java - Java AES/CBC/PKCS5Padding 的 C# 加密/解密

Question

我在尝试解密已使用以下属性(Java 代码)在 Java 中加密的字符串时遇到问题

public static Builder getDefaultBuilder(String key, String salt, byte[] iv) {
        return new Builder()
                .setIv(iv)
                .setKey(key)
                .setSalt(salt)
                .setKeyLength(128)
                .setKeyAlgorithm("AES")
                .setCharsetName("UTF8")
                .setIterationCount(1)
                .setDigestAlgorithm("SHA1")
                .setBase64Mode(Base64.DEFAULT)
                .setAlgorithm("AES/CBC/PKCS5Padding")
                .setSecureRandomAlgorithm("SHA1PRNG")
                .setSecretKeyType("PBKDF2WithHmacSHA1");
    }

这是我到目前为止的代码(C#)

public string DecryptText(string encryptedString)
    {
        using (myRijndael = new RijndaelManaged())
        {
            myRijndael.Key = Convert.FromBase64String(encryptionKey);
            myRijndael.IV = new byte[16];
            myRijndael.Mode = CipherMode.CBC;
            myRijndael.Padding = PaddingMode.PKCS7;

            Byte[] ourEnc = Convert.FromBase64String(encryptedString);
            string ourDec = DecryptStringFromBytes(ourEnc, myRijndael.Key, myRijndael.IV);

            return ourDec;
        }
    }

protected string DecryptStringFromBytes(byte[] cipherText, byte[] Key, byte[] IV)
    {
        // Check arguments. 
        if (cipherText == null || cipherText.Length <= 0)
            throw new ArgumentNullException("cipherText");
        if (Key == null || Key.Length <= 0)
            throw new ArgumentNullException("Key");
        if (IV == null || IV.Length <= 0)
            throw new ArgumentNullException("Key");

        // Declare the string used to hold 
        // the decrypted text. 
        string plaintext = null;

        // Create an RijndaelManaged object 
        // with the specified key and IV. 
        using (RijndaelManaged rijAlg = new RijndaelManaged())
        {
            rijAlg.Key = Key;
            rijAlg.IV = IV;

            // Create a decrytor to perform the stream transform.
            ICryptoTransform decryptor = rijAlg.CreateDecryptor(rijAlg.Key, rijAlg.IV);

            // Create the streams used for decryption. 
            using (MemoryStream msDecrypt = new MemoryStream(cipherText))
            {
                using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                {
                    using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                    {

                        // Read the decrypted bytes from the decrypting stream 
                        // and place them in a string.
                        plaintext = srDecrypt.ReadToEnd();
                    }
                }
            }

        }

        return plaintext;

    }

但是当我尝试解密时，出现以下异常“System.Security.Cryptography.CryptographyException:'指定的 key 不是此算法的有效大小。'”。

Java代码的起源就在这里 https://github.com/simbiose/Encryption/blob/master/Encryption/main/se/simbio/encryption/Encryption.java

这是加密时的Java代码

public String encrypt(String data) throws UnsupportedEncodingException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidAlgorithmParameterException, InvalidKeyException, InvalidKeySpecException, BadPaddingException, IllegalBlockSizeException {
    if (data == null) return null;
    SecretKey secretKey = getSecretKey(hashTheKey(mBuilder.getKey()));
    byte[] dataBytes = data.getBytes(mBuilder.getCharsetName());
    Cipher cipher = Cipher.getInstance(mBuilder.getAlgorithm());
    cipher.init(Cipher.ENCRYPT_MODE, secretKey, mBuilder.getIvParameterSpec(), mBuilder.getSecureRandom());
    return Base64.encodeToString(cipher.doFinal(dataBytes), mBuilder.getBase64Mode());
}

private SecretKey getSecretKey(char[] key) throws NoSuchAlgorithmException, UnsupportedEncodingException, InvalidKeySpecException {
    SecretKeyFactory factory = SecretKeyFactory.getInstance(mBuilder.getSecretKeyType());
    KeySpec spec = new PBEKeySpec(key, mBuilder.getSalt().getBytes(mBuilder.getCharsetName()), mBuilder.getIterationCount(), mBuilder.getKeyLength());
    SecretKey tmp = factory.generateSecret(spec);
    return new SecretKeySpec(tmp.getEncoded(), mBuilder.getKeyAlgorithm());
}


private char[] hashTheKey(String key) throws UnsupportedEncodingException, NoSuchAlgorithmException {
    MessageDigest messageDigest = MessageDigest.getInstance(mBuilder.getDigestAlgorithm());
    messageDigest.update(key.getBytes(mBuilder.getCharsetName()));
    return Base64.encodeToString(messageDigest.digest(), Base64.NO_PADDING).toCharArray();
}

由于我并没有真正进行大量加密工作，因此我已经为此苦苦挣扎了两天，因此我们将不胜感激。

谢谢!

