package com.imooc.security.dsa;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.interfaces.DSAPrivateKey;
import java.security.interfaces.DSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import org.apache.commons.codec.binary.Hex;
public class ImoocDSA {
  private static String src = "cakin24 security dsa";
  public static void main(String[] args) {
    jdkDSA();
  }
  public static void jdkDSA() {
    try {
      //1.初始化密鑰
      KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("DSA");
      keyPairGenerator.initialize(512);
      KeyPair keyPair = keyPairGenerator.generateKeyPair();
      DSAPublicKey dsaPublicKey = (DSAPublicKey) keyPair.getPublic();
      DSAPrivateKey dsaPrivateKey = (DSAPrivateKey)keyPair.getPrivate();
      //2.執行簽名
      PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(dsaPrivateKey.getEncoded());
      KeyFactory keyFactory = KeyFactory.getInstance("DSA");
      PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
      Signature signature = Signature.getInstance("SHA1withDSA");
      signature.initSign(privateKey);
      signature.update(src.getBytes());
      byte[] result = signature.sign();
      System.out.println("jdk dsa sign : " + Hex.encodeHexString(result));
      //3.驗證簽名
      X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(dsaPublicKey.getEncoded());
      keyFactory = KeyFactory.getInstance("DSA");
      PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
      signature = Signature.getInstance("SHA1withDSA");
      signature.initVerify(publicKey);
      signature.update(src.getBytes());
      boolean bool = signature.verify(result);
      System.out.println("jdk dsa verify : " + bool);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}