实现SHA-1算法加密的C语言代码

以下是一个简单的实现SHA-1算法加密的C语言代码：

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

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

void sha1(uint8_t* message, uint32_t message_len, uint8_t* digest) {
    uint32_t H[5] = {
        0x67452301,
        0xEFCDAB89,
        0x98BADCFE,
        0x10325476,
        0xC3D2E1F0
    };
    uint32_t K[4] = {
        0x5A827999,
        0x6ED9EBA1,
        0x8F1BBCDC,
        0xCA62C1D6
    };
    uint32_t W[80];
    uint32_t A, B, C, D, E, temp;
    uint32_t i, j;

    // padding message
    uint64_t bit_len = message_len * 8;
    uint32_t pad_len = (bit_len % 512 < 448) ? 512 - bit_len % 512 : 1024 - bit_len % 512;
    uint32_t block_len = (bit_len + pad_len + 64) / 32;
    uint32_t* block = (uint32_t*) malloc(block_len * sizeof(uint32_t));
    memcpy(block, message, message_len);
    block[message_len / 4] |= 0x80 << (24 - message_len % 4 * 8);
    for (i = message_len / 4 + 1; i < block_len - 2; i++) {
        block[i] = 0;
    }
    block[block_len - 2] = bit_len >> 32;
    block[block_len - 1] = bit_len & 0xFFFFFFFF;

    // update hash
    for (i = 0; i < block_len; i += 16) {
        for (j = 0; j < 16; j++) {
            W[j] = block[i + j];
        }
        for (j = 16; j < 80; j++) {
            W[j] = ROTL(W[j - 3] ^ W[j - 8] ^ W[j - 14] ^ W[j - 16], 1);
        }

        A = H[0];
        B = H[1];
        C = H[2];
        D = H[3];
        E = H[4];

        for (j = 0; j < 80; j++) {
            if (j < 20) {
                temp = ROTL(A, 5) + ((B & C) | ((~B) & D)) + E + W[j] + K[0];
            } else if (j < 40) {
                temp = ROTL(A, 5) + (B ^ C ^ D) + E + W[j] + K[1];
            } else if (j < 60) {
                temp = ROTL(A, 5) + ((B & C) | (B & D) | (C & D)) + E + W[j] + K[2];
            } else {
                temp = ROTL(A, 5) + (B ^ C ^ D) + E + W[j] + K[3];
            }
            E = D;
            D = C;
            C = ROTL(B, 30);
            B = A;
            A = temp;
        }

        H[0] += A;
        H[1] += B;
        H[2] += C;
        H[3] += D;
        H[4] += E;
    }

    free(block);

    // output digest
    for (i = 0; i < 5; i++) {
        digest[i * 4] = (uint8_t)(H[i] >> 24);
        digest[i * 4 + 1] = (uint8_t)(H[i] >> 16);
        digest[i * 4 + 2] = (uint8_t)(H[i] >> 8);
        digest[i * 4 + 3] = (uint8_t)(H[i]);
    }
}

int main() {
    uint8_t message[] = "hello world";
    uint8_t digest[20];
    sha1(message, strlen(message), digest);
    printf("SHA-1 digest: ");
    for (int i = 0; i < 20; i++) {
        printf("%02x", digest[i]);
    }
    printf("\n");
    return 0;
}

注意，这个实现仅供学习和参考，不应该用于实际应用中。在实际应用中，应该使用经过充分测试和验证的加密库来保证安全性和正确性。