用c语言实现基于BS模式的SHA-256算法文件完整性程序

以下是基于BS模式的SHA-256算法文件完整性程序的C语言实现：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>

#define ROTL(x, n) (((x) << (n)) | ((x) >> (32 - (n))))
#define ROTR(x, n) (((x) >> (n)) | ((x) << (32 - (n))))
#define SHR(x, n) ((x) >> (n))

#define CH(x, y, z) (((x) & (y)) ^ (~(x) & (z)))
#define MAJ(x, y, z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
#define EP0(x) (ROTR(x, 2) ^ ROTR(x, 13) ^ ROTR(x, 22))
#define EP1(x) (ROTR(x, 6) ^ ROTR(x, 11) ^ ROTR(x, 25))
#define SIG0(x) (ROTR(x, 7) ^ ROTR(x, 18) ^ SHR(x, 3))
#define SIG1(x) (ROTR(x, 17) ^ ROTR(x, 19) ^ SHR(x, 10))

static const uint32_t K[64] = {
    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
    0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
    0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
    0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
    0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
    0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
    0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
    0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
    0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
    0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
    0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
    0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
    0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
    0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
    0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
    0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
};

static void sha256_transform(uint32_t state[8], const uint8_t data[64])
{
    uint32_t a, b, c, d, e, f, g, h, i, j, t1, t2, m[64];

    for (i=0, j=0; i<16; ++i, j+=4)
        m[i] = (data[j] << 24) | (data[j+1] << 16) | (data[j+2] << 8) | (data[j+3]);
    for (; i<64; ++i)
        m[i] = SIG1(m[i-2]) + m[i-7] + SIG0(m[i-15]) + m[i-16];

    a = state[0];
    b = state[1];
    c = state[2];
    d = state[3];
    e = state[4];
    f = state[5];
    g = state[6];
    h = state[7];

    for (i=0; i<64; ++i) {
        t1 = h + EP1(e) + CH(e, f, g) + K[i] + m[i];
        t2 = EP0(a) + MAJ(a, b, c);
        h = g;
        g = f;
        f = e;
        e = d + t1;
        d = c;
        c = b;
        b = a;
        a = t1 + t2;
    }

    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
    state[4] += e;
    state[5] += f;
    state[6] += g;
    state[7] += h;
}

void sha256(const uint8_t *msg, size_t len, uint8_t hash[32])
{
    uint32_t state[8] = {
        0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
        0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19
    };
    uint8_t data[64];
    size_t i, j;

    for (i=0; i<len; ++i) {
        if ((i & 63) == 0 && i > 0)
            sha256_transform(state, data);
        j = i & 63;
        data[j] = msg[i];
    }

    j = i & 63;
    data[j++] = 0x80;
    if (j > 56) {
        memset(data+j, 0, 64-j);
        sha256_transform(state, data);
        j = 0;
    }
    memset(data+j, 0, 56-j);
    uint64_t bitlen = (uint64_t)len * 8;
    data[56] = (bitlen >> 56) & 0xff;
    data[57] = (bitlen >> 48) & 0xff;
    data[58] = (bitlen >> 40) & 0xff;
    data[59] = (bitlen >> 32) & 0xff;
    data[60] = (bitlen >> 24) & 0xff;
    data[61] = (bitlen >> 16) & 0xff;
    data[62] = (bitlen >> 8) & 0xff;
    data[63] = bitlen & 0xff;
    sha256_transform(state, data);

    for (i=0; i<8; ++i) {
        hash[i*4] = (state[i] >> 24) & 0xff;
        hash[i*4+1] = (state[i] >> 16) & 0xff;
        hash[i*4+2] = (state[i] >> 8) & 0xff;
        hash[i*4+3] = state[i] & 0xff;
    }
}

int main(int argc, char **argv)
{
    if (argc < 2) {
        printf("Usage: %s <filename>\n", argv[0]);
        return 1;
    }

    FILE *fp = fopen(argv[1], "rb");
    if (!fp) {
        printf("Unable to open file: %s\n", argv[1]);
        return 1;
    }

    fseek(fp, 0L, SEEK_END);
    size_t size = ftell(fp);
    rewind(fp);

    uint8_t *buf = (uint8_t*)malloc(size);
    if (!buf) {
        printf("Unable to allocate memory\n");
        fclose(fp);
        return 1;
    }

    if (fread(buf, 1, size, fp) != size) {
        printf("Unable to read file: %s\n", argv[1]);
        fclose(fp);
        free(buf);
        return 1;
    }

    uint8_t hash[32];
    sha256(buf, size, hash);

    printf("SHA-256 hash of %s:\n", argv[1]);
    for (int i=0; i<32; ++i)
        printf("%02x", hash[i]);
    printf("\n");

    free(buf);
    fclose(fp);
    return 0;
}

该程序使用了BS模式，对文件进行SHA-256算法计算，并输出计算结果。用户可以在命令行中指定要计算哈希值的文件，程序会打开文件并读取其中的内容，然后对内容进行哈希计算。计算结果以16进制形式输出。