JAVA 中解密RSA算法JS加密实例详解

JAVA 中解密RSA算法JS加密实例详解

有这样一个需求，前端登录的用户名密码，密码必需加密，但不可使用MD5，因为后台要检测密码的复杂度，那么在保证安全的前提下将密码传到后台呢，答案就是使用RSA非对称加密算法解决 。

java代码

需要依赖 commons-codec 包

RSACoder.Java

import org.apache.commons.codec.binary.Base64;

import javax.crypto.Cipher;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

/**
 * Created by lake on 17-4-12.
 */
public class RSACoder {
  public static final String KEY_ALGORITHM = "RSA";
  public static final String SIGNATURE_ALGORITHM = "MD5withRSA";

  private static final String PUBLIC_KEY = "RSAPublicKey";
  private static final String PRIVATE_KEY = "RSAPrivateKey";

  public static byte[] decryptBASE64(String key) {
    return Base64.decodeBase64(key);
  }

  public static String encryptBASE64(byte[] bytes) {
    return Base64.encodeBase64String(bytes);
  }

  /**
   * 用私钥对信息生成数字签名
   *
   * @param data    加密数据
   * @param privateKey 私钥
   * @return
   * @throws Exception
   */
  public static String sign(byte[] data, String privateKey) throws Exception {
    // 解密由base64编码的私钥
    byte[] keyBytes = decryptBASE64(privateKey);
    // 构造PKCS8EncodedKeySpec对象
    PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
    // KEY_ALGORITHM 指定的加密算法
    KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
    // 取私钥匙对象
    PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);
    // 用私钥对信息生成数字签名
    Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
    signature.initSign(priKey);
    signature.update(data);
    return encryptBASE64(signature.sign());
  }

  /**
   * 校验数字签名
   *
   * @param data   加密数据
   * @param publicKey 公钥
   * @param sign   数字签名
   * @return 校验成功返回true 失败返回false
   * @throws Exception
   */
  public static boolean verify(byte[] data, String publicKey, String sign)
      throws Exception {
    // 解密由base64编码的公钥
    byte[] keyBytes = decryptBASE64(publicKey);
    // 构造X509EncodedKeySpec对象
    X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
    // KEY_ALGORITHM 指定的加密算法
    KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
    // 取公钥匙对象
    PublicKey pubKey = keyFactory.generatePublic(keySpec);
    Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
    signature.initVerify(pubKey);
    signature.update(data);
    // 验证签名是否正常
    return signature.verify(decryptBASE64(sign));
  }

  public static byte[] decryptByPrivateKey(byte[] data, String key) throws Exception{
    // 对密钥解密
    byte[] keyBytes = decryptBASE64(key);
    // 取得私钥
    PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
    KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
    Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
    // 对数据解密
    Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
    cipher.init(Cipher.DECRYPT_MODE, privateKey);
    return cipher.doFinal(data);
  }

  /**
   * 解密<br>
   * 用私钥解密
   *
   * @param data
   * @param key
   * @return
   * @throws Exception
   */
  public static byte[] decryptByPrivateKey(String data, String key)
      throws Exception {
    return decryptByPrivateKey(decryptBASE64(data),key);
  }

  /**
   * 解密<br>
   * 用公钥解密
   *
   * @param data
   * @param key
   * @return
   * @throws Exception
   */
  public static byte[] decryptByPublicKey(byte[] data, String key)
      throws Exception {
    // 对密钥解密
    byte[] keyBytes = decryptBASE64(key);
    // 取得公钥
    X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
    KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
    Key publicKey = keyFactory.generatePublic(x509KeySpec);
    // 对数据解密
    Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
    cipher.init(Cipher.DECRYPT_MODE, publicKey);
    return cipher.doFinal(data);
  }

  /**
   * 加密<br>
   * 用公钥加密
   *
   * @param data
   * @param key
   * @return
   * @throws Exception
   */
  public static byte[] encryptByPublicKey(String data, String key)
      throws Exception {
    // 对公钥解密
    byte[] keyBytes = decryptBASE64(key);
    // 取得公钥
    X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
    KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
    Key publicKey = keyFactory.generatePublic(x509KeySpec);
    // 对数据加密
    Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
    cipher.init(Cipher.ENCRYPT_MODE, publicKey);
    return cipher.doFinal(data.getBytes());
  }

