hello_sha256.c

/**
 * Copyright (c) 2023 Raspberry Pi (Trading) Ltd.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <stdio.h>
#include <string.h>
// Include sys/types.h before inttypes.h to work around issue with
// certain versions of GCC and newlib which causes omission of PRIu64
#include <sys/types.h>
#include <inttypes.h>
#include <stdlib.h>

#include "pico/stdlib.h"
#include "pico/sha256.h"

// This was generated by cmake from sample.txt.inc
#include "sample.txt.inc"

static void sha_example() {
    printf("Text: %d bytes\n", sizeof(sample_txt) - 1);
    for(int i = 0; i < sizeof(sample_txt) - 1; i++) {
        if (i > 0 && i % 128 == 0) printf("\n");
        putchar(sample_txt[i]);
    }
    printf("\n");

    // Allocate a state object and start the calculation
    pico_sha256_state_t state;
    int rc = pico_sha256_start_blocking(&state, SHA256_BIG_ENDIAN, true); // using some DMA system resources
    hard_assert(rc == PICO_OK);
    pico_sha256_update_blocking(&state, (const uint8_t*)sample_txt, sizeof(sample_txt) - 1);

    // Get the result of the sha256 calculation
    sha256_result_t result;
    pico_sha256_finish(&state, &result);

    // print resulting sha256 result
    printf("Result:\n");
    for(int i = 0; i < SHA256_RESULT_BYTES; i++) {
        printf("%02x ", result.bytes[i]);
        if ((i+1) % 16 == 0) printf("\n");
    }

    // check it's what we expect from "sha256sum sample.txt"
    const uint8_t sha_expected[SHA256_RESULT_BYTES] = {
        0x2d, 0x8c, 0x2f, 0x6d, 0x97, 0x8c, 0xa2, 0x17, 0x12, 0xb5, 0xf6, 0xde, 0x36, 0xc9, 0xd3, 0x1f,
        0xa8, 0xe9, 0x6a, 0x4f, 0xa5, 0xd8, 0xff, 0x8b, 0x01, 0x88, 0xdf, 0xb9, 0xe7, 0xc1, 0x71, 0xbb
    };
    hard_assert(memcmp(sha_expected, &result, SHA256_RESULT_BYTES) == 0);
}


#define BUFFER_SIZE 10000

// A performance test with a large amount of data
static void nist_test(bool use_dma) {
    // nist 3
    uint8_t *buffer = malloc(BUFFER_SIZE);
    memset(buffer, 0x61, BUFFER_SIZE);
    const uint8_t nist_3_expected[] = { \
        0xcd, 0xc7, 0x6e, 0x5c, 0x99, 0x14, 0xfb, 0x92, 0x81, 0xa1, 0xc7, 0xe2, 0x84, 0xd7, 0x3e, 0x67,
        0xf1, 0x80, 0x9a, 0x48, 0xa4, 0x97, 0x20, 0x0e, 0x04, 0x6d, 0x39, 0xcc, 0xc7, 0x11, 0x2c, 0xd0 };

    uint64_t start = time_us_64();
    pico_sha256_state_t state;
    int rc = pico_sha256_start_blocking(&state, SHA256_BIG_ENDIAN, use_dma); // call start once
    hard_assert(rc == PICO_OK);
    for(int i = 0; i < 1000000; i += BUFFER_SIZE) {
        pico_sha256_update_blocking(&state, buffer, BUFFER_SIZE); // call update as many times as required
    }
    sha256_result_t result;
    pico_sha256_finish(&state, &result); // Call finish when done to get the result

    // Display the time taken
    uint64_t pico_time = time_us_64() - start;
    printf("Time for sha256 of 1M bytes %s DMA %"PRIu64"ms\n", use_dma ? "with" : "without", pico_time / 1000);
    hard_assert(memcmp(nist_3_expected, result.bytes, SHA256_RESULT_BYTES) == 0);
}

int main() {
    stdio_init_all();

    sha_example();

    // performance test with and without DMA
    nist_test(false);
    nist_test(true);

    printf("Success\n");
}