C++的md5函数 - 技术栈

在项目中，让AI生成的MD5的C++版本，通过了测试，所以放到这里，供后续直接拷贝使用，毕竟AI生成的总是需要验证后才能使用。

调用方法很简单：

cpp 复制代码

string str = "hello";
cout << MD5::md5(str) << endl;

cpp 复制代码

#pragma once

#include <algorithm>
#include <iomanip>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>

class MD5 {
private:
    typedef struct {
        uint32_t count[2];
        uint32_t state[4];
        uint8_t buffer[64];
    } MD5_CTX;

#define F(x, y, z) ((x & y) | (~x & z))
#define G(x, y, z) ((x & z) | (y & ~z))
#define H(x, y, z) (x ^ y ^ z)
#define I(x, y, z) (y ^ (x | ~z))
#define ROTATE_LEFT(x, n) ((x << n) | (x >> (32 - n)))

#define FF(a, b, c, d, x, s, ac)  \
    {                             \
        a += F(b, c, d) + x + ac; \
        a = ROTATE_LEFT(a, s);    \
        a += b;                   \
    }
#define GG(a, b, c, d, x, s, ac)  \
    {                             \
        a += G(b, c, d) + x + ac; \
        a = ROTATE_LEFT(a, s);    \
        a += b;                   \
    }
#define HH(a, b, c, d, x, s, ac)  \
    {                             \
        a += H(b, c, d) + x + ac; \
        a = ROTATE_LEFT(a, s);    \
        a += b;                   \
    }
#define II(a, b, c, d, x, s, ac)  \
    {                             \
        a += I(b, c, d) + x + ac; \
        a = ROTATE_LEFT(a, s);    \
        a += b;                   \
    }

    static void MD5Init(MD5_CTX *context);
    static void MD5Update(MD5_CTX *context, unsigned char *input, uint32_t inputlen);
    static void MD5Final(unsigned char digest[16], MD5_CTX *context);
    static void MD5Transform(uint32_t state[4], unsigned char block[64]);
    static void Encode(unsigned char *output, uint32_t *input, uint32_t len);
    static void Decode(uint32_t *output, unsigned char *input, uint32_t len);

public:
    static std::string md5(const std::string &input);
};

void MD5::MD5Init(MD5_CTX *context) {
    context->count[0] = 0;
    context->count[1] = 0;
    context->state[0] = 0x67452301;
    context->state[1] = 0xEFCDAB89;
    context->state[2] = 0x98BADCFE;
    context->state[3] = 0x10325476;
}

void MD5::MD5Update(MD5_CTX *context, unsigned char *input, uint32_t inputlen) {
    uint32_t i = 0, index = 0, partlen = 0;
    index = (context->count[0] >> 3) & 0x3F;
    if ((context->count[0] += inputlen << 3) < (inputlen << 3)) {
        context->count[1]++;
    }
    context->count[1] += inputlen >> 29;
    partlen = 64 - index;
    if (inputlen >= partlen) {
        std::memcpy(&context->buffer[index], input, partlen);
        MD5Transform(context->state, context->buffer);
        for (i = partlen; i + 63 < inputlen; i += 64) {
            MD5Transform(context->state, &input[i]);
        }
        index = 0;
    } else {
        i = 0;
    }
    std::memcpy(&context->buffer[index], &input[i], inputlen - i);
}

void MD5::MD5Final(unsigned char digest[16], MD5_CTX *context) {
    unsigned char bits[8];
    uint32_t index = 0, padlen = 0;
    Encode(bits, context->count, 8);
    index = (context->count[0] >> 3) & 0x3f;
    padlen = (index < 56) ? (56 - index) : (120 - index);
    MD5Update(context, (unsigned char *)"\x80", 1);
    for (uint32_t i = 0; i < padlen - 1; i++) {
        MD5Update(context, (unsigned char *)"\0", 1);
    }
    MD5Update(context, bits, 8);
    Encode(digest, context->state, 16);
}

void MD5::MD5Transform(uint32_t state[4], unsigned char block[64]) {
    uint32_t a = state[0], b = state[1], c = state[2], d = state[3], x[64];
    Decode(x, block, 64);

    FF(a, b, c, d, x[0], 7, 0xd76aa478);
    FF(d, a, b, c, x[1], 12, 0xe8c7b756);
    FF(c, d, a, b, x[2], 17, 0x242070db);
    FF(b, c, d, a, x[3], 22, 0xc1bdceee);
    FF(a, b, c, d, x[4], 7, 0xf57c0faf);
    FF(d, a, b, c, x[5], 12, 0x4787c62a);
    FF(c, d, a, b, x[6], 17, 0xa8304613);
    FF(b, c, d, a, x[7], 22, 0xfd469501);
    FF(a, b, c, d, x[8], 7, 0x698098d8);
    FF(d, a, b, c, x[9], 12, 0x8b44f7af);
    FF(c, d, a, b, x[10], 17, 0xffff5bb1);
    FF(b, c, d, a, x[11], 22, 0x895cd7be);
    FF(a, b, c, d, x[12], 7, 0x6b901122);
    FF(d, a, b, c, x[13], 12, 0xfd987193);
    FF(c, d, a, b, x[14], 17, 0xa679438e);
    FF(b, c, d, a, x[15], 22, 0x49b40821);