  /**
   * 加密<br>
   * 用私钥加密
   *
   * @param data
   * @param key
   * @return
   * @throws Exception
   */
  public static byte[] encryptByPrivateKey(byte[] data, String key)
      throws Exception {
    // 对密钥解密
    byte[] keyBytes = decryptBASE64(key);
    // 取得私钥
    PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
    KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
    Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
    // 对数据加密
    Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
    cipher.init(Cipher.ENCRYPT_MODE, privateKey);
    return cipher.doFinal(data);
  }

  /**
   * 取得私钥
   *
   * @param keyMap
   * @return
   * @throws Exception
   */
  public static String getPrivateKey(Map<String, Key> keyMap)
      throws Exception {
    Key key = (Key) keyMap.get(PRIVATE_KEY);
    return encryptBASE64(key.getEncoded());
  }

  /**
   * 取得公钥
   *
   * @param keyMap
   * @return
   * @throws Exception
   */
  public static String getPublicKey(Map<String, Key> keyMap)
      throws Exception {
    Key key = keyMap.get(PUBLIC_KEY);
    return encryptBASE64(key.getEncoded());
  }

  /**
   * 初始化密钥
   *
   * @return
   * @throws Exception
   */
  public static Map<String, Key> initKey() throws Exception {
    KeyPairGenerator keyPairGen = KeyPairGenerator
        .getInstance(KEY_ALGORITHM);
    keyPairGen.initialize(1024);
    KeyPair keyPair = keyPairGen.generateKeyPair();
    Map<String, Key> keyMap = new HashMap(2);
    keyMap.put(PUBLIC_KEY, keyPair.getPublic());// 公钥
    keyMap.put(PRIVATE_KEY, keyPair.getPrivate());// 私钥
    return keyMap;
  }
}

测试类

RSACoderTest.java

import org.junit.Before;
import org.junit.Test;

import java.security.Key;
import java.util.Map;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

/**
 * Created by lake on 17-4-12.
 */
public class RSACoderTest {
  private String publicKey;
  private String privateKey;

  @Before
  public void setUp() throws Exception {
    Map<String, Key> keyMap = RSACoder.initKey();
    publicKey = RSACoder.getPublicKey(keyMap);
    privateKey = RSACoder.getPrivateKey(keyMap);
    System.err.println("公钥: \n\r" + publicKey);
    System.err.println("私钥： \n\r" + privateKey);
  }

  @Test
  public void test() throws Exception {
    System.err.println("公钥加密——私钥解密");
    String inputStr = "abc";
    byte[] encodedData = RSACoder.encryptByPublicKey(inputStr, publicKey);
    byte[] decodedData = RSACoder.decryptByPrivateKey(encodedData,
        privateKey);
    String outputStr = new String(decodedData);
    System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);
    assertEquals(inputStr, outputStr);
  }

  @Test
  public void testSign() throws Exception {
    System.err.println("私钥加密——公钥解密");
    String inputStr = "sign";
    byte[] data = inputStr.getBytes();
    byte[] encodedData = RSACoder.encryptByPrivateKey(data, privateKey);
    byte[] decodedData = RSACoder.decryptByPublicKey(encodedData, publicKey);
    String outputStr = new String(decodedData);
    System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);
    assertEquals(inputStr, outputStr);
    System.err.println("私钥签名——公钥验证签名");
    // 产生签名
    String sign = RSACoder.sign(encodedData, privateKey);
    System.err.println("签名:" + sign);
    // 验证签名
    boolean status = RSACoder.verify(encodedData, publicKey, sign);
    System.err.println("状态:" + status);
    assertTrue(status);
  }
}

前端代码

依赖 jsencrypt 项目

<script src="bin/jsencrypt.min.js"></script>
<script type="text/javascript">
  var encrypt = new JSEncrypt();
  encrypt.setPublicKey('java生成的公钥');
  var encrypted = encrypt.encrypt('加密的字符串');
</script>

说明

前端生成加密的字符串encrypted，传到后台，java使用私钥进行解密即可。

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