对称加密与非对称加密理解和非对称加密的java例子

对称加密与非对称加密理解和非对称加密的java例子
1.对称加密：一般小于256 bit的密钥，密钥越大越安全，但是解密和加密时间越长。加密和解密都是用的相同的密钥，快速简单
2.非对称加密：有公钥和私钥，只有私钥才能打开公钥，比如：你向银行请求公钥，银行将公钥发给你，你使用公钥对消息加密，那么只有私钥的持有人--银行才能对你的消息解密。与对称加密不同的是，银行不需要将私钥通过网络发送出去，因此安全性大大提高。但是速度慢

（1） Alice需要在银行的网站做一笔交易，她的浏览器首先生成了一个随机数作为对称密钥。

（2） Alice的浏览器向银行的网站请求公钥。

（3） 银行将公钥发送给Alice。

（4） Alice的浏览器使用银行的公钥将自己的对称密钥加密。

（5） Alice的浏览器将加密后的对称密钥发送给银行。

（6） 银行使用私钥解密得到Alice浏览器的对称密钥。

（7） Alice与银行可以使用对称密钥来对沟通的内容进行加密与解密了。
3.rsa公钥加密私钥解密算法实例
公钥加密不能超过117   私钥解密不能超过128     不过在此代码中已经分段处理了
3.1新建java工程，导入jar包

package com.zl.test3;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.ByteArrayOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

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

public class RSAEncrypt {
/**
* 字节数据转字符串专用集合
*/
private static final char[] HEX_CHAR = { '0', '1', '2', '3', '4', '5', '6',
'7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

/**
* 随机生成密钥对
*/
public static void genKeyPair(String filePath) {
// KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
KeyPairGenerator keyPairGen = null;
try {
keyPairGen = KeyPairGenerator.getInstance("RSA");
} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// 初始化密钥对生成器，密钥大小为96-1024位
keyPairGen.initialize(1024,new SecureRandom());
// 生成一个密钥对，保存在keyPair中
KeyPair keyPair = keyPairGen.generateKeyPair();
// 得到私钥
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
// 得到公钥
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
try {
// 得到公钥字符串
String publicKeyString = Base64.encode(publicKey.getEncoded());
// 得到私钥字符串
String privateKeyString = Base64.encode(privateKey.getEncoded());
// 将密钥对写入到文件
FileWriter pubfw = new FileWriter(filePath + "/publicKey.keystore");
FileWriter prifw = new FileWriter(filePath + "/privateKey.keystore");
BufferedWriter pubbw = new BufferedWriter(pubfw);
BufferedWriter pribw = new BufferedWriter(prifw);
pubbw.write(publicKeyString);
pribw.write(privateKeyString);
pubbw.flush();
pubbw.close();
pubfw.close();
pribw.flush();
pribw.close();
prifw.close();
} catch (Exception e) {
e.printStackTrace();
}
}

/**
* 从文件中输入流中加载公钥
*
* @param in
*            公钥输入流
* @throws Exception
*             加载公钥时产生的异常
*/
public static String loadPublicKeyByFile(String path) throws Exception {
try {
BufferedReader br = new BufferedReader(new FileReader(path
+ "/publicKey.keystore"));
String readLine = null;
StringBuilder sb = new StringBuilder();
while ((readLine = br.readLine()) != null) {
sb.append(readLine);
}
br.close();
return sb.toString();
} catch (IOException e) {
throw new Exception("公钥数据流读取错误");
} catch (NullPointerException e) {
throw new Exception("公钥输入流为空");
}
}

/**
* 从字符串中加载公钥
*
* @param publicKeyStr
*            公钥数据字符串
* @throws Exception
*             加载公钥时产生的异常
*/
public static RSAPublicKey loadPublicKeyByStr(String publicKeyStr)
throws Exception {
try {
byte[] buffer = Base64.decode(publicKeyStr);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
return (RSAPublicKey) keyFactory.generatePublic(keySpec);
} catch (NoSuchAlgo
112fa
rithmException e) {
throw new Exception("无此算法");
} catch (InvalidKeySpecException e) {
throw new Exception("公钥非法");
} catch (NullPointerException e) {
throw new Exception("公钥数据为空");
}
}

