对文件进行对称的DES加密

package com.ivan.security.algorithm;

/**
 * 对字符流进行对称的DES加密
 * @author Ivan
 * @DataTime 2006-12-11 12:34
 *
 */

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.security.NoSuchAlgorithmException;
import java.security.Security;

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

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

import com.iuxi.security.util.*;

public class DESUtil ...{
    
    private static String Algorithm = "DESede"; //"DESede" for Triple DES
    private static KeyGenerator keyGen = null;
    private static SecretKey desKey = null;
    private static Cipher c = null;
    private static byte[] cipherByte = null;
    
    public DESUtil() ...{
        init();
    }
    
    public static void init() ...{
        try ...{
            c = Cipher.getInstance(Algorithm);
        } catch (NoSuchAlgorithmException e) ...{
            System.err.println("初始化错误，原因：所指定的算法无效！");
            e.printStackTrace();
        } catch (NoSuchPaddingException e) ...{
            e.printStackTrace();
        }
    }

    public static String getAlgorithm() ...{
        return Algorithm;
    }

    public static void setAlgorithm(String algorithm) ...{
        DESUtil.Algorithm = algorithm;
    }
    
    public static void setDesKey (SecretKey desKey) ...{
        DESUtil.desKey = desKey;
    }

    /** *//**
     * 保存密钥信息到磁盘
     * @param filepath 保存路径
     * @return
     */
    public static void saveKey(String filePath) ...{
        if (desKey != null) ...{
            try ...{
                FileOutputStream fos = new FileOutputStream(filePath);
                ObjectOutputStream oos = new ObjectOutputStream(fos);
                oos.writeObject(desKey);
            }catch (IOException e) ...{
                System.err.println("保存密钥信息出错！");
                e.printStackTrace();
            }
        }
        else ...{
            System.err.println("保存密钥失败，密钥不存在！");
        }
    }
    
    /** *//**
     * 从磁盘读取密钥信息
     * @param filePath
     * @return
     */
    public static SecretKey readKey(String filePath) ...{
        try ...{
            FileInputStream fis = new FileInputStream(filePath);
            fis = new FileInputStream(filePath);
            ObjectInputStream ois = new ObjectInputStream(fis);
            desKey = (SecretKey) ois.readObject();
            ois.close();
            fis.close();
        }catch (FileNotFoundException e) ...{
            System.err.println("读取密钥信息出错，原因：找不到指定的文件！");
        } catch (IOException ex) ...{
            System.err.println("读取密钥信息出错，原因：IO错误！");
            ex.printStackTrace();
        } catch (Exception ex) ...{
            ex.printStackTrace();
        }
        return desKey;
    }
    
    /** *//**
     * 按照指定的算法生成密钥
     * @param algorithm 所指定的算法
     * @return 生成的密钥
     */
    public static SecretKey genKey (String algorithm) ...{
        try ...{
            keyGen = KeyGenerator.getInstance(algorithm);
        } catch (NoSuchAlgorithmException e) ...{
            System.err.println("生成密钥失败，原因：所指定的算法无效！");
            e.printStackTrace();
        }
        desKey = keyGen.generateKey();
        return desKey;
    }
    
    /** *//**
     * 加密已转化为字节串的字符流
     * @param rawByte 原始字节串
     * @return 加密后的字节串
     */
    public static byte[] encryptData(byte[] rawByte) ...{
        if(desKey != null) ...{
            try ...{
                c.init(Cipher.ENCRYPT_MODE, desKey);
                cipherByte = c.doFinal(rawByte);
            } catch (java.security.InvalidKeyException ex) ...{
                System.err.println("加密失败，密钥无效!");
                ex.printStackTrace();
            } catch (javax.crypto.BadPaddingException ex) ...{
                System.err.println("加密失败!");
                ex.printStackTrace();
            } catch (javax.crypto.IllegalBlockSizeException ex) ...{
                System.err.println("加密失败!");
                ex.printStackTrace();
            } catch (Exception ex) ...{
                System.err.println("加密失败!");
                ex.printStackTrace();
            }
        }
        else ...{
            System.err.println("加密失败，原因：密钥不存在！");
        }
        return cipherByte;
    }
    
    /** *//**
     * 解密字节串
     * @param cipherByte 密文字节串
     * @return 解密后的字节串
     */
    public static byte[] decryptor(byte[] cipherByte) ...{
        if(desKey != null) ...{
            try ...{
                c.init(Cipher.DECRYPT_MODE, desKey);
                cipherByte = c.doFinal(cipherByte);
            } catch (java.security.InvalidKeyException ex) ...{
                ex.printStackTrace();
            } catch (javax.crypto.BadPaddingException ex) ...{
                ex.printStackTrace();
            } catch (javax.crypto.IllegalBlockSizeException ex) ...{
                ex.printStackTrace();
            } catch (Exception ex) ...{
                ex.printStackTrace();
            }
            return (cipherByte);
        }
        else ...{
            System.err.println("解密失败，原因：密钥不存在！");
            return null;
        }
    }
    
    public static void main(String[] args) throws Exception ...{
        DESUtil.init();
        DESUtil.genKey("DESede");
        DESUtil.saveKey("desKey.dat");
        byte[] cipherData = DESUtil.encryptData("This is just a test!".getBytes());
        
        String cipherString = new String(new BASE64Encoder().encode(cipherData));
        System.out.println("密文数据为：" + cipherString);
        
        byte[] cipherByte = new BASE64Decoder().decodeBuffer(cipherString);
        String rawString = new String(DESUtil.decryptor(cipherByte));
        System.out.println("解密后的原文为：" + rawString); 
    }

}