Java加密与解密学习记录05-非对称加密算法

概述

1、与对称加密算法的主要差别在于，加密和解密的密钥不相同，一个公开（公钥），一个保密（私钥）。主要解决了对称加密算法密钥分配管理的问题，提高了算法安全性。

2、非对称加密算法的加密、解密的效率比较低。在算法设计上，非对称加密算法对待加密的数据长度有着苛刻的要求。例如RSA算法要求待加密的数据不得大于53个字节。

3、非对称加密算法主要用于 交换对称加密算法的密钥，而非数据交换

4、java6提供实现了DH和RSA两种算法。Bouncy Castle提供了E1Gamal算法支持。除了上述三种算法还有一个ECC算法，目前没有相关的开源组件提供支持

模型分析

我们还是以甲乙双方发送数据为模型进行分析

1、甲方（消息发送方，下同）构建密钥对（公钥+私钥），甲方公布公钥给乙方（消息接收方，下同）

2、乙方以甲方发送过来的公钥作为参数构造密钥对（公钥+私钥），将构造出来的公钥公布给甲方

3、甲方用“甲方的私钥+乙方的公钥”构造本地密钥

4、乙方用“乙方的私钥+甲方的公钥”构造本地的密钥

5、这个时候，甲乙两方本地新构造出来的密钥应该一样。然后就可以使用AES这类对称加密算法结合密钥进行数据的安全传送了。传送过程参考AES的相关算法

密钥交互加密算法-DH

运行代码如果出现 java.security.InvalidKeyException: Illegal key size or default parameters异常信息

原因如下：

当密钥大于128时，代码会抛出Java.security.InvalidKeyException: Illegal key size or default parameters

Illegal key size or default parameters是指密钥长度是受限制的，java运行时环境读到的是受限的policy文件。文件位于${java_home}/jre/lib/security

这种限制是因为美国对软件出口的控制。

解决方案：

需要下载Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files.

下载包的readme.txt 有安装说明。就是替换${java_home}/jre/lib/security/ 下面的local_policy.jar和US_export_policy.jar

下载地址 ： jdk官网 找到对应jdk版本 页面会有 Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files for JDK/JRE 这样的字样 对应的链接

package dh;

import java.io.UnsupportedEncodingException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
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.KeyAgreement;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.interfaces.DHPublicKey;
import javax.crypto.spec.DHParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;

/**
* 基于JDK的DH算法，工作模式采用ECB
*/
public class DHCoder {
private static final String ENCODING = "UTF-8";
private static final String FDC_KEY_ALGORITHM = "DH";//非对称加密密钥算法
private static final String DC_KEY_ALGORITHM = "AES";//产生本地密钥的算法（对称加密密钥算法）
private static final String CIPHER_ALGORITHM = "AES/ECB/PKCS5Padding";//加解密算法 格式：算法/工作模式/填充模式 注意：ECB不使用IV参数
private static final int FDC_KEY_SIZE = 512;//非对称密钥长度（512~1024之间的64的整数倍）

/**
* 生成甲方密钥对
*/
public static KeyPair initKey() throws NoSuchAlgorithmException{
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(FDC_KEY_ALGORITHM);//密钥对生成器
keyPairGenerator.initialize(FDC_KEY_SIZE);//指定密钥长度
KeyPair keyPair = keyPairGenerator.generateKeyPair();//生成密钥对
return keyPair;
}

/**
* 生成乙方密钥对
* @param key 甲方公钥
*/
public static KeyPair initKey(byte[] key) throws NoSuchAlgorithmException,
InvalidKeySpecException,
InvalidAlgorithmParameterException{
KeyFactory keyFactory = KeyFactory.getInstance(FDC_KEY_ALGORITHM);//密钥工厂
PublicKey publicKey = keyFactory.generatePublic(new X509EncodedKeySpec(key));//还原甲方公钥
DHParameterSpec dHParameterSpec = ((DHPublicKey)publicKey).getParams();

KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(keyFactory.getAlgorithm());//乙方密钥对生成器
keyPairGenerator.initialize(dHParameterSpec);//使用甲方公钥参数初始化乙方密钥对生成器
KeyPair keyPair = keyPairGenerator.generateKeyPair();//生成密钥对
return keyPair;
}

