package com.hzj.security;
import java.io.UnsupportedEncodingException;
import java.nio.charset.CharsetEncoder;
import java.security.KeyPair;
import com.hzj.util.StringHelper;
public class DataSecurity {
 private KeyPair keyPair;
 private static final String KEY_FILE = "/ca.key";
 private DataSignaturer dataSignaturer;
 public DataSecurity() {
 try {
 this.keyPair = KeyPairUtil.loadKeyPair(getClass().getResourceAsStream("/ca.key"));
 this.dataSignaturer = new DataSignaturer(this.keyPair.getPublic(), this.keyPair.getPrivate());
 } catch (RuntimeException e) {
 System.out.println("没有找到KeyPair文件[/ca.key]!");
 }
 }
 /**
 * 验证数字签名
 * @param data
 * @param signs
 * @return
 */
 public boolean verifySign(String data, String signs) {
 if ((data == null) || (signs == null)) {
 System.out.println("参数为Null");
 }
 boolean verifyOk = false;
 try {
 verifyOk = this.dataSignaturer.verifySign(data.getBytes("UTF-8"), StringHelper.decryptBASE64(signs));
 } catch (RuntimeException e) {
 System.out.println("fail!data=" + data + ", sign=" + signs + ", exception:" + e.getMessage());
 } catch (UnsupportedEncodingException e) {
 System.out.println("不支持UTF-8字符集");
 } catch (Exception e) {
 System.out.println("Exception:" + e.getMessage());
 }
 if (!verifyOk) {
 System.out.println("fail!data=" + data + ", sign=" + signs + ", verifyOk=false!");
 }
 return verifyOk;
 }
 /**
 * 生成数字签名
 * @param data
 * @return
 */
 public String sign(String data)
 {
 if (data == null) {
 System.out.println("参数为Null");
 }
 String sign = null;
 try
 {
 sign = StringHelper.encryptBASE64(this.dataSignaturer.sign(data.getBytes("UTF-8")));
 }
 catch (UnsupportedEncodingException e)
 {
 System.out.println("不支持UTF-8字符集");
 }
 catch (Exception e)
 {
 System.out.println(e.getMessage());
 }
 return sign;
 }
 }

package com.hzj.security;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.SignatureException;
public class DataSignaturer {
 private PrivateKey privateKey;
 private PublicKey publicKey;
 public DataSignaturer(PublicKey publicKey, PrivateKey privateKey){
 this.privateKey = privateKey;
 this.publicKey = publicKey;
 }
 /**
 * 进行数字签名
 * @param data
 * @return
 */
 public byte[] sign(byte[] data) {
 if (this.privateKey == null) {
 System.out.println("privateKey is null");
 return null;
 }
 Signature signer = null;
 try {
 signer = Signature.getInstance(this.privateKey.getAlgorithm());
 } catch (NoSuchAlgorithmException e) {
 System.out.println(e.getMessage());
 }
 try {
 signer.initSign(this.privateKey);
 } catch (InvalidKeyException e) {
 System.out.println(e.getMessage());
 }
 try {
 signer.update(data);
 return signer.sign();
 } catch (SignatureException e) {
 System.out.println(e.getMessage());
 return null;
 } catch (NullPointerException e) {
 System.out.println(e.getMessage());
 return null;
 }
 }
 /**
 * 验证数字签名
 * @param data
 * @param signature
 * @return
 */
 public boolean verifySign(byte[] data, byte[] signature) {
 if (this.publicKey == null) {
 System.out.println("publicKey is null");
 return false;
 }
 Signature signer = null;
 try {
 signer = Signature.getInstance(this.publicKey.getAlgorithm());
 } catch (NoSuchAlgorithmException e) {
 System.out.println(e.getMessage());
 return false;
 }
 try {
 signer.initVerify(this.publicKey);
 } catch (InvalidKeyException e) {
 System.out.println(e.getMessage());
 return false;
 }
 try {
 signer.update(data);
 return signer.verify(signature);
 } catch (SignatureException e) {
 System.out.println(e.getMessage());
 return false;
 }
 }
}

