mirror of
https://github.com/trezor/trezor-firmware.git
synced 2024-11-15 20:19:23 +00:00
59 lines
1.9 KiB
C
59 lines
1.9 KiB
C
/*
|
|
* This file is part of the Trezor project, https://trezor.io/
|
|
*
|
|
* Copyright (c) SatoshiLabs
|
|
*
|
|
* This program is free software: you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation, either version 3 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include STM32_HAL_H
|
|
|
|
#include "rng.h"
|
|
|
|
#pragma GCC optimize( \
|
|
"no-stack-protector") // applies to all functions in this file
|
|
|
|
void rng_init(void) {
|
|
// enable TRNG peripheral clock
|
|
// use the HAL version due to section 2.1.6 of STM32F42xx Errata sheet
|
|
// "Delay after an RCC peripheral clock enabling"
|
|
__HAL_RCC_RNG_CLK_ENABLE();
|
|
RNG->CR = RNG_CR_RNGEN; // enable TRNG
|
|
}
|
|
|
|
uint32_t rng_read(const uint32_t previous, const uint32_t compare_previous) {
|
|
uint32_t temp = previous;
|
|
do {
|
|
while ((RNG->SR & (RNG_SR_SECS | RNG_SR_CECS | RNG_SR_DRDY)) != RNG_SR_DRDY)
|
|
; // wait until TRNG is ready
|
|
temp = RNG->DR; // read the data from the TRNG
|
|
} while (compare_previous &&
|
|
(temp == previous)); // RM0090 section 24.3.1 FIPS continuous random
|
|
// number generator test
|
|
return temp;
|
|
}
|
|
|
|
uint32_t rng_get(void) {
|
|
// reason for keeping history: RM0090 section 24.3.1 FIPS continuous random
|
|
// number generator test
|
|
static uint32_t previous = 0, current = 0;
|
|
if (previous == current) {
|
|
previous = rng_read(previous, 0);
|
|
} else {
|
|
previous = current;
|
|
}
|
|
current = rng_read(previous, 1);
|
|
return current;
|
|
}
|