起因

首先，对于一个公司，即有.net又有java开发来说，加解密是需要相互打通的，因为，根据莫非定律你迟早会有“.net加密让java解密“的情况。

.net实现

public static string Encrypt(SymmetricAlgorithm algorithm, string plaintext, string key)
  {
      TripleDESCryptoServiceProvider tripleDes = new TripleDESCryptoServiceProvider();
      MD5CryptoServiceProvider hashMD5 = new MD5CryptoServiceProvider();
      algorithm.Key = hashMD5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(key));
      algorithm.Mode = CipherMode.ECB;
      Console.WriteLine("IV=" + Convert.ToBase64String(algorithm.IV));
      ICryptoTransform transformer = algorithm.CreateEncryptor();
      byte[] Buffer = ASCIIEncoding.ASCII.GetBytes(plaintext);
      byte[] result = transformer.TransformFinalBlock(Buffer, 0, Buffer.Length);
      return Convert.ToBase64String(result);
  }

.net和java的几个不同

1. byte类型对于.net是(0_{255)，而java来说它是有符号的，是(-128}127)
2. 对于DES来说，默认的java支持的密钥是8字节，而.net里algorithm.Key是16个字节，所以用原生Java的des是不能和.net互通的

java实现

需要第三方包bcprov-jdk15on

<dependency>
    <groupId>org.bouncycastle</groupId>
    <artifactId>bcprov-jdk15on</artifactId>
    <version>1.64</version>
    <scope>compile</scope>
</dependency>

实现与.net互通的加密过程

private static final String ALGORITHM = "DESede";
private static final String CIPHER_TRANSFER = "DESede/ECB/PKCS5Padding";
private static final String ENCODING = "UTF-8";
static {
         init();
}

public static void init() {
    BouncyCastleProvider bouncyCastleProvider = new BouncyCastleProvider();
    Security.addProvider(bouncyCastleProvider);
}
 /**
   * 初始化key.
   *
   * @param key
   */
  @SneakyThrows
  static SecretKey getSecretKey(String key) {
      MessageDigest md5 = MessageDigest.getInstance("MD5");
      byte[] bkeys = md5.digest(key.getBytes());
      SecretKey secretKey = new SecretKeySpec(bkeys, ALGORITHM);
      return secretKey;
  }

  /**
   * 字符串加密.
   *
   * @param plainText
   * @param key
   * @return
   * @throws Exception
   */
  @SneakyThrows
  public static String encryptToBase64(String plainText, String key) {
      SecretKey secretKey = getSecretKey(key);
      Cipher cipher = Cipher.getInstance(CIPHER_TRANSFER);
      cipher.init(Cipher.ENCRYPT_MODE, secretKey);
      byte[] result = cipher.doFinal(plainText.getBytes(ENCODING));
      String s1 = Base64.encodeBase64String(result);
      return s1;
  }

上面代码，主要是对于key的生成要注意，使用了与.net相同的md5对原始key进行的加密，保存它是16个字节。

原文链接:https://www.cnblogs.com/lori/p/14437994.html