/**
 * 非對(duì)稱加密之：DH加密
 * 非對(duì)稱DH，是安全性基于在有限域中計(jì)算離散對(duì)數(shù)的難度的一種加密算法。
 * 可用于密鑰分發(fā)，但不能用于加/解密報(bào)文。DH即Diffie-Hellman算法的簡寫，也縮寫為D-H算法。
 * D-H加密算法的核心思想就是大素?cái)?shù)不可分解質(zhì)因數(shù)的數(shù)學(xué)理論方法。
 * @description：
 * @date 2015-10-29 上午9:08:14
 */
public class EncryptDH {
private static String dhStr = "encrypt test by DH";
public static void main(String[] args) {
jdkDh();
}
private static void jdkDh() {
try {
// 初始化發(fā)送方密鑰
KeyPairGenerator senderKeyPairGenerator = KeyPairGenerator.getInstance("DH");
senderKeyPairGenerator.initialize(512);
KeyPair senderKeyPair = senderKeyPairGenerator.generateKeyPair();
byte[] senderPublicKeyEnc = senderKeyPair.getPublic().getEncoded();// 發(fā)送方的公鑰，發(fā)送給接受方，發(fā)送方式多種，比如文件，網(wǎng)絡(luò)等
// 初始化接受方密鑰
KeyFactory receiverKeyFactory = KeyFactory.getInstance("DH");
X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(senderPublicKeyEnc);
PublicKey receiverPublicKey = receiverKeyFactory.generatePublic(x509EncodedKeySpec);
DHParameterSpec dhParameterSpec = ((DHPublicKey) receiverPublicKey).getParams();
KeyPairGenerator receiverKeyPairGenerator = KeyPairGenerator.getInstance("DH");
receiverKeyPairGenerator.initialize(dhParameterSpec);
KeyPair receiveKeyPair = receiverKeyPairGenerator.generateKeyPair();
PrivateKey receiverPrivateKey = receiveKeyPair.getPrivate();
byte[] receiverPublicKeyEnc = receiveKeyPair.getPublic().getEncoded();
// 密鑰構(gòu)建
KeyAgreement receiverKeyAgreement = KeyAgreement.getInstance("DH");
receiverKeyAgreement.init(receiverPrivateKey);
receiverKeyAgreement.doPhase(receiverPublicKey, true);
SecretKey receiverSecretKey = receiverKeyAgreement.generateSecret("DES");
KeyFactory senderKeyFactory = KeyFactory.getInstance("DH");
x509EncodedKeySpec = new X509EncodedKeySpec(receiverPublicKeyEnc);
PublicKey senderPublicKey = senderKeyFactory.generatePublic(x509EncodedKeySpec);
KeyAgreement senderKeyAgreement = KeyAgreement.getInstance("DH");
senderKeyAgreement.init(senderKeyPair.getPrivate());
senderKeyAgreement.doPhase(senderPublicKey, true);
SecretKey snederSecretKey = senderKeyAgreement.generateSecret("DES");
if (Objects.equals(receiverSecretKey, snederSecretKey)) {
System.out.println("雙方密鑰相同");
}
// 加密
Cipher cipher = Cipher.getInstance("DES");
cipher.init(Cipher.ENCRYPT_MODE, snederSecretKey);
byte[] result = cipher.doFinal(dhStr.getBytes());
System.out.println("DH加密后為：" + Base64.encode(result));
// 解密
cipher.init(Cipher.DECRYPT_MODE, receiverSecretKey);
result = cipher.doFinal(result);
System.out.println("DH解密后為：" + new String(result));
}
catch (Exception e) {
e.printStackTrace();
}
}
}

/**
 * 非對(duì)稱加密之：RSA加密
 * @description：
 * RSA公鑰加密算法是1977年由羅納德·李維斯特（Ron Rivest）、阿迪·薩莫爾（Adi Shamir）和倫納德·阿德曼（Leonard Adleman）一起提出的。
 * 1987年首次公布，當(dāng)時(shí)他們?nèi)硕荚诼槭±砉W(xué)院工作。RSA就是他們?nèi)诵帐祥_頭字母拼在一起組成的。
 * RSA是目前最有影響力的公鑰加密算法，它能夠抵抗到目前為止已知的絕大多數(shù)密碼攻擊，已被ISO推薦為公鑰數(shù)據(jù)加密標(biāo)準(zhǔn)。
 * 今天只有短的RSA鑰匙才可能被強(qiáng)力方式解破。到2008年為止，世界上還沒有任何可靠的攻擊RSA算法的方式。只要其鑰匙的長度足夠長，用RSA加密的信息實(shí)際上是不能被解破的。
 * 但在分布式計(jì)算和量子計(jì)算機(jī)理論日趨成熟的今天，RSA加密安全性受到了挑戰(zhàn)。
 * RSA算法基于一個(gè)十分簡單的數(shù)論事實(shí)：將兩個(gè)大素?cái)?shù)相乘十分容易，但是想要對(duì)其乘積進(jìn)行因式分解卻極其困難，因此可以將乘積公開作為加密密鑰。
 * @date 2015-10-29 上午9:08:14
 */
public class EncryptRSA {
