1*0957b409SSimon J. Gerraty /*
2*0957b409SSimon J. Gerraty * Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
3*0957b409SSimon J. Gerraty *
4*0957b409SSimon J. Gerraty * Permission is hereby granted, free of charge, to any person obtaining
5*0957b409SSimon J. Gerraty * a copy of this software and associated documentation files (the
6*0957b409SSimon J. Gerraty * "Software"), to deal in the Software without restriction, including
7*0957b409SSimon J. Gerraty * without limitation the rights to use, copy, modify, merge, publish,
8*0957b409SSimon J. Gerraty * distribute, sublicense, and/or sell copies of the Software, and to
9*0957b409SSimon J. Gerraty * permit persons to whom the Software is furnished to do so, subject to
10*0957b409SSimon J. Gerraty * the following conditions:
11*0957b409SSimon J. Gerraty *
12*0957b409SSimon J. Gerraty * The above copyright notice and this permission notice shall be
13*0957b409SSimon J. Gerraty * included in all copies or substantial portions of the Software.
14*0957b409SSimon J. Gerraty *
15*0957b409SSimon J. Gerraty * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16*0957b409SSimon J. Gerraty * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17*0957b409SSimon J. Gerraty * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18*0957b409SSimon J. Gerraty * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19*0957b409SSimon J. Gerraty * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20*0957b409SSimon J. Gerraty * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21*0957b409SSimon J. Gerraty * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22*0957b409SSimon J. Gerraty * SOFTWARE.
23*0957b409SSimon J. Gerraty */
24*0957b409SSimon J. Gerraty
25*0957b409SSimon J. Gerraty #include "inner.h"
26*0957b409SSimon J. Gerraty
27*0957b409SSimon J. Gerraty /* see inner.h */
28*0957b409SSimon J. Gerraty void
br_i15_modpow(uint16_t * x,const unsigned char * e,size_t elen,const uint16_t * m,uint16_t m0i,uint16_t * t1,uint16_t * t2)29*0957b409SSimon J. Gerraty br_i15_modpow(uint16_t *x,
30*0957b409SSimon J. Gerraty const unsigned char *e, size_t elen,
31*0957b409SSimon J. Gerraty const uint16_t *m, uint16_t m0i, uint16_t *t1, uint16_t *t2)
32*0957b409SSimon J. Gerraty {
33*0957b409SSimon J. Gerraty size_t mlen;
34*0957b409SSimon J. Gerraty unsigned k;
35*0957b409SSimon J. Gerraty
36*0957b409SSimon J. Gerraty mlen = ((m[0] + 31) >> 4) * sizeof m[0];
37*0957b409SSimon J. Gerraty memcpy(t1, x, mlen);
38*0957b409SSimon J. Gerraty br_i15_to_monty(t1, m);
39*0957b409SSimon J. Gerraty br_i15_zero(x, m[0]);
40*0957b409SSimon J. Gerraty x[1] = 1;
41*0957b409SSimon J. Gerraty for (k = 0; k < ((unsigned)elen << 3); k ++) {
42*0957b409SSimon J. Gerraty uint32_t ctl;
43*0957b409SSimon J. Gerraty
44*0957b409SSimon J. Gerraty ctl = (e[elen - 1 - (k >> 3)] >> (k & 7)) & 1;
45*0957b409SSimon J. Gerraty br_i15_montymul(t2, x, t1, m, m0i);
46*0957b409SSimon J. Gerraty CCOPY(ctl, x, t2, mlen);
47*0957b409SSimon J. Gerraty br_i15_montymul(t2, t1, t1, m, m0i);
48*0957b409SSimon J. Gerraty memcpy(t1, t2, mlen);
49*0957b409SSimon J. Gerraty }
50*0957b409SSimon J. Gerraty }
51