怎样用java给文件加密和解密

Question

JAVA上加密算法的实现用例
http://www-900.ibm.com/developerWorks/java/l-security/index.shtml

Answer 1

package encryption;/**
 * Title:
 * Description:
 * Copyright:    Copyright (c) 2001
 * Company:
 * @author
 * @version 1.0
 */
import java.io.*;
import java.math.BigInteger;
import java.security.*;
import java.security.spec.*;
import java.security.interfaces.*;
import javax.crypto.*;
import javax.crypto.spec.*;
import javax.crypto.interfaces.*;public class En1 {    public En1() {        KeyGenerator keygen;
        SecretKey desKey;
        Cipher desCipher;        try{
            //DES,DESede,PBEWithMD5AndDES,Blowfish
            //Generating a Key
//            keygen = KeyGenerator.getInstance("DES");
//            keygen = KeyGenerator.getInstance("DESede");
            keygen = KeyGenerator.getInstance("Blowfish");            desKey = keygen.generateKey();
            System.out.println(
                desKey.getEncoded().toString()
            );            // Create the cipher
//            desCipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
//            desCipher = Cipher.getInstance("DESede");
            desCipher = Cipher.getInstance("Blowfish");
            // Our cleartext
            byte[] cleartext = "This is just an example:邢战军".getBytes();
            StringBuffer StrBuf = new StringBuffer();
            for(int i=0,j=cleartext.length;i<j;i++)
            {
                StrBuf.append(String.valueOf((char)cleartext[i]));
            }
            System.out.println(" ");
            System.out.println(StrBuf.toString());            //Initialize the cipher for encryption
            desCipher.init(Cipher.ENCRYPT_MODE,desKey);            // Encrypt the cleartext
            StrBuf = new StringBuffer();
            byte[] ciphertext = desCipher.doFinal(cleartext);
//            System.out.println(ciphertext.toString());
            for(int i=0,j=ciphertext.length;i<j;i++)
            {
                StrBuf.append(String.valueOf((char)ciphertext[i]));
            }
            System.out.println(" ");
            System.out.println("Encrypt the cleartext");
            System.out.println(StrBuf.toString());            SecretKeySpec seckey = new javax.crypto.spec.SecretKeySpec(
                desKey.getEncoded(),"Blowfish");
            System.out.println(
                seckey.getEncoded()
            );            seckey = new javax.crypto.spec.SecretKeySpec(
                seckey.getEncoded(),"Blowfish");
            System.out.println(
                seckey.getEncoded()
            );            // Initialize the same cipher for decryption
//            desCipher.init(Cipher.DECRYPT_MODE, desKey);
            desCipher.init(Cipher.DECRYPT_MODE, seckey);            // Decrypt the ciphertext
            StrBuf = new StringBuffer();
            byte[] cleartext1 = desCipher.doFinal(ciphertext);
//            System.out.println(cleartext1.toString());
            for(int i=0,j=cleartext1.length;i<j;i++)
            {
                StrBuf.append(String.valueOf((char)cleartext1[i]));
            }
            System.out.println(" ");
            System.out.println("Decrypt the ciphertext");
            System.out.println(StrBuf.toString());
        }
        catch(java.security.InvalidKeyException e2)
        {
            e2.printStackTrace();
        }
        catch(java.security.NoSuchAlgorithmException e)
        {
            e.printStackTrace();
        }
        catch(javax.crypto.NoSuchPaddingException e1)
        {
            e1.printStackTrace();
        }
        catch(javax.crypto.BadPaddingException e3)
        {
            e3.printStackTrace();
        }
        catch(javax.crypto.IllegalBlockSizeException e4)
        {
            e4.printStackTrace();
        }    }    public static void main(String[] args) {
        En1 en11 = new En1();
    }
}

Answer 2

import javax.crypto.*;
在哪个JAR里?