/*
* JEF - Copyright 2009-2010 Jiyi (mr.jiyi@gmail.com)
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package jef.tools.security;
import java.io.IOException;
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.PrivateKey;
import java.security.PublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.KeyAgreement;
import javax.crypto.SecretKey;
import javax.crypto.interfaces.DHPublicKey;
import javax.crypto.spec.DHParameterSpec;
import jef.common.wrapper.Holder;
import jef.tools.security.EncrypterUtil.Transport;
/**
* 公开密钥生成体制实现
* 基于Diffie-Hellman算法
* 公开密钥密码体制的奠基人Diffie和Hellman所提出的 "指数密钥一致协议"(Exponential Key Agreement Protocol),
* 该协议不要求别的安全性 先决条件,允许两名用户在公开媒体上交换信息以生成"一致"的,可以共享的密钥。
* 在这种协商中，被交换的是双方的公钥，基于非对称加密的数学依据，是很难根据公钥推算出双方的私钥的。
* 从而也就几乎不可能获得协商后的密钥。
* @author Jiyi
*/
public class KeyConsult {
private KeyPairGenerator kpairGen;
private KeyFactory keyFac;
{
try {
kpairGen = KeyPairGenerator.getInstance("DH");
keyFac = KeyFactory.getInstance("DH");
keyAgree = KeyAgreement.getInstance("DH");
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException(e);
}
}
private PrivateKey key;
private PublicKey pubKey;
private KeyAgreement keyAgree;
private PublicKey phaseToDo = null;
/**
* 发送公钥给对方
*
* @param t
*/
public void send(Transport t) {
byte[] data=pubKey.getEncoded();
// System.out.println("sending:"+ StringUtils.byte2hex(data));
try {
t.send(data);
} catch (IOException e) {
throw new IllegalStateException();
}
}
/**
* 创建一个协商会话
*/
public KeyConsult() {
kpairGen.initialize(512);
KeyPair aliceKpair = kpairGen.generateKeyPair();
this.key = aliceKpair.getPrivate();
try {
keyAgree.init(key);// 用本地私钥初始化
} catch (InvalidKeyException e) {
throw new RuntimeException(e);
}
this.pubKey = aliceKpair.getPublic();
}
/**
* 当接收到对方的协商后，创建一个协商会话
*/
public KeyConsult(byte[] alicePubKeyEnc) {
// System.out.println("create from received.");
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(alicePubKeyEnc);
try {
PublicKey received = keyFac.generatePublic(x509KeySpec);
/*
* B必须用相同的参数初始化的他的DH KEY对,所以要从A发给他的公开密钥,中读出参数,再用这个参数初始化他的 DH key对
*/
DHParameterSpec dhParamSpec = ((DHPublicKey) received).getParams();
kpairGen.initialize(dhParamSpec);
KeyPair bobKpair = kpairGen.generateKeyPair();
this.key = bobKpair.getPrivate();
keyAgree.init(key);
this.pubKey = bobKpair.getPublic();
this.phaseToDo = received;
} catch (InvalidKeySpecException e) {
throw new RuntimeException(e);
} catch (InvalidAlgorithmParameterException e) {
throw new RuntimeException(e);
} catch (InvalidKeyException e) {
throw new RuntimeException(e);
}
}
/**
* 当每一次收到对方的公钥后，就加密一次，最后一次如果要生成key,需要调用generate=true
*
* @param recKey
* @param generate
*/
private void doPhase(boolean generate) {
if (phaseToDo == null)
return;
try {
keyAgree.doPhase(phaseToDo, generate);
phaseToDo = null;
} catch (InvalidKeyException e) {
throw new RuntimeException(e);
} catch (IllegalStateException e) {
throw new RuntimeException(e);
}
}
/**
* 要生成之前必须先调用doPhase(xx,true)
*
* @return
*/
public SecretKey generateKey(String typeNeed) {
if (phaseToDo != null)
this.doPhase(true);
try {
SecretKey bobDesKey = keyAgree.generateSecret(typeNeed);
return bobDesKey;
} catch (InvalidKeyException e) {
throw new RuntimeException(e);
} catch (IllegalStateException e) {
throw new RuntimeException(e);
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException(e);
}
}
public void receive(byte[] data) {
receive(data,0,data.length);
}
public void receive(byte[] data,int offset,int len) {
try {
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(data);
PublicKey received = keyFac.generatePublic(x509KeySpec);
if (phaseToDo != null)
this.doPhase(false);
this.phaseToDo = received;
} catch (InvalidKeySpecException e) {
throw new RuntimeException(e);
}
}
public static void test(){
final Holder<byte[]> h=new Holder<byte[]>();
Transport t=new Transport(){
public void send(byte[] encoded) {
h.set(encoded);
}
};
//A发起
KeyConsult a=new KeyConsult();
a.send(t);
//B C接收
KeyConsult b=new KeyConsult(h.get());
b.send(t);
a.receive(h.get());
SecretKey key1=a.generateKey("DES");
SecretKey key2=b.generateKey("DES");
System.out.println(key1);
System.out.println(key2);
System.out.println(key1.equals(key2));
}
}