package com.hzj.security;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
public class KeyPairUtil {
 // 采用的双钥加密算法，既可以用DSA，也可以用RSA
 public static final String KEY_ALGORITHM = "DSA";
 /**
 * 从输入流中获取KeyPair对象
 * @param keyPairStream
 * @return
 */
 public static KeyPair loadKeyPair(InputStream keyPairStream) {
 if (keyPairStream == null) {
 System.out.println("指定的输入流=null!因此无法读取KeyPair!");
 return null;
 }
 try {
 ObjectInputStream ois = new ObjectInputStream(keyPairStream);
 KeyPair keyPair = (KeyPair) ois.readObject();
 ois.close();
 return keyPair;
 } catch (Exception e) {
 System.out.println(e.getMessage());
 }
 return null;
 }
 /**
 * 将整个KeyPair以对象形式存储在OutputStream流中， 当然也可以将PublicKey和PrivateKey作为两个对象分别存到两个OutputStream流中，
 * 从而私钥公钥分开，看需求而定。
 * @param keyPair 公钥私钥对对象
 * @param out 输出流
 * @return
 */
 public static boolean storeKeyPair(KeyPair keyPair, OutputStream out) {
 if ((keyPair == null) || (out == null)) {
 System.out.println("keyPair=" + keyPair + ", out=" + out);
 return false;
 }
 try {
 ObjectOutputStream oos = new ObjectOutputStream(out);
 oos.writeObject(keyPair);
 oos.close();
 return true;
 } catch (FileNotFoundException e) {
 System.out.println(e.getMessage());
 } catch (IOException e) {
 System.out.println(e.getMessage());
 }
 return false;
 }
 /**
 * 生成KeyPair公钥私钥对
 * 
 * @return
 */
 public static KeyPair initKeyPair() throws NoSuchAlgorithmException{
 KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
 keyPairGen.initialize(1024);
 return keyPairGen.genKeyPair();
 }
 /**
 * 生成密钥，并存储
 * @param out
 * @return
 * @throws NoSuchAlgorithmException
 */
 public static boolean initAndStoreKeyPair(OutputStream out) throws NoSuchAlgorithmException {
 return storeKeyPair(initKeyPair(), out);
 }
}

package com.hzj.util;
import sun.misc.BASE64Encoder;
import sun.misc.BASE64Decoder;
public class StringHelper {
 /** 
 * BASE64Encoder 加密 
 * @param data 要加密的数据 
 * @return 加密后的字符串 
 */ 
 public static String encryptBASE64(byte[] data) { 
 BASE64Encoder encoder = new BASE64Encoder(); 
 String encode = encoder.encode(data); 
 return encode; 
 } 
 /** 
 * BASE64Decoder 解密 
 * @param data 要解密的字符串 
 * @return 解密后的byte[] 
 * @throws Exception 
 */ 
 public static byte[] decryptBASE64(String data) throws Exception { 
 BASE64Decoder decoder = new BASE64Decoder(); 
 byte[] buffer = decoder.decodeBuffer(data); 
 return buffer; 
 } 
}

package com.hzj.main;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.security.NoSuchAlgorithmException;
import com.hzj.security.DataSecurity;
import com.hzj.security.KeyPairUtil;
public class Program {
 public static void main(String[] args) {
 // 1.生成证书
// File file = new File("ca.key");
// try {
// FileOutputStream fileOutputStream = new FileOutputStream(file);
// KeyPairUtil.initAndStoreKeyPair(fileOutputStream);
// } catch (FileNotFoundException | NoSuchAlgorithmException e) {
// e.printStackTrace();
// }
 // 2.生成数字签名
// DataSecurity dataSecurity = new DataSecurity();
// String sign = dataSecurity.sign("大家好");
// System.out.println("sign:" + sign);
 //3.验证数字签名
 DataSecurity dataSecurity = new DataSecurity();
 boolean result = dataSecurity.verifySign("大家好", "MCwCFCDs3sBw/fXK9flndl0M5lAUiPYFAhR9vyNNc91UiUBxFwK3GzLLjWgTkQ==");
 System.out.println("result：" + result);
 }
}