neorv32/sw/example/demo_trng/main.c

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// #################################################################################################
// # << NEORV32 - TRNG Demo Program >> #
// # ********************************************************************************************* #
// # BSD 3-Clause License #
// # #
// # Copyright (c) 2023, Stephan Nolting. All rights reserved. #
// # #
// # Redistribution and use in source and binary forms, with or without modification, are #
// # permitted provided that the following conditions are met: #
// # #
// # 1. Redistributions of source code must retain the above copyright notice, this list of #
// # conditions and the following disclaimer. #
// # #
// # 2. Redistributions in binary form must reproduce the above copyright notice, this list of #
// # conditions and the following disclaimer in the documentation and/or other materials #
// # provided with the distribution. #
// # #
// # 3. Neither the name of the copyright holder nor the names of its contributors may be used to #
// # endorse or promote products derived from this software without specific prior written #
// # permission. #
// # #
// # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS #
// # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF #
// # MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE #
// # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, #
// # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE #
// # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED #
// # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING #
// # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED #
// # OF THE POSSIBILITY OF SUCH DAMAGE. #
// # ********************************************************************************************* #
// # The NEORV32 Processor - https://github.com/stnolting/neorv32 (c) Stephan Nolting #
// #################################################################################################
/**********************************************************************//**
* @file demo_trng/main.c
* @author Stephan Nolting
* @brief True random number generator demo program.
**************************************************************************/
#include <neorv32.h>
/**********************************************************************//**
* @name User configuration
**************************************************************************/
/**@{*/
/** UART BAUD rate */
#define BAUD_RATE 19200
/**@}*/
// prototypes
void print_random_data(void);
void repetition_count_test(void);
void adaptive_proportion_test(void);
void generate_histogram(void);
void compute_rate(void);
/**********************************************************************//**
* Simple true random number test/demo program.
*
* @note This program requires the UART and the TRNG to be synthesized.
*
* @return 0 if execution was successful
**************************************************************************/
int main(void) {
// check if UART unit is implemented at all
if (neorv32_uart0_available() == 0) {
return 1;
}
// capture all exceptions and give debug info via UART
// this is not required, but keeps us safe
neorv32_rte_setup();
// setup UART at default baud rate, no interrupts
neorv32_uart0_setup(BAUD_RATE, 0);
// intro
neorv32_uart0_printf("\n<<< NEORV32 TRNG Demo >>>\n");
// check if TRNG unit is implemented at all
if (neorv32_trng_available() == 0) {
neorv32_uart0_printf("ERROR: no TRNG implemented!\n");
return 1;
}
// check if TRNG is using simulation mode
if (neorv32_trng_check_sim_mode() != 0) {
neorv32_uart0_printf("WARNING! TRNG uses simulation-only mode implementing a pseudo-RNG (LFSR)\n");
neorv32_uart0_printf(" instead of the physical entropy sources!\n");
}
// enable TRNG
neorv32_uart0_printf("\nTRNG FIFO depth: %i\n", neorv32_trng_get_fifo_depth());
neorv32_uart0_printf("Starting TRNG...\n");
neorv32_trng_enable(0); // no interrupts
neorv32_cpu_delay_ms(100); // TRNG "warm up"
while(1) {
// main menu
neorv32_uart0_printf("\nCommands:\n"
" n: Print 8-bit random numbers (abort by pressing any key)\n"
" h: Generate histogram and analyze data\n"
" t: Compute average random generation rate\n"
" 1: Run repetition count test (NIST SP 800-90B)\n"
" 2: Run adaptive proportion test (NIST SP 800-90B)\n");
neorv32_uart0_printf("CMD:> ");
char cmd = neorv32_uart0_getc();
neorv32_uart0_putc(cmd); // echo
neorv32_uart0_printf("\n");
if (cmd == 'n') {
print_random_data();
}
else if (cmd == 't') {
compute_rate();
}
else if (cmd == 'h') {
generate_histogram();
}
else if (cmd == '1') {
repetition_count_test();
}
else if (cmd == '2') {
adaptive_proportion_test();
}
else {
neorv32_uart0_printf("Invalid command.\n");
}
}
return 0;
}
/**********************************************************************//**
* Print random numbers until a key is pressed.
