c语言sha256算法代码

以下是一个简单的C语言实现SHA-256算法的代码：

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

#define ROTR(x, n) (((x) >> (n)) | ((x) << (32 - (n))))
#define SHR(x, n) ((x) >> (n))
#define Sigma0(x) (ROTR(x, 2) ^ ROTR(x, 13) ^ ROTR(x, 22))
#define Sigma1(x) (ROTR(x, 6) ^ ROTR(x, 11) ^ ROTR(x, 25))
#define sigma0(x) (ROTR(x, 7) ^ ROTR(x, 18) ^ SHR(x, 3))
#define sigma1(x) (ROTR(x, 17) ^ ROTR(x, 19) ^ SHR(x, 10))

const uint32_t K[] = {
    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
};

void sha256(const uint8_t *data, uint32_t len, uint8_t *digest)
{
    uint32_t H[] = {
        0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
        0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19
    };

    uint32_t W[64];
    uint32_t a, b, c, d, e, f, g, h;
    uint32_t T1, T2;

    uint32_t i, j;

    uint32_t padded_len = ((len + 8 + 63) / 64) * 64;
    uint8_t *padded_data = (uint8_t *)malloc(padded_len);
    memcpy(padded_data, data, len);
    padded_data[len] = 0x80;
    for (i = len + 1; i < padded_len - 8; i++) {
        padded_data[i] = 0x00;
    }
    padded_data[padded_len - 8] = (len >> 24) & 0xff;
    padded_data[padded_len - 7] = (len >> 16) & 0xff;
    padded_data[padded_len - 6] = (len >> 8) & 0xff;
    padded_data[padded_len - 5] = (len >> 0) & 0xff;
    padded_data[padded_len - 4] = 0x00;
    padded_data[padded_len - 3] = 0x00;
    padded_data[padded_len - 2] = 0x00;
    padded_data[padded_len - 1] = 0x00;

    for (i = 0; i < padded_len / 64; i++) {
        for (j = 0; j < 16; j++) {
            W[j] = ((uint32_t)padded_data[i * 64 + j * 4 + 0] << 24) |
                   ((uint32_t)padded_data[i * 64 + j * 4 + 1] << 16) |
                   ((uint32_t)padded_data[i * 64 + j * 4 + 2] << 8) |
                   ((uint32_t)padded_data[i * 64 + j * 4 + 3] << 0);
        }

        for (j = 16; j < 64; j++) {
            W[j] = sigma1(W[j - 2]) + W[j - 7] + sigma0(W[j - 15]) + W[j - 16];
        }

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

        for (j = 0; j < 64; j++) {
            T1 = h + Sigma1(e) + Ch(e, f, g) + K[j] + W[j];
            T2 = Sigma0(a) + Maj(a, b, c);
            h = g;
            g = f;
            f = e;
            e = d + T1;
            d = c;
            c = b;
            b = a;
            a = T1 + T2;
        }

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

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

    free(padded_data);
}

int main()
{
    uint8_t data[] = "hello world";
    uint8_t digest[32];

    sha256(data, sizeof(data) - 1, digest);

    printf("SHA-256 digest: ");
    for (int i = 0; i < 32; i++) {
        printf("%02x", digest[i]);
    }
    printf("\n");

    return 0;
}

这个代码实现了SHA-256算法的核心部分，可用于计算任意长度的数据的哈希值。需要注意的是，这个代码只是一个简单的示例，还有很多细节需要考虑，如填充、字节序等问题。实际使用中，建议使用现成的SHA-256库。