/**
* DH加密
* @param data     带加密数据
* @param keyByte  本地密钥，由getSecretKey(byte[] publicKey, byte[] privateKey)产生
*/
public static byte[] encrypt(String data, byte[] keyByte) throws NoSuchAlgorithmException,
NoSuchPaddingException,
InvalidKeyException,
IllegalBlockSizeException,
BadPaddingException,
UnsupportedEncodingException {
Key key = new SecretKeySpec(keyByte, DC_KEY_ALGORITHM);//生成本地密钥

Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, key);//设置加密模式并且初始化key
return cipher.doFinal(data.getBytes(ENCODING));
}

/**
* DH解密
* @param data        待解密数据为字节数组
* @param keyByte    本地密钥，由getSecretKey(byte[] publicKey, byte[] privateKey)产生
*/
public static byte[] decrypt(byte[] data, byte[] keyByte) throws NoSuchAlgorithmException,
NoSuchPaddingException,
InvalidKeyException,
IllegalBlockSizeException,
BadPaddingException {
Key key = new SecretKeySpec(keyByte, DC_KEY_ALGORITHM);//生成本地密钥
Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, key);
return cipher.doFinal(data);
}

/**
* 根据本方私钥与对方公钥构建本地密钥（即对称加密的密钥）
* @param publicKey        对方公钥
* @param privateKey    本方私钥
*/
public static byte[] getSecretKey(byte[] publicKey, byte[] privateKey) throws NoSuchAlgorithmException,
InvalidKeySpecException,
InvalidKeyException{
KeyFactory keyFactory = KeyFactory.getInstance(FDC_KEY_ALGORITHM);//密钥工厂
PublicKey pubkey = keyFactory.generatePublic(new X509EncodedKeySpec(publicKey));//还原公钥
PrivateKey prikey = keyFactory.generatePrivate(new PKCS8EncodedKeySpec(privateKey));//还原私钥

KeyAgreement keyAgreement = KeyAgreement.getInstance(keyFactory.getAlgorithm());
keyAgreement.init(prikey);
keyAgreement.doPhase(pubkey, true);
return keyAgreement.generateSecret(DC_KEY_ALGORITHM).getEncoded();//生成本地密钥（对称加密的密钥）
}

/**
* 获取公钥
*/
public static byte[] getPublicKey(KeyPair keyPair){
return keyPair.getPublic().getEncoded();
}

/**
* 获取私钥
*/
public static byte[] getPrivateKey(KeyPair keyPair){
return keyPair.getPrivate().getEncoded();
}

/**
* 测试
*/
public static void main(String[] args) throws NoSuchAlgorithmException,
InvalidKeySpecException,
InvalidAlgorithmParameterException,
InvalidKeyException,
NoSuchPaddingException,
IllegalBlockSizeException,
BadPaddingException,
UnsupportedEncodingException {
byte[] pubKey1;//甲方公钥
byte[] priKey1;//甲方私钥
byte[] key1;//甲方本地密钥
byte[] pubKey2;//乙方公钥
byte[] priKey2;//乙方私钥
byte[] key2;//乙方本地密钥

/*********************测试是否可以正确生成以上6个key，以及key1与key2是否相等*********************/
KeyPair keyPair1 = DHCoder.initKey();//生成甲方密钥对
pubKey1 = DHCoder.getPublicKey(keyPair1);
priKey1 = DHCoder.getPrivateKey(keyPair1);

KeyPair keyPair2 = DHCoder.initKey(pubKey1);//根据甲方公钥生成乙方密钥对
pubKey2 = DHCoder.getPublicKey(keyPair2);
priKey2 = DHCoder.getPrivateKey(keyPair2);

key1 = DHCoder.getSecretKey(pubKey2, priKey1);//使用对方公钥和自己私钥构建本地密钥
key2 = DHCoder.getSecretKey(pubKey1, priKey2);//使用对方公钥和自己私钥构建本地密钥

System.out.println("甲方公钥pubKey1-->"+Base64.encodeBase64String(pubKey1)+"@@pubKey1.length-->"+pubKey1.length);
System.out.println("甲方私钥priKey1-->"+Base64.encodeBase64String(priKey1)+"@@priKey1.length-->"+priKey1.length);
System.out.println("乙方公钥pubKey2-->"+Base64.encodeBase64String(pubKey2)+"@@pubKey2.length-->"+pubKey2.length);
System.out.println("乙方私钥priKey2-->"+Base64.encodeBase64String(priKey2)+"@@priKey2.length-->"+priKey2.length);
System.out.println("甲方密钥key1-->"+Base64.encodeBase64String(key1));
System.out.println("乙方密钥key2-->"+Base64.encodeBase64String(key2));

