1 /* mpz_powm_sec(res,base,exp,mod) -- Set R to (U^E) mod M.
3 Contributed to the GNU project by Torbjorn Granlund.
5 Copyright 1991, 1993, 1994, 1996, 1997, 2000, 2001, 2002, 2005, 2008, 2009
6 Free Software Foundation, Inc.
8 This file is part of the GNU MP Library.
10 The GNU MP Library is free software; you can redistribute it and/or modify
11 it under the terms of the GNU Lesser General Public License as published by
12 the Free Software Foundation; either version 3 of the License, or (at your
13 option) any later version.
15 The GNU MP Library is distributed in the hope that it will be useful, but
16 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
17 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
18 License for more details.
20 You should have received a copy of the GNU Lesser General Public License
21 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
29 mpz_powm_sec (mpz_ptr r, mpz_srcptr b, mpz_srcptr e, mpz_srcptr m)
34 mp_size_t rn, bn, es, en;
47 if (UNLIKELY (es <= 0))
52 /* b^0 mod m, b is anything and m is non-zero.
53 Result is 1 mod m, i.e., 1 or 0 depending on if m = 1. */
54 SIZ(r) = n != 1 || mp[0] != 1;
65 tp = TMP_ALLOC_LIMBS (n + mpn_powm_sec_itch (bn, en, n));
72 mpn_powm_sec (rp, bp, bn, ep, en, mp, n, tp);
76 MPN_NORMALIZE (rp, rn);
78 if ((ep[0] & 1) && SIZ(b) < 0 && rn != 0)
80 mpn_sub (rp, PTR(m), n, rp, rn);
82 MPN_NORMALIZE (rp, rn);
87 MPN_COPY (PTR(r), rp, rn);