package com.albedo.security;

/**
 * DSA 加解密實(shí)現(xiàn)
 */
public class ECDSAUtils extends Base {

  //字符編碼
  public static final String ALGORITHM = "EC";
  public static final String SIGN_ALGORITHM = "SHA1withECDSA";


  /**
   * ECDSA 驗(yàn)簽
   *
   * @param sign   加密簽名
   * @param str    加密字符串
   * @param publicKey 公鑰
   * @return 密文
   * @throws Exception 加密過程中的異常信息
   */
  public static boolean verify(String sign, String str, String publicKey) throws Exception {
    return verify(sign, str, publicKey, ALGORITHM, SIGN_ALGORITHM);
  }

  /**
   * ECDSA 簽名
   *
   * @param str    加密字符串
   * @param privateKey 私鑰
   * @return 銘文
   * @throws Exception 解密過程中的異常信息
   */
  public static String sign(String str, String privateKey) throws Exception {
    return sign(str, privateKey, ALGORITHM, SIGN_ALGORITHM);
  }


  public static void main(String[] args) throws Exception {
    String publicKey = getPublicKey(ALGORITHM, 512);
    String privateKey = getPrivateKey(ALGORITHM, 512);
    String message = "我要測(cè)試DSA";
    String sign = sign(message, privateKey);
    System.out.println(verify(sign, message, publicKey));
  }
}

package com.albedo.security;

import com.albedo.num.ByteUtils;

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.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Objects;

class Base {
  static KeyPair keyPair;

  /**
   * 生成密鑰實(shí)際方法，可以使用多種方式
   * 一篇文檔提供一下多種方式
   * { "DSA", "SHA1withDSA", "1024" }, { "DSA", "SHA256withDSA", "1024" },
   * { "DSA", "SHA256withDSA", "2048" }, { "RSA", "SHA256withRSA", "1024" },
   * { "RSA", "SHA256withRSA", "2048" }, { "RSA", "SHA256withRSA", "3192" },
   * { "RSA", "SHA512withRSA", "1024" }, { "RSA", "SHA512withRSA", "2048" },
   * { "RSA", "SHA512withRSA", "3192" }, { "RSA", "MD5withRSA", "1024" },
   * { "RSA", "MD5withRSA", "2048" },
   * { "RSA", "MD5withRSA", "3192" }, { "EC", "SHA1withECDSA", "128" },
   * { "EC", "SHA1withECDSA", "256" },
   * { "EC", "SHA256withECDSA", "128" }, { "EC", "SHA256withECDSA", "256" },
   * { "EC", "SHA512withECDSA", "128" }, { "EC", "SHA512withECDSA", "256" },
   *
   * @param algorithm
   * @param bit
   * @return
   * @throws Exception
   */
  protected static KeyPair createKey(String algorithm, int bit) throws Exception {
    KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(algorithm);
    keyPairGenerator.initialize(bit);
    KeyPair keyPair = keyPairGenerator.generateKeyPair();
    return keyPair;
  }




  /**
   * 獲取公鑰
   *
   * @return
   * @throws Exception
   */
  public static String getPublicKey(String algorithm,int bit) throws Exception {
    if (Objects.isNull(keyPair)) {
      keyPair = createKey(algorithm,bit);
    }
    return ByteUtils.byteArr2HexStr(keyPair.getPublic().getEncoded());

  }

  /**
   * 獲取私鑰
   *
   * @return
   * @throws Exception
   */
  public static String getPrivateKey(String algorithm,int bit) throws Exception {
    if (Objects.isNull(keyPair)) {
      keyPair = createKey(algorithm,bit);
    }
    return ByteUtils.byteArr2HexStr(keyPair.getPrivate().getEncoded());

  }
  /**
   * 非對(duì)稱加密簽名
   * @param str
   * @param privateKey
   * @param algorithm
   * @param signAlgorithm
   * @return
   * @throws Exception
   */
  public static String sign(String str, String privateKey, String algorithm, String signAlgorithm) throws Exception {
    PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(ByteUtils.hexstr2ByteArr(privateKey));
    KeyFactory keyFactory = KeyFactory.getInstance(algorithm);
    PrivateKey dsaPrivateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
    Signature signature = Signature.getInstance(signAlgorithm);
    signature.initSign(dsaPrivateKey);
    signature.update(str.getBytes());
    return ByteUtils.byteArr2HexStr(signature.sign());
  }

  /**
   * 非對(duì)稱加密驗(yàn)證
   * @param sign
   * @param str
   * @param publicKey
   * @param algorithm
   * @param signAlgorithm
   * @return
   * @throws Exception
   */
  public static boolean verify(String sign, String str, String publicKey,String algorithm,String signAlgorithm) throws Exception {
    //base64編碼的公鑰
    X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(ByteUtils.hexstr2ByteArr(publicKey));
    KeyFactory keyFactory = KeyFactory.getInstance(algorithm);
    PublicKey dsaPublicKey = keyFactory.generatePublic(x509EncodedKeySpec);
    Signature signature = Signature.getInstance(signAlgorithm);
    signature.initVerify(dsaPublicKey);
    signature.update(str.getBytes());
    return signature.verify(ByteUtils.hexstr2ByteArr(sign));
  }
}