每日一得--非对称加密算法之（EIGamal）

import java.security.AlgorithmParameterGenerator;
import java.security.AlgorithmParameters;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.Security;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;
import javax.crypto.spec.DHParameterSpec;
import org.apache.commons.codec.binary.Base64;
import org.bouncycastle.jce.interfaces.ElGamalPrivateKey;
import org.bouncycastle.jce.interfaces.ElGamalPublicKey;
import org.bouncycastle.jce.provider.BouncyCastleProvider;


public class EIGamalMain {
private static String str= "husq EIGamal test";
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
bcEIGamal();
}

public static void bcEIGamal(){
try{
Security.addProvider(new BouncyCastleProvider());

//1 初始化秘钥
AlgorithmParameterGenerator algorithmParameterGenerator = AlgorithmParameterGenerator.getInstance("ElGamal");
algorithmParameterGenerator.init(256);
AlgorithmParameters algorithmParameters = algorithmParameterGenerator.generateParameters();
DHParameterSpec dhParameterSpec = (DHParameterSpec)algorithmParameters.getParameterSpec(DHParameterSpec.class);

KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("ElGamal");
keyPairGenerator.initialize(dhParameterSpec,new SecureRandom());
KeyPair keyPair = keyPairGenerator.generateKeyPair();
PublicKey elGamalPublicKey = keyPair.getPublic();
PrivateKey elGamalPrivateKey = keyPair.getPrivate();
System.out.println("public key : "+ Base64.encodeBase64String(elGamalPublicKey.getEncoded()));
System.out.println("private key : "+ Base64.encodeBase64String(elGamalPrivateKey.getEncoded()));

//2 私钥加密，公钥解密---加密
PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(elGamalPrivateKey.getEncoded());
KeyFactory kFactory = KeyFactory.getInstance("ElGamal");
PrivateKey privateKey = kFactory.generatePrivate(pkcs8EncodedKeySpec);
Cipher cipher = Cipher.getInstance("ElGamal");
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
byte[] result = cipher.doFinal(str.getBytes());
System.out.println("私钥加密，公钥解密---加密 :"+ Base64.encodeBase64String(result));


//3,私钥加密，公钥解密--解密
X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(elGamalPublicKey.getEncoded());
kFactory = KeyFactory.getInstance("ElGamal");
PublicKey publicKey = kFactory.generatePublic(x509EncodedKeySpec);
cipher = Cipher.getInstance("ElGamal");
cipher.init(Cipher.DECRYPT_MODE, publicKey);
result = cipher.doFinal(result);
System.out.println("私钥加密，公钥解密---解密："+ new String(result));

//4,公钥加密，私钥解密--加密
x509EncodedKeySpec  = new X509EncodedKeySpec(elGamalPublicKey.getEncoded());
kFactory = KeyFactory.getInstance("ElGamal");
publicKey = kFactory.generatePublic(x509EncodedKeySpec);
cipher = Cipher.getInstance("ElGamal");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
result = cipher.doFinal(str.getBytes());
System.out.println("公钥加密，私钥解密---加密："+Base64.encodeBase64String(result));

//5,公钥加密，私钥解密--解密
pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(elGamalPrivateKey.getEncoded());
kFactory = KeyFactory.getInstance("ElGamal");
privateKey = kFactory.generatePrivate(pkcs8EncodedKeySpec);
cipher = Cipher.getInstance("ElGamal");
cipher.init(Cipher.DECRYPT_MODE, privateKey);
cipher.doFinal(result);
System.out.println("公钥加密，私钥解密---解密："+new String(result));
}catch(Exception e){
e.printStackTrace();
}
}


}