java文件加密器源代码,java实现文件加密解密

用java写个文件加密的代码该怎么写

最简单的就一个FOR循环要加密的文件 再声明一个字符串 遍历 要加密的文件和字符串进行位与操作或之类操作

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类似这样-

import java.util.Arrays;

public class Test {

public static void main(String[] args) {

String str = "hello";

byte[] strCode = str.getBytes();

System.out.println("原始信息字节码："+Arrays.toString(strCode));

String key = "abcde";

byte[] keyCode = key.getBytes();

System.out.println("密钥字节码："+Arrays.toString(keyCode));

byte[] finallyCode = new byte[strCode.length];

for(int i=0;istr.length();i++){

finallyCode[i] = (byte) (strCode[i] ^ keyCode[i]);

}

System.out.println("加密后的字节码："+Arrays.toString(finallyCode));

System.out.println("加密后的字符串："+new String(finallyCode));

//============解密

for(int i=0;istr.length();i++){

finallyCode[i] = (byte) (finallyCode[i] ^ keyCode[i]);

}

System.out.println("解密后的字节码："+Arrays.toString(finallyCode));

System.out.println("解密后的字符串："+new String(finallyCode));

}

}

JAVA简单文件加密 求JAVA源代码

md5加密：

package com.ncs.pki.util;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

public class MD5Test {

private static MessageDigest digest = null;

public synchronized static final String hash(String data) {

if (digest == null) {

try {

digest = MessageDigest.getInstance("MD5");

} catch (NoSuchAlgorithmException nsae) {

System.err.println(

"Failed to load the MD5 MessageDigest. "

+ "Jive will be unable to function normally.");

nsae.printStackTrace();

}

}

// Now, compute hash.

digest.update(data.getBytes());

return encodeHex(digest.digest());

}

public static final String encodeHex(byte[] bytes) {

StringBuffer buf = new StringBuffer(bytes.length * 2);

int i;

for (i = 0; i bytes.length; i++) {

if (((int) bytes[i] 0xff) 0x10) {

buf.append("0");

}

buf.append(Long.toString((int) bytes[i] 0xff, 16));

}

return buf.toString();

}

public static String test(){

return null;

}

/**

* @param args

*/

public static void main(String[] args) {

// TODO Auto-generated method stub

System.out.println(MD5Test.hash("123456"));

}

}

3des加密：

package com.ncs.pki.util;

import java.security.Key;

import java.security.SecureRandom;

import javax.crypto.Cipher;

import javax.crypto.KeyGenerator;

import sun.misc.BASE64Decoder;

import sun.misc.BASE64Encoder;

public class DesEncrypt {

/**

*

* 使用DES加密与解密,可对byte[],String类型进行加密与解密 密文可使用String,byte[]存储.

*

* 方法: void getKey(String strKey)从strKey的字条生成一个Key

*

* String getEncString(String strMing)对strMing进行加密,返回String密文 String

* getDesString(String strMi)对strMin进行解密,返回String明文

*

*byte[] getEncCode(byte[] byteS)byte[]型的加密 byte[] getDesCode(byte[]

* byteD)byte[]型的解密

*/

Key key;

/**

* 根据参数生成KEY

*

* @param strKey

*/

public void getKey(String strKey) {

try {

KeyGenerator _generator = KeyGenerator.getInstance("DES");

_generator.init(new SecureRandom(strKey.getBytes()));

this.key = _generator.generateKey();

_generator = null;

} catch (Exception e) {

e.printStackTrace();

}

}

/**

* 加密String明文输入,String密文输出

*

* @param strMing

* @return

*/

public String getEncString(String strMing) {

byte[] byteMi = null;

byte[] byteMing = null;

String strMi = "";

BASE64Encoder base64en = new BASE64Encoder();

try {

byteMing = strMing.getBytes("UTF8");

byteMi = this.getEncCode(byteMing);

strMi = base64en.encode(byteMi);

} catch (Exception e) {

e.printStackTrace();

} finally {

base64en = null;

byteMing = null;

byteMi = null;

}

return strMi;

}

/**

* 解密 以String密文输入,String明文输出

*

* @param strMi

* @return

*/

public String getDesString(String strMi) {

BASE64Decoder base64De = new BASE64Decoder();

byte[] byteMing = null;

byte[] byteMi = null;

String strMing = "";

try {

byteMi = base64De.decodeBuffer(strMi);

byteMing = this.getDesCode(byteMi);

strMing = new String(byteMing, "UTF8");