/**
* 从文件中加载私钥
*
* @param keyFileName
*            私钥文件名
* @return 是否成功
* @throws Exception
*/
public static String loadPrivateKeyByFile(String path) throws Exception {
try {
BufferedReader br = new BufferedReader(new FileReader(path
+ "/privateKey.keystore"));
String readLine = null;
StringBuilder sb = new StringBuilder();
while ((readLine = br.readLine()) != null) {
sb.append(readLine);
}
br.close();
return sb.toString();
} catch (IOException e) {
throw new Exception("私钥数据读取错误");
} catch (NullPointerException e) {
throw new Exception("私钥输入流为空");
}
}

public static RSAPrivateKey loadPrivateKeyByStr(String privateKeyStr)
throws Exception {
try {
byte[] buffer = Base64.decode(privateKeyStr);
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
} catch (NoSuchAlgorithmException e) {
throw new Exception("无此算法");
} catch (InvalidKeySpecException e) {
throw new Exception("私钥非法");
} catch (NullPointerException e) {
throw new Exception("私钥数据为空");
}
}

/**
* 公钥加密过程
*
* @param publicKey
*            公钥
* @param plainTextData
*            明文数据
* @return
* @throws Exception
*             加密过程中的异常信息
*/
public static byte[] encrypt(RSAPublicKey publicKey, byte[] data)
throws Exception {
if (publicKey == null) {
throw new Exception("加密公钥为空, 请设置");
}
Cipher cipher = null;
try {
// 使用默认RSA
cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
int inputLen = data.length;
ByteArrayOutputStream out = new ByteArrayOutputStream();
int offSet = 0;
byte[] cache;
int i = 0;
// 对数据分段加密
while (inputLen - offSet > 0) {
if (inputLen - offSet > 117) {
cache = cipher.doFinal(data, offSet, 117);
} else {
cache = cipher.doFinal(data, offSet, inputLen - offSet);
}
out.write(cache, 0, cache.length);
i++;
offSet = i * 117;
}
byte[] encryptedData = out.toByteArray();
out.close();
return encryptedData;
//            byte[] output = cipher.doFinal(data);
//            return output;
} catch (NoSuchAlgorithmException e) {
throw new Exception("无此加密算法");
} catch (NoSuchPaddingException e) {
e.printStackTrace();
return null;
} catch (InvalidKeyException e) {
throw new Exception("加密公钥非法,请检查");
} catch (IllegalBlockSizeException e) {
throw new Exception("明文长度非法");
} catch (BadPaddingException e) {
throw new Exception("明文数据已损坏");
}
}

/**
* 私钥加密过程
*
* @param privateKey
*            私钥
* @param plainTextData
*            明文数据
* @return
* @throws Exception
*             加密过程中的异常信息
*/
public static byte[] encrypt(RSAPrivateKey privateKey, byte[] plainTextData)
throws Exception {
if (privateKey == null) {
throw new Exception("加密私钥为空, 请设置");
}
Cipher cipher = null;
try {
// 使用默认RSA
cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
// 加密时超过117字节就报错。为此采用分段加密的办法来加密
byte[] output = cipher.doFinal(plainTextData);
return output;
} catch (NoSuchAlgorithmException e) {
throw new Exception("无此加密算法");
} catch (NoSuchPaddingException e) {
e.printStackTrace();
return null;
} catch (InvalidKeyException e) {
throw new Exception("加密私钥非法,请检查");
} catch (IllegalBlockSizeException e) {
throw new Exception("明文长度非法");
} catch (BadPaddingException e) {
throw new Exception("明文数据已损坏");
}
}

