Diffie Hellman密钥交换

adamdudu3 2013-03-08 04:51:59

求一段代码：
我想用Diffie Hellman 来交换128位的密钥，有没有什么好的方法呢？
谢谢！
这里是我的发送端的：

package com.example.try9.Encryption;



import java.security.AlgorithmParameterGenerator;

import java.security.AlgorithmParameters;

import java.security.InvalidAlgorithmParameterException;

import java.security.InvalidKeyException;

import java.security.KeyFactory;

import java.security.KeyPair;

import java.security.KeyPairGenerator;

import java.security.NoSuchAlgorithmException;

import java.security.PublicKey;

import java.security.spec.InvalidKeySpecException;

import java.security.spec.InvalidParameterSpecException;

import java.security.spec.X509EncodedKeySpec;



import javax.crypto.KeyAgreement;

import javax.crypto.interfaces.DHPublicKey;

import javax.crypto.spec.DHParameterSpec;



public class SenderDiffieHellman {

private static KeyAgreement KeyAgree;



	public static String Generator() throws InvalidParameterSpecException, NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException {

//初始化密钥对的参数

		DHParameterSpec dhSkipParamSpec;

		AlgorithmParameterGenerator paramGen = AlgorithmParameterGenerator

				.getInstance("DH");

		paramGen.init(256);

		AlgorithmParameters params = paramGen.generateParameters();

		dhSkipParamSpec = (DHParameterSpec) params

				.getParameterSpec(DHParameterSpec.class);

//创建一个密钥对

		KeyPairGenerator KpairGen = KeyPairGenerator.getInstance("DH");

		KpairGen.initialize(dhSkipParamSpec);

		KeyPair Kpair = KpairGen.generateKeyPair();



		/** 创建密钥协议，产生私钥 */



		KeyAgree = KeyAgreement.getInstance("DH");

		KeyAgree.init(Kpair.getPrivate());



		/** 产生公钥 */



		byte[] PubKeyEnc = Kpair.getPublic().getEncoded();

		String pubKeyStr=new String(PubKeyEnc);

		System.out.println(pubKeyStr);

		return pubKeyStr;

	}

	

	//产生共享密钥，解析来自另一端的公钥

	public static String Parser(String pubKeyStr) throws InvalidKeySpecException, NoSuchAlgorithmException, InvalidKeyException, IllegalStateException{

		 byte[] pubKeyEnc=pubKeyStr.getBytes();

		 KeyFactory KeyFac = KeyFactory.getInstance("DH");

	        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(pubKeyEnc);

	        PublicKey PubKey = KeyFac.generatePublic(x509KeySpec);

	        

	        KeyAgree.doPhase(PubKey, true);

	        byte[] SharedSecret = KeyAgree.generateSecret();		

	        String sharedSecretStr=new String (SharedSecret);

	        return sharedSecretStr;

	}

}

这里是我的接收端的：

package com.example.try2.Decryption;



import java.security.InvalidAlgorithmParameterException;

import java.security.InvalidKeyException;

import java.security.KeyFactory;

import java.security.KeyPair;

import java.security.KeyPairGenerator;

import java.security.NoSuchAlgorithmException;

import java.security.PublicKey;

import java.security.spec.InvalidKeySpecException;

import java.security.spec.X509EncodedKeySpec;



import javax.crypto.KeyAgreement;

import javax.crypto.interfaces.DHPublicKey;

import javax.crypto.spec.DHParameterSpec;



public class ReceiverDiffieHellman {

	// 收到sender的配置之后初始化自己的配置，然后利用这个配置并结合自己的密钥对产生相应的公钥和私钥，

public static String resultPubKsyStr;	

public static String sharedSecretStr;



	public static void ParserAndGenerator(String pubKeyStr) throws NoSuchAlgorithmException, InvalidKeySpecException, InvalidAlgorithmParameterException, InvalidKeyException {

		byte[] pubKeyEnc=pubKeyStr.getBytes();

		KeyFactory KeyFac = KeyFactory.getInstance("DH");

		

		X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(pubKeyEnc);

		

		PublicKey PubKey = KeyFac.generatePublic(x509KeySpec);

		DHParameterSpec dhParamSpec = ((DHPublicKey)PubKey).getParams();

		

		  KeyPairGenerator KpairGen = KeyPairGenerator.getInstance("DH");

	        KpairGen.initialize(dhParamSpec);

	        KeyPair Kpair = KpairGen.generateKeyPair();

	        //产生了自己的私钥用于未来的计算

	        KeyAgreement KeyAgree = KeyAgreement.getInstance("DH");

	        KeyAgree.init(Kpair.getPrivate());

	        KeyAgree.doPhase(PubKey, true);	        

	        byte[] SharedSecret = KeyAgree.generateSecret();

	       sharedSecretStr=new String(SharedSecret);

	        //产生公钥用于屏幕显示

	        byte[] PubKeyEnc = Kpair.getPublic().getEncoded();

	        resultPubKsyStr=new String(PubKeyEnc);	

	        

	        

	        System.out.println("ss:"+sharedSecretStr);

	        System.out.println("re"+resultPubKsyStr);

	        System.out.println("I'm OK now");

	        

	}

}

总是报错：java.security.spec.InvalidKeySpecException: Inappropriate key specification
at com.sun.crypto.provider.DHKeyFactory.engineGeneratePublic(DHKeyFactory.java:87)
at java.security.KeyFactory.generatePublic(Unknown Source)
at test.Generator(test.java:51)
at test.main(test.java:63)

不知道是什么原因？
弄了一天了，谢谢！

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