} catch (Exception e) {

e.printStackTrace();

} finally {

base64De = null;

byteMing = null;

byteMi = null;

}

return strMing;

}

/**

* 加密以byte[]明文输入,byte[]密文输出

*

* @param byteS

* @return

*/

private byte[] getEncCode(byte[] byteS) {

byte[] byteFina = null;

Cipher cipher;

try {

cipher = Cipher.getInstance("DES");

cipher.init(Cipher.ENCRYPT_MODE, key);

byteFina = cipher.doFinal(byteS);

} catch (Exception e) {

e.printStackTrace();

} finally {

cipher = null;

}

return byteFina;

}

/**

* 解密以byte[]密文输入,以byte[]明文输出

*

* @param byteD

* @return

*/

private byte[] getDesCode(byte[] byteD) {

Cipher cipher;

byte[] byteFina = null;

try {

cipher = Cipher.getInstance("DES");

cipher.init(Cipher.DECRYPT_MODE, key);

byteFina = cipher.doFinal(byteD);

} catch (Exception e) {

e.printStackTrace();

} finally {

cipher = null;

}

return byteFina;

}

public static void main(String[] args) {

System.out.println("des demo");

DesEncrypt des = new DesEncrypt();// 实例化一个对像

des.getKey("MYKEY");// 生成密匙

System.out.println("key=MYKEY");

String strEnc = des.getEncString("111111");// 加密字符串,返回String的密文

System.out.println("密文=" + strEnc);

String strDes = des.getDesString(strEnc);// 把String 类型的密文解密

System.out.println("明文=" + strDes);

}

}

java用io怎么对文件进行加密？代码！！

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

import java.io.*;

import java.security.*;

import javax.crypto.*;

import javax.crypto.spec.*;

/**

文件名：FileEncrypter.java

JDK：1.40以上

说明：文件加密

加密方法：三重DES加密

加密过程：对选中的文件加密后在同文件夹下生成一个增加了".tdes"

扩展名的加密文件

解密过程：对选中的加密文件（必须有".tdes"扩展名）进行解密

*/

public class FileEncrypter extends JFrame{

public static final int WIDTH = 550;

public static final int HEIGHT = 200;

public static void main(String args[]) {

FileEncrypter fe = new FileEncrypter();

fe.show();

}

FileEncrypter(){

this.setSize(WIDTH,HEIGHT);

this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

this.setResizable(false);

Toolkit tk = Toolkit.getDefaultToolkit();

Dimension screenSize = tk.getScreenSize();

this.setLocation((screenSize.width - WIDTH)/2,

(screenSize.height - HEIGHT)/2);

this.setTitle("文件加密器(TriDES)");

Container c = this.getContentPane();

c.setLayout( new FlowLayout());

final FilePanel fp = new FilePanel("文件选择");

c.add(fp);

final KeyPanel pp = new KeyPanel("密码");

c.add(pp);

JButton jbE = new JButton("加密");

c.add(jbE);

jbE.addActionListener(new ActionListener(){

public void actionPerformed(ActionEvent event){

File file = new File(fp.getFileName());

if (file.exists())

encrypt(file.getAbsoluteFile(),pp.getKey());

else

JOptionPane.showMessageDialog(

null,"请选择文件！","提示",JOptionPane.OK_OPTION);

}

});

JButton jbD = new JButton("解密");

c.add(jbD);

jbD.addActionListener(new ActionListener(){

public void actionPerformed(ActionEvent event){

File file = new File(fp.getFileName());

if (file.exists())

decrypt(file.getAbsoluteFile(),pp.getKey());

else

JOptionPane.showMessageDialog(

null,"请选择文件！","提示",JOptionPane.OK_OPTION);

}

});

}

/**

加密函数

输入：

要加密的文件，密码（由0-F组成，共48个字符，表示3个8位的密码）如：

AD67EA2F3BE6E5ADD368DFE03120B5DF92A8FD8FEC2F0746

其中：

AD67EA2F3BE6E5AD DES密码一

D368DFE03120B5DF DES密码二

92A8FD8FEC2F0746 DES密码三

输出：

对输入的文件加密后，保存到同一文件夹下增加了".tdes"扩展名的文件中。

*/

private void encrypt(File fileIn,String sKey){

try{

if(sKey.length() == 48){

byte[] bytK1 = getKeyByStr(sKey.substring(0,16));

byte[] bytK2 = getKeyByStr(sKey.substring(16,32));

byte[] bytK3 = getKeyByStr(sKey.substring(32,48));

