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我需要使用种子:1 2 3 6和明文密码学来实现Rc4算法。我遵循了我们在课堂上提供的这个指导原则,但它并没有正确初始化S。 实现Rc4算法
我的代码是以前印刷负值,不知道为什么,但我设法解决这个错误。以为一切都很好,但事实并非如此。对于图片抱歉,我认为解释我的代码结构是如何更容易。我是mod 4的种子,因为它包含4个字符,这可能是我的错误吗?
#include <iostream>
#include <string>
#include <string.h>
using std::endl;
using std::string;
void swap(unsigned int *x, unsigned int *y);
int main()
{
string plaintext = "cryptology";
char cipherText[256] = { ' ' };
unsigned int S[256] = { 0 };
unsigned int t[256] = { 0 };
unsigned int seed[4] = { 1, 2, 3, 6 }; // seed used for test case 1
unsigned int temp = 0;
int runningTotal = 0;
unsigned int key = 0;
// inilializing s and t
for (int i = 0; i < 256; i++)
{
S[i] = i;
t[i] = seed[i % 4];
}
for (int i = 0; i < 256; i++)
{
runningTotal += S[i] + t[i];
runningTotal %= 256;
swap(&S[runningTotal], &S[i]);
std::cout << S[i] <<" ";
}
runningTotal = 0;
for (int i = 0; i < plaintext.size(); i++)
{
runningTotal %= 256;
swap(&S[i], &S[runningTotal]);
temp = (unsigned int)S[i] + (unsigned int)S[runningTotal];
temp %= 256;
key = S[temp];
std::cout << endl;
cipherText[i] = plaintext[i]^key;
}
std::cout << " this is cipher text " << endl;
std::cout << cipherText << endl;
system("pause");
return 0;
}
void swap(unsigned int *x, unsigned int *y)
{
unsigned int temp = 0;
temp = *x;
*x = *y;
*y = temp;
}