import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;


public class demo {
    static char[] bitcode(char[] str, char n)                //位加密解密演算法
    {
        int i, len;
        char[] wen;

        len = str.length;
        if ((wen = new
 
 char[len + 1]) == null) {
            System.out.print("申請記憶體失敗!\n");
            System.exit(1);
        }
        for (i = 0; i < len; i++) {
            wen[i] = (char) (str[i] ^ n);                    //異或運算
        }
        wen[len] = '\0';
        return wen;
    }

    public static void main(String[] args) throws
 
 IOException {
        int i;
        char ch;
        char[] srcstr = new char[100];
        char[] miwen;
        String go;

        System.out.print("位加密解密演算法演示！\n");

        do {
            System.out.print("\n請先輸入替換加密解密演算法中的金鑰：");
            Scanner input = new Scanner(System.in);
            ch 
 
= input.next().charAt(0);                        //金鑰
            System.out.print("請輸入明文字串：");

            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
            String str = bufferedReader.readLine();
            srcstr = str.toCharArray();                //明文字串

            System.out.print("輸入的明文為：");
            for (i = 0; i < srcstr.length; i++) {
                System.out.print(srcstr[i]);
            }

            miwen = bitcode(srcstr, ch);                //加密
            System.out.print("\n加密後的密文為：");
            for (i = 0; i < srcstr.length; i++) {
                System.out.print(miwen[i]);
            }
            miwen = bitcode(miwen, ch);                //解密
            System.out.print("\n解密出的明文為：");
            for (i = 0; i < srcstr.length; i++) {
                System.out.print(miwen[i]);
            }

            System.out.print("\n繼續執行(y/n)?");
            go = input.next();
        } while (go.equalsIgnoreCase("y"));
        System.out.println("演示結束！");

    }

}