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82e12d1ec5bb70add4be75e6e7d5d0fbc40098c2
CSPRNG/Core/Src/main.c
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gbucchino 82e12d1ec5 First commit
2026-06-15 20:00:29 +02:00

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/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Main program body
******************************************************************************
* @attention
*
* Copyright (c) 2026 STMicroelectronics.
* All rights reserved.
*
* This software is licensed under terms that can be found in the LICENSE file
* in the root directory of this software component.
* If no LICENSE file comes with this software, it is provided AS-IS.
*
******************************************************************************
*/
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "string.h"
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include"csprng.h"
#include <stdlib.h>
struct entropy_pool s_entropy;
/* USER CODE END Includes */
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
/* USER CODE END PTD */
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
/* USER CODE END PM */
/* Private variables ---------------------------------------------------------*/
ETH_TxPacketConfig TxConfig;
ETH_DMADescTypeDef DMARxDscrTab[ETH_RX_DESC_CNT]; /* Ethernet Rx DMA Descriptors */
ETH_DMADescTypeDef DMATxDscrTab[ETH_TX_DESC_CNT]; /* Ethernet Tx DMA Descriptors */
ETH_HandleTypeDef heth;
RNG_HandleTypeDef hrng;
UART_HandleTypeDef huart3;
PCD_HandleTypeDef hpcd_USB_OTG_FS;
/* USER CODE BEGIN PV */
/* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_ETH_Init(void);
static void MX_USART3_UART_Init(void);
static void MX_USB_OTG_FS_PCD_Init(void);
static void MX_RNG_Init(void);
/* USER CODE BEGIN PFP */
/* USER CODE END PFP */
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
/*
* Fill the entropy structure with random data
*/
void init_entropy(){
// Generate entropy
memset(&s_entropy, 0, sizeof(s_entropy));
while(s_entropy.pool_size < BUFSIZE){
generateEntropy(s_entropy.position++);
s_entropy.pool_size++;
// Add a delay for avoiding the same value
//delay(50);
}
/* We start at 0, ready for pickup to the pool */
s_entropy.position = 0;
}
/*
* Generate a random value from the analog input
* Store the value in the entropy structure at the position specified in argument
*/
static void generateEntropy(int position){
unsigned int sensorValue = 0;
//RNG->CR|=RNG_CR_RNGEN;
RNG->CR = RNG_CR_RNGEN; /* RNG_CR_RNGEN -> 4 */
while (sensorValue == 0){
HAL_GPIO_TogglePin (GPIOB, GPIO_PIN_0);
HAL_Delay (100); /* Insert delay 100 ms */
// Wait until the data is ready
while (RNG_SR_DRDY == 0);
uint32_t random = RNG->DR;
sensorValue = abs(random);
if (sensorValue != 0){
if(sensorValue <= 10)
sensorValue = sensorValue << 5;
else if(sensorValue > 10 && sensorValue <= 100)
sensorValue = sensorValue << 4;
s_entropy.buf[position] = sensorValue;
}
}
}
/*
* Pick a random data from the entropy pool
* This function is the API function to get the random number from the pool
*/
unsigned int prng(){
unsigned int p = 0;
if (s_entropy.position == BUFSIZE)
s_entropy.position = 0;
// We consume the entropy
p = s_entropy.buf[s_entropy.position];
s_entropy.pool_size--;
// We have consumed the entropy, we replace the value by a new one
generateEntropy(s_entropy.position);
s_entropy.position++;
return p;
}
/*
* For the Blum-Blum-Shub, we need to find a prime number and must be congruent 3 modulo 4
*/
static void prime_number_finder(unsigned int *p){
while(!isPrimeNumber(*p) || (*p % 4 != 3))
*p += 1;
}
/*
* Check if the number specified is a prime number
*/
static int isPrimeNumber(unsigned int x){
for (int i = 0; i < SIEVES_LEN; i++){
if (x % sieves[i] == 0)
return 0;
}
return 1;
}
/*
* This function find the GCD
*/
static int gcd(unsigned long a, unsigned long b){
if (b == 0)
return a;
return gcd(b, a % b);
}
unsigned int random_range(int min, int max){
// Wait until the data is ready
while (RNG_SR_DRDY == 0);
uint32_t random = RNG->DR;
return (random % max) + 1;
}
static unsigned short csum(unsigned short *buf, int nwords) {
unsigned long sum = 0;
while (nwords > 0) {
sum += *buf++;
nwords--;
}
sum = (sum >> 16) + (sum & 0xFFFF);
sum += (sum >> 16);
return (unsigned short)(~sum);
}
/*
* This function implement the Blum-Blum-Shub algorithm
* Based on the algorithm described in the Chapter 5:
* https://cacr.uwaterloo.ca/hac/about/chap5.pdf
*/
static unsigned long long bbs(unsigned int *p, unsigned int *q, unsigned long long *s){
/* We pickup data from the entropy pool */
unsigned int p1 = prng();
unsigned int p2 = prng();
unsigned long long n = 0, seed = 0;
// We check if they are prime numbers
prime_number_finder(&p1);
prime_number_finder(&p2);
*p = p1;
*q = p2;
n = (unsigned long long)p1 * (unsigned long long)p2;
/*
* We need to find the seed
* between 1 < s < n - 1 and gcd(s, n) = 1
*/
seed = random_range(1, n);
while (gcd(seed, n) != 1)
seed += 1;
*s = seed;
unsigned long long x0 = (seed * seed) % n;
unsigned long long tmp = x0;
char output[ITER_BBS];
memset(output, 0, ITER_BBS);
int pos = 0;
for (size_t i = 1; i < ITER_BBS; i++){
unsigned long long x = (tmp * tmp) % n;
output[pos++] = (x & 1) + '0';
tmp = x;
}
/* We convert the bit sequence to unsigned long long */
unsigned long long res = 0;
for (int i = 0; i < strlen(output); i++)
res = (res << 1) + output[i] - '0';
return res;
}
/* USER CODE END 0 */
/**
* @brief The application entry point.