/**
* 私钥解密过程
*
* @param privateKey
*            私钥
* @param cipherData
*            密文数据
* @return 明文
* @throws Exception
*             解密过程中的异常信息
*/
public static byte[] decrypt(RSAPrivateKey privateKey, byte[] encryptedData)
throws Exception {
if (privateKey == null) {
throw new Exception("解密私钥为空, 请设置");
}
Cipher cipher = null;
try {
// 使用默认RSA
cipher = Cipher.getInstance("RSA");
// cipher= Cipher.getInstance("RSA", new BouncyCastleProvider());
cipher.init(Cipher.DECRYPT_MODE, privateKey);
int inputLen = encryptedData.length;
ByteArrayOutputStream out = new ByteArrayOutputStream();
int offSet = 0;
byte[] cache;
int i = 0;
// 对数据分段解密
while (inputLen - offSet > 0) {
if (inputLen - offSet > 128) {
cache = cipher.doFinal(encryptedData, offSet, 128);
} else {
cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
}
out.write(cache, 0, cache.length);
i++;
offSet = i * 128;
}
byte[] decryptedData = out.toByteArray();
out.close();
return decryptedData;
//            byte[] output = cipher.doFinal(encryptedData);
//            return output;
} catch (NoSuchAlgorithmException e) {
throw new Exception("无此解密算法");
} catch (NoSuchPaddingException e) {
e.printStackTrace();
return null;
} catch (InvalidKeyException e) {
throw new Exception("解密私钥非法,请检查");
} catch (IllegalBlockSizeException e) {
throw new Exception("密文长度非法");
} catch (BadPaddingException e) {
throw new Exception("密文数据已损坏");
}
}

/**
* 公钥解密过程
*
* @param publicKey
*            公钥
* @param cipherData
*            密文数据
* @return 明文
* @throws Exception
*             解密过程中的异常信息
*/
public static byte[] decrypt(RSAPublicKey publicKey, byte[] cipherData)
throws Exception {
if (publicKey == null) {
throw new Exception("解密公钥为空, 请设置");
}
Cipher cipher = null;
try {
// 使用默认RSA
cipher = Cipher.getInstance("RSA");
// cipher= Cipher.getInstance("RSA", new BouncyCastleProvider());
cipher.init(Cipher.DECRYPT_MODE, publicKey);
byte[] output = cipher.doFinal(cipherData);
return output;
} catch (NoSuchAlgorithmException e) {
throw new Exception("无此解密算法");
} catch (NoSuchPaddingException e) {
e.printStackTrace();
return null;
} catch (InvalidKeyException e) {
throw new Exception("解密公钥非法,请检查");
} catch (IllegalBlockSizeException e) {
throw new Exception("密文长度非法");
} catch (BadPaddingException e) {
throw new Exception("密文数据已损坏");
}
}

/**
* 字节数据转十六进制字符串
*
* @param data
*            输入数据
* @return 十六进制内容
*/
public static String byteArrayToString(byte[] data) {
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i < data.length; i++) {
// 取出字节的高四位 作为索引得到相应的十六进制标识符 注意无符号右移
stringBuilder.append(HEX_CHAR[(data[i] & 0xf0) >>> 4]);
// 取出字节的低四位 作为索引得到相应的十六进制标识符
stringBuilder.append(HEX_CHAR[(data[i] & 0x0f)]);
if (i < data.length - 1) {
stringBuilder.append(' ');
}
}
return stringBuilder.toString();
}
}

3.2

package com.zl.test3;
/**
*
* @author zenglong
*
* @Description: Base64算法
*
*/
public final class Base64 {

static private final int     BASELENGTH           = 128;
static private final int     LOOKUPLENGTH         = 64;
static private final int     TWENTYFOURBITGROUP   = 24;
static private final int     EIGHTBIT             = 8;
static private final int     SIXTEENBIT           = 16;
static private final int     FOURBYTE             = 4;
static private final int     SIGN                 = -128;
static private final char    PAD                  = '=';
static private final boolean fDebug               = false;
static final private byte[]  base64Alphabet       = new byte[BASELENGTH];
static final private char[]  lookUpBase64Alphabet = new char[LOOKUPLENGTH];

static {
for (int i = 0; i < BASELENGTH; ++i) {
base64Alphabet[i] = -1;
}
for (int i = 'Z'; i >= 'A'; i--) {
base64Alphabet[i] = (byte) (i - 'A');
}
for (int i = 'z'; i >= 'a'; i--) {
base64Alphabet[i] = (byte) (i - 'a' + 26);
}

for (int i = '9'; i >= '0'; i--) {
base64Alphabet[i] = (byte) (i - '0' + 52);
}

base64Alphabet['+'] = 62;
base64Alphabet['/'] = 63;

for (int i = 0; i <= 25; i++) {
lookUpBase64Alphabet[i] = (char) ('A' + i);
}

for (int i = 26, j = 0; i <= 51; i++, j++) {
lookUpBase64Alphabet[i] = (char) ('a' + j);
}

for (int i = 52, j = 0; i <= 61; i++, j++) {
lookUpBase64Alphabet[i] = (char) ('0' + j);
}
lookUpBase64Alphabet[62] = (char) '+';
lookUpBase64Alphabet[63] = (char) '/';

