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head/contrib/bearssl/src/int/i15_modpow.c
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svn:eol-style | null | native \ No newline at end of property |
svn:keywords | null | FreeBSD=%H \ No newline at end of property |
svn:mime-type | null | text/plain \ No newline at end of property |
/* | |||||
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org> | |||||
* | |||||
* Permission is hereby granted, free of charge, to any person obtaining | |||||
* a copy of this software and associated documentation files (the | |||||
* "Software"), to deal in the Software without restriction, including | |||||
* without limitation the rights to use, copy, modify, merge, publish, | |||||
* distribute, sublicense, and/or sell copies of the Software, and to | |||||
* permit persons to whom the Software is furnished to do so, subject to | |||||
* the following conditions: | |||||
* | |||||
* The above copyright notice and this permission notice shall be | |||||
* included in all copies or substantial portions of the Software. | |||||
* | |||||
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, | |||||
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF | |||||
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND | |||||
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS | |||||
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN | |||||
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN | |||||
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |||||
* SOFTWARE. | |||||
*/ | |||||
#include "inner.h" | |||||
/* see inner.h */ | |||||
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) | |||||
{ | |||||
size_t mlen; | |||||
unsigned k; | |||||
mlen = ((m[0] + 31) >> 4) * sizeof m[0]; | |||||
memcpy(t1, x, mlen); | |||||
br_i15_to_monty(t1, m); | |||||
br_i15_zero(x, m[0]); | |||||
x[1] = 1; | |||||
for (k = 0; k < ((unsigned)elen << 3); k ++) { | |||||
uint32_t ctl; | |||||
ctl = (e[elen - 1 - (k >> 3)] >> (k & 7)) & 1; | |||||
br_i15_montymul(t2, x, t1, m, m0i); | |||||
CCOPY(ctl, x, t2, mlen); | |||||
br_i15_montymul(t2, t1, t1, m, m0i); | |||||
memcpy(t1, t2, mlen); | |||||
} | |||||
} |