caesar chiper c++

#include <cstdlib>
#include <iostream>
#include <string.h>
#define maks 500
using namespace std;

//int main(int argc, char *argv[])
class Enskripsi
{
      public:
             Enskripsi();
      void enskripsi();
      void deskripsi();
      void output();
      private:
              char chiper[maks];
              int key;
              char plain[maks];
              };
              Enskripsi::Enskripsi(){
              cout<<"masukkan kata:";
              cin.getline(chiper,sizeof(chiper));
              cout<<"masukkan key:";
              cin>>key;
              cout<<endl;
              }
             
      void Enskripsi::enskripsi(){
           for(int i=0;i<strlen(chiper);i+=1){
                   cout<<chiper[i]<<" ("<<int(chiper[i])<<") ";
                   chiper[i]=(chiper[i]+key)%128;
                   }}
                  
           void Enskripsi::deskripsi(){
                for(int i=0;i<strlen(chiper);i+=1){
                plain[i]=(chiper[i]-key)%128;
                chiper[i]=plain[i];
                }}
               
           void Enskripsi::output(){
           for(int i=0;i<strlen(chiper);i+=1){
                   cout<<chiper[i];
                   }}
                   int main(int argc, char *argv[])
                   {
                       Enskripsi Deskripsi;
                       Deskripsi.enskripsi();
                       cout<<"\n\nsetelah dienskripsi:";
                       Deskripsi.output();
                       Deskripsi.deskripsi();
                       cout<<"\n\nkembali dideskripsi:";
                       Deskripsi.output();
                      
                   cout<<endl<<endl;
                  
    system("PAUSE");
    return EXIT_SUCCESS;
}