* @retval int
*/
int main(void)
{
/* USER CODE BEGIN 1 */
/* USER CODE END 1 */
/* MCU Configuration--------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_ETH_Init();
MX_USART3_UART_Init();
MX_USB_OTG_FS_PCD_Init();
MX_RNG_Init();
/* USER CODE BEGIN 2 */
init_entropy();
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
uint8_t buffer[sizeof(struct prng)];
uint8_t buf_recv;
while (1)
{
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
HAL_StatusTypeDef status = HAL_UART_Receive(&huart3, &buf_recv, 1, 100);
if (status == HAL_OK){
if (buf_recv == 1){
struct prng s_prng = {0};
memset(buffer, 0, sizeof(struct prng));
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_0, GPIO_PIN_SET);
unsigned long long random = bbs(&s_prng.p, &s_prng.q, &s_prng.seed);
s_prng.output = random;
memcpy(buffer, &s_prng, sizeof(struct prng));
HAL_StatusTypeDef s = HAL_UART_Transmit(&huart3, buffer, sizeof(struct prng), 0xF);
// We have finished, we disable the pin
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_0, GPIO_PIN_RESET);
}
}
}
/* USER CODE END 3 */
}
/**
* @brief System Clock Configuration
* @retval None
*/
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
/** Configure the main internal regulator output voltage
*/
__HAL_RCC_PWR_CLK_ENABLE();
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_BYPASS;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 4;
RCC_OscInitStruct.PLL.PLLN = 168;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = 7;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Initializes the CPU, AHB and APB buses clocks
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
{
Error_Handler();
}
}
/**
* @brief ETH Initialization Function
* @param None
* @retval None
*/
static void MX_ETH_Init(void)
{
/* USER CODE BEGIN ETH_Init 0 */
/* USER CODE END ETH_Init 0 */
static uint8_t MACAddr[6];
/* USER CODE BEGIN ETH_Init 1 */
/* USER CODE END ETH_Init 1 */
heth.Instance = ETH;
MACAddr[0] = 0x00;
MACAddr[1] = 0x80;
MACAddr[2] = 0xE1;
MACAddr[3] = 0x00;
MACAddr[4] = 0x00;
MACAddr[5] = 0x00;
heth.Init.MACAddr = &MACAddr[0];
heth.Init.MediaInterface = HAL_ETH_RMII_MODE;
heth.Init.TxDesc = DMATxDscrTab;
heth.Init.RxDesc = DMARxDscrTab;
heth.Init.RxBuffLen = 1524;
/* USER CODE BEGIN MACADDRESS */
/* USER CODE END MACADDRESS */
if (HAL_ETH_Init(&heth) != HAL_OK)
{
Error_Handler();
}
memset(&TxConfig, 0 , sizeof(ETH_TxPacketConfig));
TxConfig.Attributes = ETH_TX_PACKETS_FEATURES_CSUM | ETH_TX_PACKETS_FEATURES_CRCPAD;
TxConfig.ChecksumCtrl = ETH_CHECKSUM_IPHDR_PAYLOAD_INSERT_PHDR_CALC;
TxConfig.CRCPadCtrl = ETH_CRC_PAD_INSERT;
/* USER CODE BEGIN ETH_Init 2 */
/* USER CODE END ETH_Init 2 */
}
/**
* @brief RNG Initialization Function
* @param None
* @retval None
*/
static void MX_RNG_Init(void)
{
/* USER CODE BEGIN RNG_Init 0 */
/* USER CODE END RNG_Init 0 */
/* USER CODE BEGIN RNG_Init 1 */
/* USER CODE END RNG_Init 1 */
hrng.Instance = RNG;
if (HAL_RNG_Init(&hrng) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN RNG_Init 2 */
/* USER CODE END RNG_Init 2 */
}
/**
* @brief USART3 Initialization Function
* @param None
* @retval None
*/
static void MX_USART3_UART_Init(void)
{
/* USER CODE BEGIN USART3_Init 0 */
/* USER CODE END USART3_Init 0 */
/* USER CODE BEGIN USART3_Init 1 */
/* USER CODE END USART3_Init 1 */
huart3.Instance = USART3;
huart3.Init.BaudRate = 115200;
huart3.Init.WordLength = UART_WORDLENGTH_8B;
huart3.Init.StopBits = UART_STOPBITS_1;