FileInputStream fis = new FileInputStream(fileIn);

byte[] bytIn = new byte[(int)fileIn.length()];

for(int i = 0;iFILEIN.LENGTH();I++){

bytIn[i] = (byte)fis.read();

}

//加密

byte[] bytOut = encryptByDES(encryptByDES(

encryptByDES(bytIn,bytK1),bytK2),bytK3);

String fileOut = fileIn.getPath() + ".tdes";

FileOutputStream fos = new FileOutputStream(fileOut);

for(int i = 0;iBYTOUT.LENGTH;I++){

fos.write((int)bytOut[i]);

}

fos.close();

JOptionPane.showMessageDialog(

this,"加密成功！","提示",JOptionPane.OK_OPTION);

}else

JOptionPane.showMessageDialog(

this,"密码长度必须等于48！","错误信息",JOptionPane.ERROR_MESSAGE);

}catch(Exception e){

e.printStackTrace();

}

}

/**

解密函数

输入：

要解密的文件，密码（由0-F组成，共48个字符，表示3个8位的密码）如：

AD67EA2F3BE6E5ADD368DFE03120B5DF92A8FD8FEC2F0746

其中：

AD67EA2F3BE6E5AD DES密码一

D368DFE03120B5DF DES密码二

92A8FD8FEC2F0746 DES密码三

输出：

对输入的文件解密后，保存到用户指定的文件中。

*/

private void decrypt(File fileIn,String sKey){

try{

if(sKey.length() == 48){

String strPath = fileIn.getPath();

if(strPath.substring(strPath.length()-5).toLowerCase().equals(".tdes"))

strPath = strPath.substring(0,strPath.length()-5);

else{

JOptionPane.showMessageDialog(

this,"不是合法的加密文件！","提示",JOptionPane.OK_OPTION);

return;

}

JFileChooser chooser = new JFileChooser();

chooser.setCurrentDirectory(new File("."));

chooser.setSelectedFile(new File(strPath));

//用户指定要保存的文件

int ret = chooser.showSaveDialog(this);

if(ret==JFileChooser.APPROVE_OPTION){

byte[] bytK1 = getKeyByStr(sKey.substring(0,16));

byte[] bytK2 = getKeyByStr(sKey.substring(16,32));

byte[] bytK3 = getKeyByStr(sKey.substring(32,48));

FileInputStream fis = new FileInputStream(fileIn);

byte[] bytIn = new byte[(int)fileIn.length()];

for(int i = 0;iFILEIN.LENGTH();I++){

bytIn[i] = (byte)fis.read();

}

//解密

byte[] bytOut = decryptByDES(decryptByDES(

decryptByDES(bytIn,bytK3),bytK2),bytK1);

File fileOut = chooser.getSelectedFile();

fileOut.createNewFile();

FileOutputStream fos = new FileOutputStream(fileOut);

for(int i = 0;iBYTOUT.LENGTH;I++){

fos.write((int)bytOut[i]);

}

fos.close();

JOptionPane.showMessageDialog(

this,"解密成功！","提示",JOptionPane.OK_OPTION);

}

}else

JOptionPane.showMessageDialog(

this,"密码长度必须等于48！","错误信息",JOptionPane.ERROR_MESSAGE);

}catch(Exception e){

JOptionPane.showMessageDialog(

this,"解密失败，请核对密码！","提示",JOptionPane.OK_OPTION);

}

}

/**

用DES方法加密输入的字节

bytKey需为8字节长，是加密的密码

*/

private byte[] encryptByDES(byte[] bytP,byte[] bytKey) throws Exception{

DESKeySpec desKS = new DESKeySpec(bytKey);

SecretKeyFactory skf = SecretKeyFactory.getInstance("DES");

SecretKey sk = skf.generateSecret(desKS);

Cipher cip = Cipher.getInstance("DES");

cip.init(Cipher.ENCRYPT_MODE,sk);

return cip.doFinal(bytP);

}

/**

用DES方法解密输入的字节

bytKey需为8字节长，是解密的密码

*/

private byte[] decryptByDES(byte[] bytE,byte[] bytKey) throws Exception{

DESKeySpec desKS = new DESKeySpec(bytKey);

SecretKeyFactory skf = SecretKeyFactory.getInstance("DES");

