C++编程实现RC4密码算法

下面是C++实现的RC4密码算法代码：

#include <iostream>
#include <cstring>

using namespace std;

void rc4_init(unsigned char* key_data_ptr, int key_data_len, unsigned char* key, int key_len) {
    int i, j;
    unsigned char t;
    for (i = 0; i < 256; i++) {
        key[i] = key_data_ptr[i % key_data_len];
    }
    for (i = 0, j = 0; i < 256; i++) {
        j = (j + key[i] + i) % 256;
        t = key[i];
        key[i] = key[j];
        key[j] = t;
    }
}

void rc4_crypt(unsigned char* data, int data_len, unsigned char* key, int key_len) {
    int i, j, k;
    unsigned char t;
    for (i = 0, j = 0; i < data_len; i++) {
        j = (j + 1) % 256;
        k = (k + key[j]) % 256;
        t = key[j];
        key[j] = key[k];
        key[k] = t;
        data[i] ^= key[(key[j] + key[k]) % 256];
    }
}

int main() {
    unsigned char key_data[] = "password";
    unsigned char data[] = "hello world!";
    unsigned char key[256];
    int key_len = strlen((char*)key_data);
    int data_len = strlen((char*)data);
    rc4_init(key_data, key_len, key, 256);
    rc4_crypt(data, data_len, key, 256);
    cout << "Encrypted data: " << data << endl;
    rc4_init(key_data, key_len, key, 256);
    rc4_crypt(data, data_len, key, 256);
    cout << "Decrypted data: " << data << endl;
    return 0;
}

该代码实现了RC4密码算法的初始化和加解密操作。在初始化函数中，使用密钥数据对密钥数组进行初始化，然后使用密钥数组进行密钥调度；在加解密函数中，通过对密钥数组进行变换，生成伪随机数流，并使用该流对明文进行加密或密文进行解密。