信息加密之非对称加密DH算法

　　非对称加密算法是相对于对称加密算法来说的，对于对称加密算法请查阅之前的总结，今天为大家介绍一下DH算法，DH是一种密钥交换算法，接收方根据发送方加密时的密钥，生成接收方解密密钥。下面就一起来学习一下吧：

初始化发送方密钥：

KeyPairGenerator sendKeyPairGenerator = KeyPairGenerator.getInstance("DH");
            sendKeyPairGenerator.initialize(512);
            KeyPair sendKeyPair = sendKeyPairGenerator.generateKeyPair();
            byte[] sendPublicKeyEnc = sendKeyPair.getPublic().getEncoded();//生成发送方公钥，发送给接收方（网络、文件...）

初始化接收方密钥：

KeyFactory receiverKeyFactory = KeyFactory.getInstance("DH");
            X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(sendPublicKeyEnc);
            PublicKey receivePublicKey = receiverKeyFactory.generatePublic(x509EncodedKeySpec);
            DHParameterSpec dhParameterSpec = ((DHPublicKey)receivePublicKey).getParams();
            KeyPairGenerator receiverKeyPairGenerator = KeyPairGenerator.getInstance("DH");
            receiverKeyPairGenerator.initialize(dhParameterSpec);
            KeyPair receiverKeyPair = receiverKeyPairGenerator.generateKeyPair();
            PrivateKey receiverPrivateKey = receiverKeyPair.getPrivate();
            byte[] receiverPublicKeyEnc = receiverKeyPair.getPublic().getEncoded();

构建接收方密钥：

KeyAgreement receiverKeyAgreement = KeyAgreement.getInstance("DH");
            receiverKeyAgreement.init(receiverPrivateKey);
            receiverKeyAgreement.doPhase(receivePublicKey, true);
            
            SecretKey receiverDESKey = receiverKeyAgreement.generateSecret("DES");//接收方Key

构建发送方密钥：

KeyFactory sendKeyFactory = KeyFactory.getInstance("DH");
            x509EncodedKeySpec = new X509EncodedKeySpec(receiverPublicKeyEnc);
            PublicKey sendPublicKey = sendKeyFactory.generatePublic(x509EncodedKeySpec);
            
            KeyAgreement sendKeyAgreement = KeyAgreement.getInstance("DH");
            sendKeyAgreement.init(sendKeyPair.getPrivate());
            sendKeyAgreement.doPhase(sendPublicKey, true);
            
            SecretKey sendDESKey = sendKeyAgreement.generateSecret("DES");//发送方Key

发送方加密：

Cipher sendCipher = Cipher.getInstance("DES");
            sendCipher.init(Cipher.ENCRYPT_MODE, sendDESKey);
            byte[] sendResult = sendCipher.doFinal(src.getBytes());
            System.out.println("sendResult ："+Hex.encodeHexString(sendResult));

接收方解密：

Cipher receiverCipher = Cipher.getInstance("DES");
            receiverCipher.init(Cipher.DECRYPT_MODE, receiverDESKey);
            byte[] receiverResult = receiverCipher.doFinal(sendResult);
            System.out.println("receiverResult : "+new String (receiverResult));

　　基于密钥交换的非对称加密算法（DH）,到这里就总结完毕了。