**************************************************************************/
void print_random_data(void) {
uint32_t num_samples = 0;
uint8_t trng_data;
neorv32_trng_fifo_clear();
while(1) {
if (neorv32_trng_get(&trng_data)) {
continue;
}
neorv32_uart0_printf("%u ", (uint32_t)(trng_data));
num_samples++;
if (neorv32_uart0_char_received()) { // abort when key pressed
neorv32_uart0_char_received_get(); // discard received char
break;
}
}
neorv32_uart0_printf("\nPrinted samples: %u\n", num_samples);
}
/**********************************************************************//**
* Run repetition count test (NIST SP 800-90B)
**************************************************************************/
void repetition_count_test(void) {
int fail = 0;
uint8_t a, x;
int b = 0;
const int c = 10; // cutoff value
neorv32_uart0_printf("\nRunning test... Press any key to stop.\n");
neorv32_uart0_printf("Cut-off value = %u\n", c);
neorv32_trng_fifo_clear();
while (neorv32_trng_get(&a));
b = 1;
while (1) {
while (neorv32_trng_get(&x));
if (x == a) {
b++;
if (b >= c) {
fail = 1;
}
}
else {
a = x;
b = 1;
}
if (fail) {
break;
}
if (neorv32_uart0_char_received()) { // abort when key pressed
neorv32_uart0_char_received_get(); // discard received char
break;
}
}
if (fail) {
neorv32_uart0_printf("Test failed!\n");
}
else {
neorv32_uart0_printf("Test ok!\n");
}
}
/**********************************************************************//**
* Run adaptive proportion test (NIST SP 800-90B)
**************************************************************************/
void adaptive_proportion_test(void) {
int fail = 0;
uint8_t a,x;
int b = 0;
const int c = 13; // cutoff value
const int w = 512; // window size
int i;
neorv32_uart0_printf("\nRunning test... Press any key to stop.\n");
neorv32_uart0_printf("Cut-off value = %u, windows size = %u\n", c, w);
neorv32_trng_fifo_clear();
while (1) {
while (neorv32_trng_get(&a));
b = 1;
for (i=1; i<w; i++) {
while(neorv32_trng_get(&x));
if (a == x) {
b++;
}
if (b >= c) {
fail = 1;
}
}
if (fail) {
break;
}
if (neorv32_uart0_char_received()) { // abort when key pressed
neorv32_uart0_char_received_get(); // discard received char
break;
}
}
if (fail) {
neorv32_uart0_printf("Test failed!\n");
}
else {
neorv32_uart0_printf("Test ok!\n");
}
}
/**********************************************************************//**
* Generate and print histogram. Samples random data until a key is pressed.
**************************************************************************/
void generate_histogram(void) {
const uint32_t n_samples = 4*1024*1024;
uint32_t hist[256];
uint32_t i, cnt;
uint8_t trng_data;
uint64_t average = 0;
neorv32_trng_fifo_clear();
neorv32_uart0_printf("Sampling... Press any key to stop.\n");
// clear histogram
for (i=0; i<256; i++) {
hist[i] = 0;
}
neorv32_trng_fifo_clear();
// sample random data
cnt = 0;
while (1) {
// get raw TRNG data
if (neorv32_trng_get(&trng_data)) {
continue;
}
// add to histogram
hist[trng_data & 0xff]++;
cnt++;
// average
average += (uint64_t)trng_data;
// max number of samples
if (cnt >= n_samples) {
break;
}
// user abort
if (neorv32_uart0_char_received()) {
neorv32_uart0_char_received_get(); // discard received char
break;
}
}
average = average / cnt;
// analyze histogram data
uint32_t occ_avg = cnt / 256;
int32_t occ_avg_dev_tmp = 0;
uint32_t occ_avg_dev = 0;
uint32_t occ_tmp;
uint32_t occ_max = 0;
uint32_t bin_max = 0;
uint32_t occ_min = -1;
uint32_t bin_min = 0;
for (i=0; i<256; i++) {
occ_tmp = (int32_t)hist[i];
occ_avg_dev_tmp = (int32_t)occ_avg - (int32_t)occ_tmp;
if (occ_avg_dev_tmp < 0) {
occ_avg_dev_tmp = -occ_avg_dev_tmp;
}
occ_avg_dev += occ_avg_dev_tmp;
if (occ_tmp < occ_min) {
occ_min = occ_tmp;
bin_min = i;
}
if (occ_tmp > occ_max) {
occ_max = occ_tmp;
bin_max = i;
}
}
occ_avg_dev = occ_avg_dev / 256;
// print histogram
neorv32_uart0_printf("Histogram [random data value] : [# occurrences]\n");
for (i=0; i<256; i++) {
neorv32_uart0_printf("%u: %u\n", (uint32_t)i, hist[i]);
}
neorv32_uart0_printf("\n");
// print results
neorv32_uart0_printf("[NOTE] integer numbers only\n");
neorv32_uart0_printf("Number of samples: %u\n", cnt);
neorv32_uart0_printf("Arithmetic mean: %u (optimum would be 127)\n", (uint32_t)average);
neorv32_uart0_printf("\nHistogram occurrence\n");
neorv32_uart0_printf("Average: %u (optimum would be %u/256 = %u)\n", occ_avg, n_samples, n_samples/256);
neorv32_uart0_printf("Min: %u = average - %u (deviation) at bin %u (optimum deviation would be 0)\n", occ_min, occ_avg - occ_min, bin_min);
neorv32_uart0_printf("Max: %u = average + %u (deviation) at bin %u (optimum deviation would be 0)\n", occ_max, occ_max - occ_avg, bin_max);
neorv32_uart0_printf("Average dev.: +/- %u (optimum would be 0)\n", occ_avg_dev);
}
/**********************************************************************//**
* Compute average random generation rate
**************************************************************************/
void compute_rate(void) {
const uint32_t n_samples = 16*1024;
uint32_t i;
uint32_t tmp;
uint32_t cycles = neorv32_cpu_csr_read(CSR_CYCLE);
i = 0;
while (i<n_samples) {
tmp = NEORV32_TRNG->CTRL;
if (tmp & (1<<TRNG_CTRL_VALID)) { // valid sample?
i++;
}
}
uint32_t delta = neorv32_cpu_csr_read(CSR_CYCLE) - cycles;
uint32_t cycles_per_rnd = delta / n_samples;
uint32_t rnd_per_sec = NEORV32_SYSINFO->CLK / cycles_per_rnd;
neorv32_uart0_printf("\nAverage random generation rate\n");
neorv32_uart0_printf("Cycles per random byte: ~%u\n", cycles_per_rnd);
neorv32_uart0_printf("Throughput (bytes/s): ~%u\n", rnd_per_sec);
}