}

private static boolean isWhiteSpace(char octect) {
return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
}

private static boolean isPad(char octect) {
return (octect == PAD);
}

private static boolean isData(char octect) {
return (octect < BASELENGTH && base64Alphabet[octect] != -1);
}

/**
* Encodes hex octects into Base64
*
* @param binaryData Array containing binaryData
* @return Encoded Base64 array
*/
public static String encode(byte[] binaryData) {

if (binaryData == null) {
return null;
}

int lengthDataBits = binaryData.length * EIGHTBIT;
if (lengthDataBits == 0) {
return "";
}

int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
int numberQuartet = fewerThan24bits != 0 ? numberTriplets + 1 : numberTriplets;
char encodedData[] = null;

encodedData = new char[numberQuartet * 4];

byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;

int encodedIndex = 0;
int dataIndex = 0;
if (fDebug) {
System.out.println("number of triplets = " + numberTriplets);
}

for (int i = 0; i < numberTriplets; i++) {
b1 = binaryData[dataIndex++];
b2 = binaryData[dataIndex++];
b3 = binaryData[dataIndex++];

if (fDebug) {
System.out.println("b1= " + b1 + ", b2= " + b2 + ", b3= " + b3);
}

l = (byte) (b2 & 0x0f);
k = (byte) (b1 & 0x03);

byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6) : (byte) ((b3) >> 6 ^ 0xfc);

if (fDebug) {
System.out.println("val2 = " + val2);
System.out.println("k4   = " + (k << 4));
System.out.println("vak  = " + (val2 | (k << 4)));
}

encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
encodedData[encodedIndex++] = lookUpBase64Alphabet[(l << 2) | val3];
encodedData[encodedIndex++] = lookUpBase64Alphabet[b3 & 0x3f];
}

// form integral number of 6-bit groups
if (fewerThan24bits == EIGHTBIT) {
b1 = binaryData[dataIndex];
k = (byte) (b1 & 0x03);
if (fDebug) {
System.out.println("b1=" + b1);
System.out.println("b1<<2 = " + (b1 >> 2));
}
byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
encodedData[encodedIndex++] = lookUpBase64Alphabet[k << 4];
encodedData[encodedIndex++] = PAD;
encodedData[encodedIndex++] = PAD;
} else if (fewerThan24bits == SIXTEENBIT) {
b1 = binaryData[dataIndex];
b2 = binaryData[dataIndex + 1];
l = (byte) (b2 & 0x0f);
k = (byte) (b1 & 0x03);

byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);

encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
encodedData[encodedIndex++] = lookUpBase64Alphabet[l << 2];
encodedData[encodedIndex++] = PAD;
}

return new String(encodedData);
}

/**
* Decodes Base64 data into octects
*
* @param encoded string containing Base64 data
* @return Array containind decoded data.
*/
public static byte[] decode(String encoded) {

if (encoded == null) {
return null;
}

char[] base64Data = encoded.toCharArray();
// remove white spaces
int len = removeWhiteSpace(base64Data);

if (len % FOURBYTE != 0) {
return null;//should be divisible by four
}

int numberQuadruple = (len / FOURBYTE);

if (numberQuadruple == 0) {
return new byte[0];
}

byte decodedData[] = null;
byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;
char d1 = 0, d2 = 0, d3 = 0, d4 = 0;

int i = 0;
int encodedIndex = 0;
int dataIndex = 0;
decodedData = new byte[(numberQuadruple) * 3];

for (; i < numberQuadruple - 1; i++) {

if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))
|| !isData((d3 = base64Data[dataIndex++]))
|| !isData((d4 = base64Data[dataIndex++]))) {
return null;
}//if found "no data" just return null

b1 = base64Alphabet[d1];
b2 = base64Alphabet[d2];
b3 = base64Alphabet[d3];
b4 = base64Alphabet[d4];

decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
}

if (!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))) {
return null;//if found "no data" just return null
}

b1 = base64Alphabet[d1];
b2 = base64Alphabet[d2];