private static String rsaStr = "encrypt test by ElGamal";
public static void main(String[] args) {
jdkRSA();
}
private static void jdkRSA() {
try {
// 初始化密鑰
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
keyPairGenerator.initialize(512);
KeyPair keyPair = keyPairGenerator.generateKeyPair();
RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();
System.out.println("RSA公鑰：" + Base64.encode(rsaPublicKey.getEncoded()));
System.out.println("RSA私鑰：" + Base64.encode(rsaPrivateKey.getEncoded()));
// 私鑰加密，公鑰解密--加密
PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
byte[] result = cipher.doFinal(rsaStr.getBytes());
System.out.println("RSA私鑰加密，公鑰解密--加密：" + Base64.encode(result));
// 私鑰加密，公鑰解密--解密
X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
keyFactory = KeyFactory.getInstance("RSA");
PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, publicKey);
result = cipher.doFinal(result);
System.out.println("RSA私鑰加密，公鑰解密--解密：" + new String(result));
// 公鑰加密，私鑰解密--加密
x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
keyFactory = KeyFactory.getInstance("RSA");
publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
result = cipher.doFinal(rsaStr.getBytes());
System.out.println("公鑰加密，私鑰解密--加密：" + Base64.encode(result));
// 公鑰加密，私鑰解密--解密
pkcs8EncodedKeySpec=new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
keyFactory = KeyFactory.getInstance("RSA");
privateKey= keyFactory.generatePrivate(pkcs8EncodedKeySpec);
cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, privateKey);
result = cipher.doFinal(result);
System.out.println("公鑰加密，私鑰解密--解密：" + new String(result));
}
catch (Exception e) {
e.printStackTrace();
}
}
}

/**
 * 非對(duì)稱加密之：ElGamal加密
 * @description：
 * ElGamal算法，是一種較為常見的加密算法，它是基于1984年提出的公鑰密碼體制和橢圓曲線加密體系。
 * 既能用于數(shù)據(jù)加密也能用于數(shù)字簽名，其安全性依賴于計(jì)算有限域上離散對(duì)數(shù)這一難題。
 * 在加密過程中，生成的密文長度是明文的兩倍，且每次加密后都會(huì)在密文中生成一個(gè)隨機(jī)數(shù)K，
 * 在密碼中主要應(yīng)用離散對(duì)數(shù)問題的幾個(gè)性質(zhì)：求解離散對(duì)數(shù)（可能）是困難的，而其逆運(yùn)算指數(shù)運(yùn)算可以應(yīng)用平方-乘的方法有效地計(jì)算。
 * 也就是說，在適當(dāng)?shù)娜篏中，指數(shù)函數(shù)是單向函數(shù)。
 * @date 2015-10-29 上午9:08:14
 */
public class EncrypElGamal {
private static String rsaStr = "encrypt test by ElGamal";
public static void main(String[] args) {
jdkRSA();
}
private static void jdkRSA() {
try {
// 公鑰加密，私鑰解密
// Security.addProvider(new BouncyCastleProvider());//需要添加bouncycastleprovider jar
//初始化密鑰
AlgorithmParameterGenerator algorithmParameterGenerator=AlgorithmParameterGenerator.getInstance("ElGamal");
algorithmParameterGenerator.init(256);
AlgorithmParameters algorithmParameters=algorithmParameterGenerator.generateParameters();
DHParameterSpec dhParameterSpec=algorithmParameters.getParameterSpec(DHParameterSpec.class);
KeyPairGenerator keyPairGenerator=KeyPairGenerator.getInstance("ElGamal");
keyPairGenerator.initialize(dhParameterSpec,new SecureRandom());
KeyPair keyPair=keyPairGenerator.generateKeyPair();
PublicKey publicKey=keyPair.getPublic();
PrivateKey privateKey=keyPair.getPrivate();
System.out.println("ElGamal加密公鑰："+Base64.encode(publicKey.getEncoded()));
System.out.println("ElGamal加密私鑰："+Base64.encode(privateKey.getEncoded()));
//加密解密同Rsa是一樣的
}
catch (Exception e) {
e.printStackTrace();
}
}
}