    GG(a, b, c, d, x[1], 5, 0xf61e2562);
    GG(d, a, b, c, x[6], 9, 0xc040b340);
    GG(c, d, a, b, x[11], 14, 0x265e5a51);
    GG(b, c, d, a, x[0], 20, 0xe9b6c7aa);
    GG(a, b, c, d, x[5], 5, 0xd62f105d);
    GG(d, a, b, c, x[10], 9, 0x2441453);
    GG(c, d, a, b, x[15], 14, 0xd8a1e681);
    GG(b, c, d, a, x[4], 20, 0xe7d3fbc8);
    GG(a, b, c, d, x[9], 5, 0x21e1cde6);
    GG(d, a, b, c, x[14], 9, 0xc33707d6);
    GG(c, d, a, b, x[3], 14, 0xf4d50d87);
    GG(b, c, d, a, x[8], 20, 0x455a14ed);
    GG(a, b, c, d, x[13], 5, 0xa9e3e905);
    GG(d, a, b, c, x[2], 9, 0xfcefa3f8);
    GG(c, d, a, b, x[7], 14, 0x676f02d9);
    GG(b, c, d, a, x[12], 20, 0x8d2a4c8a);

    HH(a, b, c, d, x[5], 4, 0xfffa3942);
    HH(d, a, b, c, x[8], 11, 0x8771f681);
    HH(c, d, a, b, x[11], 16, 0x6d9d6122);
    HH(b, c, d, a, x[14], 23, 0xfde5380c);
    HH(a, b, c, d, x[1], 4, 0xa4beea44);
    HH(d, a, b, c, x[4], 11, 0x4bdecfa9);
    HH(c, d, a, b, x[7], 16, 0xf6bb4b60);
    HH(b, c, d, a, x[10], 23, 0xbebfbc70);
    HH(a, b, c, d, x[13], 4, 0x289b7ec6);
    HH(d, a, b, c, x[0], 11, 0xeaa127fa);
    HH(c, d, a, b, x[3], 16, 0xd4ef3085);
    HH(b, c, d, a, x[6], 23, 0x4881d05);
    HH(a, b, c, d, x[9], 4, 0xd9d4d039);
    HH(d, a, b, c, x[12], 11, 0xe6db99e5);
    HH(c, d, a, b, x[15], 16, 0x1fa27cf8);
    HH(b, c, d, a, x[2], 23, 0xc4ac5665);

    II(a, b, c, d, x[0], 6, 0xf4292244);
    II(d, a, b, c, x[7], 10, 0x432aff97);
    II(c, d, a, b, x[14], 15, 0xab9423a7);
    II(b, c, d, a, x[5], 21, 0xfc93a039);
    II(a, b, c, d, x[12], 6, 0x655b59c3);
    II(d, a, b, c, x[3], 10, 0x8f0ccc92);
    II(c, d, a, b, x[10], 15, 0xffeff47d);
    II(b, c, d, a, x[1], 21, 0x85845dd1);
    II(a, b, c, d, x[8], 6, 0x6fa87e4f);
    II(d, a, b, c, x[15], 10, 0xfe2ce6e0);
    II(c, d, a, b, x[6], 15, 0xa3014314);
    II(b, c, d, a, x[13], 21, 0x4e0811a1);
    II(a, b, c, d, x[4], 6, 0xf7537e82);
    II(d, a, b, c, x[11], 10, 0xbd3af235);
    II(c, d, a, b, x[2], 15, 0x2ad7d2bb);
    II(b, c, d, a, x[9], 21, 0xeb86d391);

    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
}

void MD5::Encode(unsigned char *output, uint32_t *input, uint32_t len) {
    for (uint32_t i = 0, j = 0; j < len; i++, j += 4) {
        output[j] = (unsigned char)(input[i] & 0xff);
        output[j + 1] = (unsigned char)((input[i] >> 8) & 0xff);
        output[j + 2] = (unsigned char)((input[i] >> 16) & 0xff);
        output[j + 3] = (unsigned char)((input[i] >> 24) & 0xff);
    }
}

void MD5::Decode(uint32_t *output, unsigned char *input, uint32_t len) {
    for (uint32_t i = 0, j = 0; j < len; i++, j += 4) {
        output[i] = ((uint32_t)input[j]) |
                    (((uint32_t)input[j + 1]) << 8) |
                    (((uint32_t)input[j + 2]) << 16) |
                    (((uint32_t)input[j + 3]) << 24);
    }
}

std::string MD5::md5(const std::string &input) {
    MD5_CTX context;
    unsigned char digest[16];
    MD5Init(&context);
    MD5Update(&context, (unsigned char *)input.c_str(), input.length());
    MD5Final(digest, &context);

    std::stringstream ss;
    for (int i = 0; i < 16; i++) {
        ss << std::hex << std::setw(2) << std::setfill('0') << (int)digest[i];
    }
    return ss.str();
}