用c语言编写SHA-1算法

以下是一个用C语言编写的SHA-1算法的示例代码：

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

// 定义常量
#define SHA1_BLOCK_SIZE 20

// 定义函数
void sha1(const uint8_t *message, uint32_t len, uint8_t *hash) {
    uint32_t h[5] = {0x67452301, 0xEFCDAB89, 0x98BADCFE, 0x10325476, 0xC3D2E1F0};
    uint32_t w[80];
    uint32_t a, b, c, d, e, f, k, temp;

    for (int i = 0; i < len / 64; i++) {
        // 将消息分块
        for (int j = 0; j < 16; j++) {
            w[j] = (message[i*64 + j*4] << 24) | (message[i*64 + j*4 + 1] << 16) | (message[i*64 + j*4 + 2] << 8) | (message[i*64 + j*4 + 3]);
        }
        for (int j = 16; j < 80; j++) {
            w[j] = (w[j-3] ^ w[j-8] ^ w[j-14] ^ w[j-16]);
            w[j] = (w[j] << 1) | (w[j] >> 31);
        }

        // 初始化变量
        a = h[0], b = h[1], c = h[2], d = h[3], e = h[4];

        // 消息扩展和算法迭代
        for (int j = 0; j < 80; j++) {
            if (j < 20) {
                f = (b & c) | (~b & d);
                k = 0x5A827999;
            } else if (j < 40) {
                f = b ^ c ^ d;
                k = 0x6ED9EBA1;
            } else if (j < 60) {
                f = (b & c) | (b & d) | (c & d);
                k = 0x8F1BBCDC;
            } else {
                f = b ^ c ^ d;
                k = 0xCA62C1D6;
            }

            temp = (a << 5) | (a >> 27);
            temp += f + e + k + w[j];
            e = d;
            d = c;
            c = (b << 30) | (b >> 2);
            b = a;
            a = temp;
        }

        // 更新哈希值
        h[0] += a;
        h[1] += b;
        h[2] += c;
        h[3] += d;
        h[4] += e;
    }

    // 输出哈希值
    for (int i = 0; i < 5; i++) {
        hash[i*4] = (h[i] >> 24) & 0xFF;
        hash[i*4 + 1] = (h[i] >> 16) & 0xFF;
        hash[i*4 + 2] = (h[i] >> 8) & 0xFF;
        hash[i*4 + 3] = h[i] & 0xFF;
    }
}

int main() {
    uint8_t message[] = "Hello, world!";
    uint8_t hash[SHA1_BLOCK_SIZE];

    sha1(message, strlen(message), hash);

    printf("Message: %s\n", message);
    printf("Hash: ");
    for (int i = 0; i < SHA1_BLOCK_SIZE; i++) {
        printf("%02x", hash[i]);
    }
    printf("\n");

    return 0;
}

该代码将输入的消息分块、进行消息扩展和算法迭代，最终输出20字节的哈希值。需要注意的是，该代码并不是SHA-1算法的最优实现，仅供参考。