SecretKey sk = skf.generateSecret(desKS);

Cipher cip = Cipher.getInstance("DES");

cip.init(Cipher.DECRYPT_MODE,sk);

return cip.doFinal(bytE);

}

/**

输入密码的字符形式，返回字节数组形式。

如输入字符串：AD67EA2F3BE6E5AD

返回字节数组：{173,103,234,47,59,230,229,173}

*/

private byte[] getKeyByStr(String str){

byte[] bRet = new byte[str.length()/2];

for(int i=0;iSTR.LENGTH()

Integer itg =

new Integer(16*getChrInt(str.charAt(2*i)) + getChrInt(str.charAt(2*i+1)));

bRet[i] = itg.byteValue();

}

return bRet;

}

/**

计算一个16进制字符的10进制值

输入：0-F

*/

private int getChrInt(char chr){

int iRet=0;

if(chr=="0".charAt(0)) iRet = 0;

if(chr=="1".charAt(0)) iRet = 1;

if(chr=="2".charAt(0)) iRet = 2;

if(chr=="3".charAt(0)) iRet = 3;

if(chr=="4".charAt(0)) iRet = 4;

if(chr=="5".charAt(0)) iRet = 5;

if(chr=="6".charAt(0)) iRet = 6;

if(chr=="7".charAt(0)) iRet = 7;

if(chr=="8".charAt(0)) iRet = 8;

if(chr=="9".charAt(0)) iRet = 9;

if(chr=="A".charAt(0)) iRet = 10;

if(chr=="B".charAt(0)) iRet = 11;

if(chr=="C".charAt(0)) iRet = 12;

if(chr=="D".charAt(0)) iRet = 13;

if(chr=="E".charAt(0)) iRet = 14;

if(chr=="F".charAt(0)) iRet = 15;

return iRet;

}

}

/**

文件选择组件。

*/

class FilePanel extends JPanel{

FilePanel(String str){

JLabel label = new JLabel(str);

JTextField fileText = new JTextField(35);

JButton chooseButton = new JButton("浏览...");

this.add(label);

this.add(fileText);

this.add(chooseButton);

clickAction ca = new clickAction(this);

chooseButton.addActionListener(ca);

}

public String getFileName(){

JTextField jtf = (JTextField)this.getComponent(1);

return jtf.getText();

}

private class clickAction implements ActionListener{

clickAction(Component c){

cmpt = c;

}

public void actionPerformed(ActionEvent event){

JFileChooser chooser = new JFileChooser();

chooser.setCurrentDirectory(new File("."));

int ret = chooser.showOpenDialog(cmpt);

if(ret==JFileChooser.APPROVE_OPTION){

JPanel jp = (JPanel)cmpt;

JTextField jtf = (JTextField)jp.getComponent(1);

jtf.setText(chooser.getSelectedFile().getPath());

}

}

private Component cmpt;

}

}

/**

密码生成组件。

*/

class KeyPanel extends JPanel{

KeyPanel(String str){

JLabel label = new JLabel(str);

JTextField fileText = new JTextField(35);

JButton chooseButton = new JButton("随机产生");

this.add(label);

this.add(fileText);

this.add(chooseButton);

clickAction ca = new clickAction(this);

chooseButton.addActionListener(ca);

}

//返回生成的密码（48个字符长度）

public String getKey(){

JTextField jtf = (JTextField)this.getComponent(1);

return jtf.getText();

}

private class clickAction implements ActionListener{

clickAction(Component c){

cmpt = c;

}

public void actionPerformed(ActionEvent event){

try{

KeyGenerator kg = KeyGenerator.getInstance("DES");

kg.init(56);

Key ke = kg.generateKey();

byte[] bytK1 = ke.getEncoded();

ke = kg.generateKey();

byte[] bytK2 = ke.getEncoded();

ke = kg.generateKey();

byte[] bytK3 = ke.getEncoded();

JPanel jp = (JPanel)cmpt;

JTextField jtf = (JTextField)jp.getComponent(1);

jtf.setText(getByteStr(bytK1)+getByteStr(bytK2)+getByteStr(bytK3));

}catch(Exception e){

e.printStackTrace();

}

}

private String getByteStr(byte[] byt){

String strRet = "";

for(int i=0;iBYT.LENGTH;I++){

//System.out.println(byt[i]);

strRet += getHexValue((byt[i]240)/16);

strRet += getHexValue(byt[i]15);