/*********************测试甲方使用本地密钥加密数据向乙方发送，乙方使用本地密钥解密数据*********************/
System.out.println("甲方-->乙方");
String data = "找一个好姑娘啊！";
byte[] encodeStr = DHCoder.encrypt(data, key1);
System.out.println("甲方加密后的数据-->"+Base64.encodeBase64String(encodeStr));
byte[] decodeStr = DHCoder.decrypt(encodeStr, key2);
System.out.println("乙方解密后的数据-->"+new String(decodeStr,"UTF-8"));

/*********************测试乙方使用本地密钥加密数据向甲方发送，甲方使用本地密钥解密数据*********************/
System.out.println("乙方-->甲方");
String data2 = "找一个好姑娘啊！";
byte[] encodeStr2 = DHCoder.encrypt(data2, key2);
System.out.println("乙方加密后的数据-->"+Base64.encodeBase64String(encodeStr2));
byte[] decodeStr2 = DHCoder.decrypt(encodeStr, key1);
System.out.println("甲方解密后的数据-->"+new String(decodeStr2,"UTF-8"));
}
}

典型非对称加密算法-RSA

package rsa;

import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
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 java.util.HashMap;
import java.util.Map;

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

import org.apache.commons.codec.binary.Base64;

public abstract class RSACoder {
private static final String KEY_ALGORITHM= "RSA";
private static final int KEY_SIZE=512;
private static final String PUBLIC_KEY = "RSAPublicKey";
private static final String PRIVATE_KEY = "RSAPrivateKey";

public static Map<String,Object> initKey() throws NoSuchAlgorithmException{
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
keyPairGen.initialize(KEY_SIZE);
KeyPair keyPair = keyPairGen.generateKeyPair();
//生成密钥当然要生成最丰富的啦
RSAPublicKey publicKey = (RSAPublicKey)keyPair.getPublic();
RSAPrivateKey privateKey = (RSAPrivateKey)keyPair.getPrivate();

Map<String,Object> keyMap = new HashMap<String,Object>(2);
keyMap.put(PUBLIC_KEY, publicKey);
keyMap.put(PRIVATE_KEY, privateKey);
return keyMap;

}

public static byte[] encryptByPrivateKey(byte[] data,byte[] priKey) throws NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException{
PKCS8EncodedKeySpec x509EncodedKeySpec = new PKCS8EncodedKeySpec(priKey);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
PrivateKey privateKey = keyFactory.generatePrivate(x509EncodedKeySpec);

Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
return cipher.doFinal(data);

}

public static byte[] decryptByPublicKey(byte[] data,byte[] pubKey) throws NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException{
X509EncodedKeySpec pkcs8EncodedKeySpec = new X509EncodedKeySpec(pubKey);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
PublicKey publicKey = keyFactory.generatePublic(pkcs8EncodedKeySpec);

Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, publicKey);
return cipher.doFinal(data);
}

public static byte[] getPrivateKey(Map<String,Object> keyMap){
RSAPrivateKey privateKey = (RSAPrivateKey) keyMap.get(PRIVATE_KEY);
return privateKey.getEncoded();
}

public static byte[] getPublicKey(Map<String,Object> keyMap){
RSAPublicKey publicKey = (RSAPublicKey)keyMap.get(PUBLIC_KEY);
return publicKey.getEncoded();
}

public static void main(String[] args) {
try {
byte[] privateKey = null;
byte[] publicKey = null;
Map<String,Object> keyMap = RSACoder.initKey();
publicKey = RSACoder.getPublicKey(keyMap);
privateKey = RSACoder.getPrivateKey(keyMap);
System.err.println("公钥：\n"+Base64.encodeBase64String(publicKey));
System.err.println("私钥：\n"+Base64.encodeBase64String(privateKey));

System.err.println("\n--私钥加密，公钥解密--");
String input1 = "RSA加密算法";
System.err.println("原文：\n"+input1);
byte[] data1 = input1.getBytes();
byte[] encodedata1 = RSACoder.encryptByPrivateKey(data1, privateKey);
System.err.println("加密后：\n"+Base64.encodeBase64String(encodedata1));
byte[] decodedata1 = RSACoder.decryptByPublicKey(encodedata1, publicKey);
System.err.println("解密后：\n"+Base64.encodeBase64String(decodedata1));
String output1 = new String(decodedata1);
System.out.println("结果：\n"+output1);