d3 = base64Data[dataIndex++];
d4 = base64Data[dataIndex++];
if (!isData((d3)) || !isData((d4))) {//Check if they are PAD characters
if (isPad(d3) && isPad(d4)) {
if ((b2 & 0xf) != 0)//last 4 bits should be zero
{
return null;
}
byte[] tmp = new byte[i * 3 + 1];
System.arraycopy(decodedData, 0, tmp, 0, i * 3);
tmp[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
return tmp;
} else if (!isPad(d3) && isPad(d4)) {
b3 = base64Alphabet[d3];
if ((b3 & 0x3) != 0)//last 2 bits should be zero
{
return null;
}
byte[] tmp = new byte[i * 3 + 2];
System.arraycopy(decodedData, 0, tmp, 0, i * 3);
tmp[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
tmp[encodedIndex] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
return tmp;
} else {
return null;
}
} else { //No PAD e.g 3cQl
b3 = base64Alphabet[d3];
b4 = base64Alphabet[d4];
decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);

}

return decodedData;
}

/**
* remove WhiteSpace from MIME containing encoded Base64 data.
*
* @param data  the byte array of base64 data (with WS)
* @return      the new length
*/
private static int removeWhiteSpace(char[] data) {
if (data == null) {
return 0;
}

// count characters that's not whitespace
int newSize = 0;
int len = data.length;
for (int i = 0; i < len; i++) {
if (!isWhiteSpace(data[i])) {
data[newSize++] = data[i];
}
}
return newSize;
}
}

package com.zl.test3;

public class MainTest {

public static void main(String[] args) throws Exception {
String filepath="F:/javaee/bgyworkspace/Security/doc";

System.out.println("--------------公钥加密私钥解密过程-------------------");
//        String plainText="ihep_公钥加密私钥解密";
String  json="{"
+ "\"bgyprogressuuid\": \"aabc891fc62f41728497da2904294e16\","
+ "\"bgysupplier\": \"供应商名称3\","
+ " \"bgyitemname\": \"项目公司名称3\","
+ "\"bgyitemcode\": \"0003\","
+ "\"bgyarea\": \"佛山区域3\","
+ "\"bgycontractname\": \"合同名称\","
+ "\"bgycontractno\": \"合同编号003\","
+ "\"bgypayamount\": 888.989,"
+ "\"bgysupplierbank\": \"供应商开户行：中国银行\","
+ "\"bgysupplieraccount\": \"供应商账号：88888989989\","
+ "\"bgysupplieraccountname\": \"收方户名：佛山碧桂园\","
+ "\"bgypaystatus\": false,"
+ "\"dr\": 0}"
+"{"
+ "\"bgyprogressuuid\": \"aabc891fc62f41728497da2904294e15\","
+ "\"bgysupplier\": \"供应商名称3\","
+ " \"bgyitemname\": \"项目公司名称3\","
+ "\"bgyitemcode\": \"0003\","
+ "\"bgyarea\": \"佛山区域3\","
+ "\"bgycontractname\": \"合同名称\","
+ "\"bgycontractno\": \"合同编号003\","
+ "\"bgypayamount\": 888.989,"
+ "\"bgysupplierbank\": \"供应商开户行：中国银行\","
+ "\"bgysupplieraccount\": \"供应商账号：88888989989\","
+ "\"bgysupplieraccountname\": \"收方户名：佛山碧桂园\","
+ "\"bgypaystatus\": false,"
+ "\"dr\": 0}";
//公钥加密过程
byte[] cipherData=RSAEncrypt.encrypt(RSAEncrypt.loadPublicKeyByStr(RSAEncrypt.loadPublicKeyByFile(filepath)),json.getBytes());
String cipher=Base64.encode(cipherData);
//私钥解密过程
byte[] res=RSAEncrypt.decrypt(RSAEncrypt.loadPrivateKeyByStr(RSAEncrypt.loadPrivateKeyByFile(filepath)), Base64.decode(cipher));
String restr=new String(res);
System.out.println("原文："+json);
System.out.println("加密："+cipher);
System.out.println("解密："+restr);
System.out.println();

}
}

4.源代码下载地址：其中有3个实例，都是可以运行的，点击打开链接
http://download.csdn.net/detail/qq_31968809/9777763