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trezor-firmware/rand.c
2015-12-14 22:50:28 +01:00

101 lines
2.4 KiB
C

/**
* Copyright (c) 2013-2014 Tomas Dzetkulic
* Copyright (c) 2013-2014 Pavol Rusnak
*
* 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 <stdio.h>
#ifdef _WIN32
#include <time.h>
#else
#include <assert.h>
#endif
#include "rand.h"
static FILE *frand = NULL;
int finalize_rand(void)
{
#ifdef _WIN32
return 0;
#else
if (!frand) return 0;
int err = fclose(frand);
frand = NULL;
return err;
#endif
}
uint32_t random32(void)
{
#ifdef _WIN32
srand((unsigned)time(NULL));
return ((rand() % 0xFF) | ((rand() % 0xFF) << 8) | ((rand() % 0xFF) << 16) | ((rand() % 0xFF) << 24));
#else
uint32_t r;
size_t len = sizeof(r);
if (!frand) {
frand = fopen("/dev/urandom", "r");
}
size_t len_read = fread(&r, 1, len, frand);
(void)len_read;
assert(len_read == len);
return r;
#endif
}
uint32_t random_uniform(uint32_t n)
{
uint32_t x, max = 0xFFFFFFFF - (0xFFFFFFFF % n);
while ((x = random32()) >= max);
return x / (max / n);
}
void random_buffer(uint8_t *buf, size_t len)
{
#ifdef _WIN32
srand((unsigned)time(NULL));
size_t i;
for (i = 0; i < len; i++) {
buf[i] = rand() % 0xFF;
}
#else
if (!frand) {
frand = fopen("/dev/urandom", "r");
}
size_t len_read = fread(buf, 1, len, frand);
(void)len_read;
assert(len_read == len);
#endif
}
void random_permute(char *str, size_t len)
{
int i, j;
char t;
for (i = len - 1; i >= 1; i--) {
j = random_uniform(i + 1);
t = str[j];
str[j] = str[i];
str[i] = t;
}
}