msize:0; + mp = mp_marker = mpi_alloc_limb_space( msize, msec ); + MPN_COPY(mp, rp, msize); + } + } + + MPN_COPY( rp, bp, bsize ); + rsize = bsize; + rsign = bsign; + + { + 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 { + 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 ); + } + + 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); + } + res->nlimbs = rsize; + res->sign = rsign; + + leave: + if( assign_rp ) _gcry_mpi_assign_limb_space( res, rp, size ); + 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 ); +} + |