RC4加密算法

[code]#include <iostream>
#include <cstring>
#include <cstdio>
#include <map>
#include <algorithm>

using namespace std;

int S[300];
int T[300];
int K[300];

int main()
{
    int len;
    scanf("%d", &len);
    for (int i = 0;i < len;i++) scanf("%d",&K[i]);
    for (int i = 0;i <= 255;i++)
    {
        S[i] = i;
        T[i] = K[i%len];
    }
    int j = 0;
    for (int i = 0;i <= 255;i++)
    {
        j = (j + S[i] + T[i]) % 256;
        swap(S[i], S[j]);
    }

    int clear_text[300];
    int cnt;
    scanf("%d", &cnt);
    for (int i = 0;i < cnt;i++) scanf("%d", &clear_text[i]);
    int tmp[300];
    int num = 0;

    int i = 0;
    j = 0;
    while (1)
    {
        i = (i + 1) % 256;
        j = (j + S[i]) % 256;
        swap(S[i], S[j]);
        int t = (S[i] + S[j]) % 256;
        tmp[num++] = S[t];
        if (num == cnt) break;
    }
    int ans[300];
    for (int i = 0;i < strlen(clear_text);i++)
        ans[i] = (tmp[i] ^ clear_text[i]);
    for (int i = 0;i < strlen(clear_text);i++) cout << ans[i] << " ";cout << endl;
    return 0;
}