mirror of
https://github.com/trezor/trezor-firmware.git
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65 lines
1.6 KiB
C
65 lines
1.6 KiB
C
/*
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* This file is part of the TREZOR project.
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*
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* Copyright (C) 2014 Pavol Rusnak <stick@satoshilabs.com>
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*
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* This library is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <libopencm3/cm3/common.h>
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#include <libopencm3/stm32/memorymap.h>
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#include <libopencm3/stm32/f2/rng.h>
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#include "rng.h"
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uint32_t random32(void)
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{
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static uint32_t last = 0, new = 0;
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while (new == last) {
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if ((RNG_SR & (RNG_SR_SECS | RNG_SR_CECS | RNG_SR_DRDY)) == RNG_SR_DRDY) {
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new = RNG_DR;
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}
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}
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last = new;
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return new;
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}
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uint32_t random_uniform(uint32_t n)
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{
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uint32_t x, max = 0xFFFFFFFF - (0xFFFFFFFF % n);
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while ((x = random32()) >= max);
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return x / (max / n);
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}
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void random_buffer(uint8_t *buf, size_t len)
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{
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uint32_t r = 0;
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for (size_t i = 0; i < len; i++) {
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if (i % 4 == 0) {
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r = random32();
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}
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buf[i] = (r >> ((i % 4) * 8)) & 0xFF;
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}
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}
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void random_permute(char *str, size_t len)
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{
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for (int i = len - 1; i >= 1; i--) {
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int j = random_uniform(i + 1);
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char t = str[j];
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str[j] = str[i];
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str[i] = t;
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}
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}
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