huart3.Init.Parity = UART_PARITY_NONE;
huart3.Init.Mode = UART_MODE_TX_RX;
huart3.Init.HwFlowCtl = UART_HWCONTROL_NONE;
huart3.Init.OverSampling = UART_OVERSAMPLING_16;
if (HAL_UART_Init(&huart3) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN USART3_Init 2 */
/* USER CODE END USART3_Init 2 */
}
/**
* @brief USB_OTG_FS Initialization Function
* @param None
* @retval None
*/
static void MX_USB_OTG_FS_PCD_Init(void)
{
/* USER CODE BEGIN USB_OTG_FS_Init 0 */
/* USER CODE END USB_OTG_FS_Init 0 */
/* USER CODE BEGIN USB_OTG_FS_Init 1 */
/* USER CODE END USB_OTG_FS_Init 1 */
hpcd_USB_OTG_FS.Instance = USB_OTG_FS;
hpcd_USB_OTG_FS.Init.dev_endpoints = 4;
hpcd_USB_OTG_FS.Init.speed = PCD_SPEED_FULL;
hpcd_USB_OTG_FS.Init.dma_enable = DISABLE;
hpcd_USB_OTG_FS.Init.phy_itface = PCD_PHY_EMBEDDED;
hpcd_USB_OTG_FS.Init.Sof_enable = ENABLE;
hpcd_USB_OTG_FS.Init.low_power_enable = DISABLE;
hpcd_USB_OTG_FS.Init.lpm_enable = DISABLE;
hpcd_USB_OTG_FS.Init.vbus_sensing_enable = ENABLE;
hpcd_USB_OTG_FS.Init.use_dedicated_ep1 = DISABLE;
if (HAL_PCD_Init(&hpcd_USB_OTG_FS) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN USB_OTG_FS_Init 2 */
/* USER CODE END USB_OTG_FS_Init 2 */
}
/**
* @brief GPIO Initialization Function
* @param None
* @retval None
*/
static void MX_GPIO_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOC_CLK_ENABLE();
__HAL_RCC_GPIOH_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
__HAL_RCC_GPIOB_CLK_ENABLE();
__HAL_RCC_GPIOD_CLK_ENABLE();
__HAL_RCC_GPIOG_CLK_ENABLE();
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(GPIOB, LD1_Pin|LD3_Pin|LD2_Pin, GPIO_PIN_RESET);
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(USB_PowerSwitchOn_GPIO_Port, USB_PowerSwitchOn_Pin, GPIO_PIN_RESET);
/*Configure GPIO pin : USER_Btn_Pin */
GPIO_InitStruct.Pin = USER_Btn_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_IT_RISING;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(USER_Btn_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pins : LD1_Pin LD3_Pin LD2_Pin */
GPIO_InitStruct.Pin = LD1_Pin|LD3_Pin|LD2_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
/*Configure GPIO pin : USB_PowerSwitchOn_Pin */
GPIO_InitStruct.Pin = USB_PowerSwitchOn_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(USB_PowerSwitchOn_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : USB_OverCurrent_Pin */
GPIO_InitStruct.Pin = USB_OverCurrent_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(USB_OverCurrent_GPIO_Port, &GPIO_InitStruct);
/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}
/* USER CODE BEGIN 4 */
void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart)
{
if (huart->Instance == USART3)
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_0, GPIO_PIN_RESET);
}
/* USER CODE END 4 */
/**
* @brief This function is executed in case of error occurrence.
* @retval None
*/
void Error_Handler(void)
{
/* USER CODE BEGIN Error_Handler_Debug */
/* User can add his own implementation to report the HAL error return state */
__disable_irq();
while (1)
{
}
/* USER CODE END Error_Handler_Debug */
}
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t *file, uint32_t line)
{
/* USER CODE BEGIN 6 */
/* User can add his own implementation to report the file name and line number,
ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
/* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
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