加速密码

Question

这是我用Java编写的密码，但我不知道它是否正常工作，因为当我传递一个文件如.gif时会生成一个较小的输出字符串，当我将其转换回来时，gif不起作用它比原来的几个字节小。我认为这可能是ascii转换的二进制问题。有谁知道如何解决它？

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.math.BigInteger;

public class XOR {

    public static void main(String args[]) throws UnsupportedEncodingException, FileNotFoundException {
        String data = "this is a string";
        String rawKey = "this is a key.".toLowerCase();

        //Checks the key is valid.
        if (rawKey.length() % 2 != 0) {
            System.err.println("The key has to be an even length.");
            System.exit(1);
        }

        for(int p = 0; p < rawKey.length()-1; p++){
            if (rawKey.charAt(p) == rawKey.charAt(p+1)) {
                System.err.println("The key can't have repeated characters next to each other.");
                System.exit(1);
            }
        }

        long dataLength = data.length();
        String content = strToBin(data);

        String working = content;
        for (int i = 0; i < rawKey.length(); i++) {
        working = XOR(working, String.valueOf(strToBin(String.valueOf(rawKey.charAt(i)))), 8, dataLength);
        }
        System.out.println(working);
        System.out.println(binToStr(working));

        for (int i = 0; i < rawKey.length(); i++) {
        working = XOR(working, String.valueOf(strToBin(String.valueOf(rawKey.charAt(i)))), 8, dataLength);
        }
        System.out.println(binToStr(working));
    }

    public static String XOR(String input, String key, int blockSize, long length) {
        long tries = length;
        String original = input; //INPUTS MUST BE IN BINARY
        String compare = key; //INPUTS MUST BE IN BINARY
        String build = "";
        long o = 0; //The offset so we skip characters we have already done.
        for (int t = 0; t < tries; t++) { //Do each block.
        for(int i = 0; i < blockSize; i++) { //Do each block one at a time.
            if (original.charAt((int) (i+o)) == compare.charAt(i)) { //Compares the block to the key
                build += "0"; //If the key and the character are the same false.
            } else {
                build += "1"; //If the key and the character are the different true.
            }
        }
        o += blockSize+1; //+1 to include the space.
        if (t != tries-1) {build += " ";}; //Adds space. If statement prevents adding a pointless space onto the end.
        }
        return build;
    }

    public static String strToBin(String input) {
      byte[] bytes = input.getBytes();
      StringBuilder binary = new StringBuilder();
      for (byte b : bytes)
      {
         int val = b;
         for (int i = 0; i < 8; i++)
         {
            binary.append((val & 128) == 0 ? 0 : 1);
            val <<= 1;
         }
         binary.append(' ');
      }
      return binary.toString();
    }

    public static String binToStr( String s ) { 
        String[] ss = s.split(" ");
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < ss.length; i++) { 
            sb.append( (char)Integer.parseInt( ss[i], 2 ) );                                                                                                                                                        
        }   
        return sb.toString();
    } 
}