System.out.println("结果：\n"+ (input1.equals(output1)));
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (InvalidKeySpecException e) {
e.printStackTrace();
} catch (NoSuchPaddingException e) {
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
} catch (BadPaddingException e) {
e.printStackTrace();
}
}
}

ElGamal

package elGamal;

import java.security.AlgorithmParameterGenerator;
import java.security.AlgorithmParameters;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.Security;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.InvalidParameterSpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

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

import org.apache.commons.codec.binary.Base64;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

public abstract class ElGamalCoder {
public static final String KEY_ALGORITHM = "ElGamal";
private static final int KEY_SIZE = 256;
private static final String PUBLIC_KEY = "ElGamalPublicKey";
private static final String PRIVATE_KEY = "ElGamalPrivateKey";

public static byte[] decryptByPrivateKey(byte[] data, byte[] key)
throws NoSuchAlgorithmException, InvalidKeySpecException,
NoSuchPaddingException, InvalidKeyException,
IllegalBlockSizeException, BadPaddingException {
Security.addProvider(new BouncyCastleProvider());
PKCS8EncodedKeySpec pkc = new PKCS8EncodedKeySpec(key);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key privateKey = keyFactory.generatePrivate(pkc);

Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, privateKey);
return cipher.doFinal(data);

}

public static byte[] encryptByPublicKey(byte[] data, byte[] key)
throws NoSuchAlgorithmException, InvalidKeySpecException,
NoSuchPaddingException, InvalidKeyException,
IllegalBlockSizeException, BadPaddingException {
Security.addProvider(new BouncyCastleProvider());
X509EncodedKeySpec x509 = new X509EncodedKeySpec(key);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key publicKey = keyFactory.generatePublic(x509);

Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
return cipher.doFinal(data);

}

public static Map<String, Object> initKey()
throws NoSuchAlgorithmException, InvalidParameterSpecException,
InvalidAlgorithmParameterException {
Security.addProvider(new BouncyCastleProvider());
AlgorithmParameterGenerator apg = AlgorithmParameterGenerator
.getInstance(KEY_ALGORITHM);
apg.init(KEY_SIZE);
AlgorithmParameters params = apg.generateParameters();
DHParameterSpec dhParams = params
.getParameterSpec(DHParameterSpec.class);

KeyPairGenerator keyPairGene = KeyPairGenerator
.getInstance(KEY_ALGORITHM);
keyPairGene.initialize(dhParams, new SecureRandom());

// keyPairGene.initialize(KEY_SIZE, new SecureRandom());
KeyPair keyPair = keyPairGene.generateKeyPair();
PublicKey publicKey = keyPair.getPublic();
PrivateKey privateKey = keyPair.getPrivate();

Map<String, Object> keyMap = new HashMap<String, Object>(2);
keyMap.put(PUBLIC_KEY, publicKey);
keyMap.put(PRIVATE_KEY, privateKey);
return keyMap;
}

public static byte[] getPrivateKey(Map<String, Object> keyMap) {
Key key = (Key) keyMap.get(PRIVATE_KEY);
return key.getEncoded();
}

public static byte[] getPublicKey(Map<String, Object> keyMap) {
Key key = (Key) keyMap.get(PUBLIC_KEY);
return key.getEncoded();
}

public static void main(String[] args) {
try {
byte[] privateKey = null;
byte[] publicKey = null;

Map<String, Object> keyMap = ElGamalCoder.initKey();
publicKey = ElGamalCoder.getPublicKey(keyMap);
privateKey = ElGamalCoder.getPrivateKey(keyMap);
System.err.println("公钥：\n" + Base64.encodeBase64String(publicKey));
System.err.println("私钥：\n" + Base64.encodeBase64String(privateKey));

System.err.println("\n--公钥加密，私钥解密--");
String input1 = "ElGamal加密算法";
System.err.println("原文：\n" + input1);
byte[] data1 = input1.getBytes();
byte[] encodedata1 = ElGamalCoder.encryptByPublicKey(data1,publicKey);
System.err.println("加密后：\n" + Base64.encodeBase64String(encodedata1));
byte[] decodedata1 = ElGamalCoder.decryptByPrivateKey(encodedata1,privateKey);
System.err.println("解密后：\n" + Base64.encodeBase64String(decodedata1));
String output1 = new String(decodedata1);
System.err.println("结果：\n" + output1);
System.out.println("结果：\n" + (input1.equals(output1)));
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (InvalidParameterSpecException e) {
e.printStackTrace();
} catch (InvalidAlgorithmParameterException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvalidKeySpecException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (NoSuchPaddingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (BadPaddingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}
}