JAVA 암호화 복호화

public class Crypto{
    /**
     * 파일암호화에 쓰이는 버퍼 크기 지정
     */
    public static final int kBufferSize = 8192;
 public static java.security.Key key = null;
 public static final String defaultkeyfileurl = "defaultkey.key";
 /**
     * 비밀키 생성메소드
     * @return  void
     * @exception java.io.IOException,java.security.NoSuchAlgorithmException
     */
 public static java.io.File makekey() throws java.io.IOException,java.security.NoSuchAlgorithmException{
  return makekey(defaultkeyfileurl);
 }
 public static java.io.File makekey(String filename) throws java.io.IOException,java.security.NoSuchAlgorithmException{
  java.io.File tempfile = new java.io.File(".",filename);
  javax.crypto.KeyGenerator generator = javax.crypto.KeyGenerator.getInstance("DES");
  generator.init(new java.security.SecureRandom());
  java.security.Key key = generator.generateKey();
  java.io.ObjectOutputStream out = new java.io.ObjectOutputStream(new java.io.FileOutputStream(tempfile));
  out.writeObject(key);
  out.close();
  return tempfile;
 }

    /**
     * 지정된 비밀키를 가지고 오는 메서드
     * @return  Key 비밀키 클래스
     * @exception Exception
     */
    private static java.security.Key getKey()
    throws Exception{
        if(key != null){
   return key;
  }else{
   return getKey(defaultkeyfileurl);
  }
    }
 private static java.security.Key getKey(String fileurl)
    throws Exception{
  if(key == null){
   java.io.File file = new java.io.File(fileurl);
   if(!file.exists()){
    file = makekey();
   }
   if(file.exists()){
    java.io.ObjectInputStream in = new java.io.ObjectInputStream(new java.io.FileInputStream(fileurl));
    key = (java.security.Key)in.readObject();
    in.close();
   }else{
    throw new Exception("암호키객체를 생성할 수 없습니다.");
   }
  }
        return key;
    }
 
    /**
     * 문자열 대칭 암호화
     * @param   ID  비밀키 암호화를 희망하는 문자열
     * @return  String  암호화된 ID
     * @exception Exception
     */
 public static String encrypt(String ID)
  throws Exception{
   if ( ID == null || ID.length() == 0 ) return "";
   javax.crypto.Cipher cipher = javax.crypto.Cipher.getInstance("DES/ECB/PKCS5Padding");
   cipher.init(javax.crypto.Cipher.ENCRYPT_MODE,getKey());
   String amalgam = ID;
 
   byte[] inputBytes1 = amalgam.getBytes("UTF8");
   byte[] outputBytes1 = cipher.doFinal(inputBytes1);
   sun.misc.BASE64Encoder encoder = new sun.misc.BASE64Encoder();       
   String outputStr1 = encoder.encode(outputBytes1);
   return outputStr1;
 }
 
    /**
     * 문자열 대칭 복호화
     * @param   codedID  비밀키 복호화를 희망하는 문자열
     * @return  String  복호화된 ID
     * @exception Exception
     */
 public static String decrypt(String codedID)
  throws Exception{
   if ( codedID == null || codedID.length() == 0 ) return "";
   javax.crypto.Cipher cipher = javax.crypto.Cipher.getInstance("DES/ECB/PKCS5Padding");
   cipher.init(javax.crypto.Cipher.DECRYPT_MODE, getKey());
   sun.misc.BASE64Decoder decoder = new sun.misc.BASE64Decoder();
 
   byte[] inputBytes1  = decoder.decodeBuffer(codedID);
   byte[] outputBytes2 = cipher.doFinal(inputBytes1);
 
   String strResult = new String(outputBytes2,"UTF8");
   return strResult;
 }
 
    /**
     * 파일 대칭 암호화
     * @param   infile 암호화을 희망하는 파일명
     * @param   outfile 암호화된 파일명
     * @exception Exception
     */
    public static void encryptFile(String infile, String outfile)
    throws Exception{
            javax.crypto.Cipher cipher = javax.crypto.Cipher.getInstance("DES/ECB/PKCS5Padding");
            cipher.init(javax.crypto.Cipher.ENCRYPT_MODE,getKey());
 
            java.io.FileInputStream in = new java.io.FileInputStream(infile);
            java.io.FileOutputStream fileOut = new java.io.FileOutputStream(outfile);
 
            javax.crypto.CipherOutputStream out = new javax.crypto.CipherOutputStream(fileOut, cipher);
            byte[] buffer = new byte[kBufferSize];
            int length;
            while((length = in.read(buffer)) != -1)
                    out.write(buffer,0,length);
            in.close();
            out.close();
    }
    /**
     * 파일 대칭 복호화
     * @param   infile 복호화을 희망하는 파일명
     * @param   outfile 복호화된 파일명
     * @exception Exception
     */
    public static void decryptFile(String infile, String outfile)
    throws Exception{
            javax.crypto.Cipher cipher = javax.crypto.Cipher.getInstance("DES/ECB/PKCS5Padding");
            cipher.init(javax.crypto.Cipher.DECRYPT_MODE,getKey());
 
            java.io.FileInputStream in = new java.io.FileInputStream(infile);
            java.io.FileOutputStream fileOut = new java.io.FileOutputStream(outfile);
 
            javax.crypto.CipherOutputStream out = new javax.crypto.CipherOutputStream(fileOut, cipher);
            byte[] buffer = new byte[kBufferSize];
            int length;
            while((length = in.read(buffer)) != -1)
                    out.write(buffer,0,length);
            in.close();
            out.close();
    }
   
    public static void main(String[] ars)
    throws Exception {
        if(ars.length < 2) {
            System.out.println("USE : java com.crypto.Crypto [-d | -e | -fd | -fe] [text | inputfilename outputfilename]");
            System.exit(0);
        }
        if(ars[0].equals("-d"))
            System.out.println(Crypto.decrypt(ars[1]));
 
        if(ars[0].equals("-e"))
            System.out.println(Crypto.encrypt(ars[1]));
 
        if(ars[0].equals("-fd"))
            Crypto.decryptFile(ars[1], ars[2]);
 
        if(ars[0].equals("-fe"))
            Crypto.encryptFile(ars[1], ars[2]);
 
    }
}