Java加解密

• 介绍

本文介绍如何利用Java语言加密数据。

• 对称加密
• DES（Data Encryption Standard）

[codesyntax lang="java"]

/**
* Copyright © 1998-2015, surenpi.com All Rights Reserved.
*/
package org.suren.hibernate.util;

import java.io.ByteArrayOutputStream;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;

/**
 * @author suren
 * @date 2015年11月24日 下午5:04:05
 */
public class Encryptor
{
  private KeyGenerator  keyGen;
  private SecretKey key;
  private Cipher  cipher;
  private byte[]  cipherByte;
  
  public static final String ALG_DES = "DES";
  private static Encryptor encryptor;
  
  private Encryptor(){}
  
  private Encryptor(String algorithm) throws NoSuchAlgorithmException, NoSuchPaddingException
  {
    keyGen = KeyGenerator.getInstance(algorithm);
    key = keyGen.generateKey();
    
    cipher = Cipher.getInstance(algorithm);
  }
  
  public static Encryptor getInstance(String algorithm) throws NoSuchAlgorithmException, NoSuchPaddingException
  {
    if(encryptor == null)
    {
      encryptor = new Encryptor(algorithm);
    }
    
    return encryptor;
  }
  
  public byte[] encrypt(String str) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException
  {
    cipher.init(Cipher.ENCRYPT_MODE, key);
    cipherByte = cipher.doFinal(str.getBytes());
    return cipherByte;
  }
  
  public String encryptStr(String str) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException
  {
    byte[] encryptArray = encrypt(str);
    
    StringBuffer strBuf = new StringBuffer();
    for(byte e : encryptArray)
    {
      strBuf.append(intToChar((e >> 4) & 0x0f));
      strBuf.append(intToChar(e & 0x0f));
    }
    
    return strBuf.toString();
  }
  
  public byte[] decrypt(byte[] buf) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException
  {
    cipher.init(Cipher.DECRYPT_MODE, key);
    cipherByte = cipher.doFinal(buf);
    return cipherByte;
  }
  
  public String decryptStr(byte[] buf) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException
  {
    return new String(decrypt(buf));
  }
  
  /**
   * decrypt string
   * @see #encryptStr(String)
   * @param encryptStr
   * @return
   * @throws InvalidKeyException
   * @throws IllegalBlockSizeException
   * @throws BadPaddingException
   * @throws NullPointerException if encryptStr is null
   */
  public String decryptStr(String encryptStr) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException
  {
    if(encryptStr == null)
    {
      throw new NullPointerException();
    }
    
    encryptStr = encryptStr.toUpperCase();
    
    ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
    int len = encryptStr.length();
    for(int i = 0; i < len; i += 2)
    {
      int b = ((charToByte(encryptStr.charAt(i)) << 4) & 0xff) | charToByte(encryptStr.charAt(i + 1));
      byteOut.write(b);
    }
    
    return decryptStr(byteOut.toByteArray());
  }
  
  private byte charToByte(char c)
  {
    return (byte) "0123456789ABCDEF".indexOf(c);
  }
  
  private char intToChar(int b)
  {
    return "0123456789ABCDEF".charAt(b);
  }
  
  public void clean()
  {
    cipherByte = null;
  }
}

[/codesyntax]

• 3DES
• AES（Advanced Encryption Standard）
• ​​BASE64​​
• 非对称加密
• RSA
• DSA（Digital Signature Algorithm）
• 参考

​​http://www.iteye.com/topic/1122076/​​

​