}

return strRet;

}

private String getHexValue(int s){

String sRet=null;

switch (s){

case 0: sRet = "0";break;

case 1: sRet = "1";break;

case 2: sRet = "2";break;

case 3: sRet = "3";break;

case 4: sRet = "4";break;

case 5: sRet = "5";break;

case 6: sRet = "6";break;

case 7: sRet = "7";break;

case 8: sRet = "8";break;

case 9: sRet = "9";break;

case 10: sRet = "A";break;

case 11: sRet = "B";break;

case 12: sRet = "C";break;

case 13: sRet = "D";break;

case 14: sRet = "E";break;

case 15: sRet = "F";

}

return sRet;

}

private Component cmpt;

}

}

求java文件加密代码

package com.happy.security.properties;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.InputStream;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.security.Key;

import java.security.NoSuchAlgorithmException;

import java.security.SecureRandom;

import java.security.Security;

import javax.crypto.Cipher;

import javax.crypto.KeyGenerator;

public class DESEncryptUtil {

public static Key createKey() throws NoSuchAlgorithmException {//创建密钥

Security.insertProviderAt(new com.sun.crypto.provider.SunJCE(), 1);

KeyGenerator generator = KeyGenerator.getInstance("DES");

generator.init(new SecureRandom());

Key key = generator.generateKey();

return key;

}

public static Key getKey(InputStream is) {

try {

ObjectInputStream ois = new ObjectInputStream(is);

return (Key) ois.readObject();

} catch (Exception e) {

e.printStackTrace();

throw new RuntimeException(e);

}

}

private static byte[] doEncrypt(Key key, byte[] data) {//对数据进行加密?

try {

Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");

cipher.init(Cipher.ENCRYPT_MODE, key);

byte[] raw = cipher.doFinal(data);

return raw;

} catch (Exception e) {

e.printStackTrace();

throw new RuntimeException(e);

}

}

public static InputStream doDecrypt(Key key, InputStream in) {//对数据进行解密?

try {

Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");

cipher.init(Cipher.DECRYPT_MODE, key);

ByteArrayOutputStream bout = new ByteArrayOutputStream();

byte[] tmpbuf = new byte[1024];

int count = 0;

while ((count = in.read(tmpbuf)) != -1) {

bout.write(tmpbuf, 0, count);

tmpbuf = new byte[1024];

}

in.close();

byte[] orgData = bout.toByteArray();

byte[] raw = cipher.doFinal(orgData);

ByteArrayInputStream bin = new ByteArrayInputStream(raw);

return bin;

} catch (Exception e){

e.printStackTrace();

throw new RuntimeException(e);

}

}

public static void main(String[] args) throws Exception{

System.out.println("===================");

if (args.length == 2 args[0].equals("key")){

Key key = DESEncryptUtil.createKey();

ObjectOutputStream oos = new ObjectOutputStream(

new FileOutputStream(args[1]));

oos.writeObject(key);

oos.close();

System.out.println("成功生成密钥文件");

} else if (args.length == 3 args[0].equals("encrypt")){

File file = new File(args[1]);

FileInputStream in = new FileInputStream(file);

ByteArrayOutputStream bout = new ByteArrayOutputStream();

byte[] tmpbuf = new byte[1024];

int count = 0;

while ((count = in.read(tmpbuf)) != -1){

bout.write(tmpbuf, 0, count);

tmpbuf = new byte[1024];

}

in.close();

byte[] orgData = bout.toByteArray();

Key key = getKey(new FileInputStream(args[2]));

byte[] raw = DESEncryptUtil.doEncrypt(key, orgData);

file = new File(file.getParent() + "\\en_" + file.getName());

FileOutputStream out = new FileOutputStream(file);

out.write(raw);

out.close();

System.out.println("成功加密，加密文件位:"+file.getAbsolutePath());

} else if (args.length == 3 args[0].equals("decrypt")){//对文件进行解密

File file = new File(args[1]);

FileInputStream fis = new FileInputStream(file);

Key key = getKey(new FileInputStream(args[2]));

InputStream raw = DESEncryptUtil.doDecrypt(key, fis);

ByteArrayOutputStream bout = new ByteArrayOutputStream();

byte[] tmpbuf = new byte[1024];

int count = 0;

while ((count = raw.read(tmpbuf)) != -1){

bout.write(tmpbuf, 0, count);

tmpbuf = new byte[1024];

}

raw.close();

byte[] orgData = bout.toByteArray();

file = new File(file.getParent() + "\\rs_" + file.getName());

FileOutputStream fos = new FileOutputStream(file);

fos.write(orgData);

System.out.println("成功解密，解密文件位:"+file.getAbsolutePath());

}else if(args.length==1 args[0].equals("-h")) {

System.out.println("\t文件加密解密\n");

System.out.println

用java实现文件加密，帮忙修改下代码

这个应该和你的文件内容有关,你文件里不是数字的,你用nextInt就会出错.

