== 암호화 ==
{{{~cpp 
#include <fstream>
#include <iostream>
using namespace std;
void main()
{
	ifstream fin ("source.txt");
	ofstream fout ("source_enc.txt");
	int x;
	cout << "KEY 값을 입력하세요 : "
	cin >> x;
	int temp;
	char ch;
	do{
		fin.get(ch);
		temp = (int) ch;
		fout << char(temp-x);
	}while(!(fin.eof()));
}
}}}

== 복호화 ==
{{{~cpp 
#include <iostream>
#include <fstream>
using namespace std;
void main()
{
	ifstream fin("source_enc.txt");
	ofstream fout("normal.txt");
	int y;
	cout << "복호화 할 KEY 값을 입력하세요";
	cin >> y;
	int temp;
	char ch;
	do{
		fin.get(ch);
		temp = (int) ch;
		fout << char(temp+y);
	}while(!(fin.eof()));
}
}}}