+++ /dev/null
-/*
- * 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"
-
-/*
- * This file contains some additional functions for "i15" big integers.
- * These functions are needed to support ECDSA.
- */
-
-/* see inner.h */
-void
-br_i15_rshift(uint16_t *x, int count)
-{
- size_t u, len;
- unsigned r;
-
- len = (x[0] + 15) >> 4;
- if (len == 0) {
- return;
- }
- r = x[1] >> count;
- for (u = 2; u <= len; u ++) {
- unsigned w;
-
- w = x[u];
- x[u - 1] = ((w << (15 - count)) | r) & 0x7FFF;
- r = w >> count;
- }
- x[len] = r;
-}
-
-/* see inner.h */
-uint32_t
-br_i15_bit_length(uint16_t *x, size_t xlen)
-{
- uint32_t tw, twk;
-
- tw = 0;
- twk = 0;
- while (xlen -- > 0) {
- uint32_t w, c;
-
- c = EQ(tw, 0);
- w = x[xlen];
- tw = MUX(c, w, tw);
- twk = MUX(c, (uint32_t)xlen, twk);
- }
- return (twk << 4) + BIT_LENGTH(tw);
-}
-
-/* see inner.h */
-void
-br_i15_decode(uint16_t *x, const void *src, size_t len)
-{
- const unsigned char *buf;
- size_t v;
- uint32_t acc;
- int acc_len;
-
- buf = src;
- v = 1;
- acc = 0;
- acc_len = 0;
- while (len -- > 0) {
- uint32_t b;
-
- b = buf[len];
- acc |= (b << acc_len);
- acc_len += 8;
- if (acc_len >= 15) {
- x[v ++] = acc & 0x7FFF;
- acc_len -= 15;
- acc >>= 15;
- }
- }
- if (acc_len != 0) {
- x[v ++] = acc;
- }
- x[0] = br_i15_bit_length(x + 1, v - 1);
-}
-
-/* see inner.h */
-void
-br_i15_from_monty(uint16_t *x, const uint16_t *m, uint16_t m0i)
-{
- size_t len, u, v;
-
- len = (m[0] + 15) >> 4;
- for (u = 0; u < len; u ++) {
- uint32_t f, cc;
-
- f = MUL15(x[1], m0i) & 0x7FFF;
- cc = 0;
- for (v = 0; v < len; v ++) {
- uint32_t z;
-
- z = (uint32_t)x[v + 1] + MUL15(f, m[v + 1]) + cc;
- cc = z >> 15;
- if (v != 0) {
- x[v] = z & 0x7FFF;
- }
- }
- x[len] = cc;
- }
-
- /*
- * We may have to do an extra subtraction, but only if the
- * value in x[] is indeed greater than or equal to that of m[],
- * which is why we must do two calls (first call computes the
- * carry, second call performs the subtraction only if the carry
- * is 0).
- */
- br_i15_sub(x, m, NOT(br_i15_sub(x, m, 0)));
-}