你文件里是下边的内容你试一下

111111

2222

333

444

求java加密源代码（MD5，base64）

import java.security.*;

import javax.crypto.*;

/**

* 本例解释如何利用DES私钥加密算法加解密

*

* @author Devon

* @version 1.0 04/03/10

*/

public class SingleKeyExample {

public static void main(String[] args) {

try {

String algorithm = "DES"; //定义加密算法,可用 DES,DESede,Blowfish

String message = "Hello World. 这是待加密的信息";

// 生成个DES密钥

KeyGenerator keyGenerator = KeyGenerator.getInstance(algorithm);

keyGenerator.init(56); //选择DES算法,密钥长度必须为56位

Key key = keyGenerator.generateKey(); //生成密钥

// 生成Cipher对象

Cipher cipher = Cipher.getInstance("DES");

//用密钥加密明文(message),生成密文(cipherText)

cipher.init(Cipher.ENCRYPT_MODE, key); //操作模式为加密(Cipher.ENCRYPT_MODE),key为密钥

byte[] cipherText = cipher.doFinal(message.getBytes()); //得到加密后的字节数组

System.out.println("加密后的信息: " + new String(cipherText));

//用密钥加密明文(plainText),生成密文(cipherByte)

cipher.init(Cipher.DECRYPT_MODE, key); //操作模式为解密,key为密钥

byte[] sourceText = cipher.doFinal(cipherText); //获得解密后字节数组

System.out.println("解密后的信息: " + new String(sourceText));

} catch (Exception ex) {

ex.printStackTrace();

}

}

}

/**

* @author Devon

*/

import java.security.*;

import java.security.spec.*;

import javax.crypto.*;

public class PairKeyExample {

public static void main(String argv[]) {

try {

String algorithm = "RSA"; //定义加密算法,可用 DES,DESede,Blowfish

String message = "张三，你好，我是李四";

//产生张三的密钥对(keyPairZhang)

KeyPairGenerator keyGeneratorZhang =

KeyPairGenerator.getInstance(algorithm); //指定采用的算法

keyGeneratorZhang.initialize(1024); //指定密钥长度为1024位

KeyPair keyPairZhang = keyGeneratorZhang.generateKeyPair(); //产生密钥对

System.out.println("生成张三的公钥对");

// 张三生成公钥(publicKeyZhang)并发送给李四,这里发送的是公钥的数组字节

byte[] publicKeyZhangEncode = keyPairZhang.getPublic().getEncoded();

//通过网络或磁盘等方式,把公钥编码传送给李四

//李四接收到张三编码后的公钥,将其解码

KeyFactory keyFacoryLi = KeyFactory.getInstance(algorithm); //得到KeyFactory对象

X509EncodedKeySpec x509KeySpec =

new X509EncodedKeySpec(publicKeyZhangEncode); //公钥采用X.509编码

PublicKey publicKeyZhang = keyFacoryLi.generatePublic(x509KeySpec); //将公钥的KeySpec对象转换为公钥

System.out.println("李四成功解码,得到张三的公钥");

//李四用张三的公钥加密信息，并发送给李四

Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding"); //得到Cipher对象

cipher.init(Cipher.ENCRYPT_MODE, publicKeyZhang); //用张三的公钥初始化Cipher对象

byte[] cipherMessage = cipher.doFinal(message.getBytes()); //得到加密信息

System.out.println("加密后信息：" + new String(cipherMessage));

System.out.println("加密完成，发送给李四...");

//张三用自己的私钥解密从李四处收到的信息

cipher.init(Cipher.DECRYPT_MODE, keyPairZhang.getPrivate()); //张三用其私钥初始化Cipher对象

byte[] originalMessage = cipher.doFinal(cipherMessage); //得到解密后信息

System.out.println("张三收到信息，解密后为：" + new String(originalMessage));

} catch (Exception ex) {

ex.printStackTrace();

}

}

}