更新:全类

public sealed class MyCryptoClass
{
    protected RijndaelManaged myRijndael;

    private static string encryptionKey = "random";

    // Singleton pattern used here with ensured thread safety
    protected static readonly MyCryptoClass _instance = new MyCryptoClass();
    public static MyCryptoClass Instance
    {
        get { return _instance; }
    }

    public MyCryptoClass()
    {

    }

    public string DecryptText(string encryptedString)
    {
        using (myRijndael = new RijndaelManaged())
        {
            myRijndael.Key = Convert.FromBase64String(encryptionKey);
            myRijndael.IV = new byte[16];
            myRijndael.Mode = CipherMode.CBC;
            myRijndael.Padding = PaddingMode.PKCS7;

            Byte[] ourEnc = Convert.FromBase64String(encryptedString);
            string ourDec = DecryptStringFromBytes(ourEnc, myRijndael.Key, myRijndael.IV);

            return ourDec;
        }
    }


    public string EncryptText(string plainText)
    {
        using (myRijndael = new RijndaelManaged())
        {

            myRijndael.Key = HexStringToByte(encryptionKey);
            myRijndael.IV = HexStringToByte(initialisationVector);
            myRijndael.Mode = CipherMode.CBC;
            myRijndael.Padding = PaddingMode.PKCS7;

            byte[] encrypted = EncryptStringToBytes(plainText, myRijndael.Key, myRijndael.IV);
            string encString = Convert.ToBase64String(encrypted);

            return encString;
        }
    }


    protected byte[] EncryptStringToBytes(string plainText, byte[] Key, byte[] IV)
    {
        // Check arguments. 
        if (plainText == null || plainText.Length <= 0)
            throw new ArgumentNullException("plainText");
        if (Key == null || Key.Length <= 0)
            throw new ArgumentNullException("Key");
        if (IV == null || IV.Length <= 0)
            throw new ArgumentNullException("Key");
        byte[] encrypted;
        // Create an RijndaelManaged object 
        // with the specified key and IV. 
        using (RijndaelManaged rijAlg = new RijndaelManaged())
        {
            rijAlg.Key = Key;
            rijAlg.IV = IV;

            // Create a decrytor to perform the stream transform.
            ICryptoTransform encryptor = rijAlg.CreateEncryptor(rijAlg.Key, rijAlg.IV);

            // Create the streams used for encryption. 
            using (MemoryStream msEncrypt = new MemoryStream())
            {
                using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                {
                    using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                    {

                        //Write all data to the stream.
                        swEncrypt.Write(plainText);
                    }
                    encrypted = msEncrypt.ToArray();
                }
            }
        }


        // Return the encrypted bytes from the memory stream. 
        return encrypted;

    }

    protected string DecryptStringFromBytes(byte[] cipherText, byte[] Key, byte[] IV)
    {
        // Check arguments. 
        if (cipherText == null || cipherText.Length <= 0)
            throw new ArgumentNullException("cipherText");
        if (Key == null || Key.Length <= 0)
            throw new ArgumentNullException("Key");
        if (IV == null || IV.Length <= 0)
            throw new ArgumentNullException("Key");

        // Declare the string used to hold 
        // the decrypted text. 
        string plaintext = null;

        // Create an RijndaelManaged object 
        // with the specified key and IV. 
        using (RijndaelManaged rijAlg = new RijndaelManaged())
        {
            rijAlg.Key = Key;
            rijAlg.IV = IV;

            // Create a decrytor to perform the stream transform.
            ICryptoTransform decryptor = rijAlg.CreateDecryptor(rijAlg.Key, rijAlg.IV);

            // Create the streams used for decryption. 
            using (MemoryStream msDecrypt = new MemoryStream(cipherText))
            {
                using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                {
                    using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                    {

                        // Read the decrypted bytes from the decrypting stream 
                        // and place them in a string.
                        plaintext = srDecrypt.ReadToEnd();
                    }
                }
            }

        }

        return plaintext;

    }

    public static void GenerateKeyAndIV()
    {
        // This code is only here for an example
        RijndaelManaged myRijndaelManaged = new RijndaelManaged();
        myRijndaelManaged.Mode = CipherMode.CBC;
        myRijndaelManaged.Padding = PaddingMode.PKCS7;

        myRijndaelManaged.GenerateIV();
        myRijndaelManaged.GenerateKey();
        string newKey = ByteArrayToHexString(myRijndaelManaged.Key);
        string newinitVector = ByteArrayToHexString(myRijndaelManaged.IV);
    }

    protected static byte[] HexStringToByte(string hexString)
    {
        try
        {
            int bytesCount = (hexString.Length) / 2;
            byte[] bytes = new byte[bytesCount];
            for (int x = 0; x < bytesCount; ++x)
            {
                bytes[x] = Convert.ToByte(hexString.Substring(x * 2, 2), 16);
            }
            return bytes;
        }
        catch
        {
            throw;
        }
    }

    public static string ByteArrayToHexString(byte[] ba)
    {
        StringBuilder hex = new StringBuilder(ba.Length * 2);
        foreach (byte b in ba)
            hex.AppendFormat("{0:x2}", b);
        return hex.ToString();
    }
}

Answer 1

• 自从您的 MyCryptoClass.encryptionKey对应于您的Encryption.Builder.mKey您必须在 C# 端生成 key ，即您必须在 C# 端为此过程中涉及的每个 Java 方法实现一个对应项。这些 Java 方法是 getSecretKey(char[] key) , hashTheKey(String key)还有third.part.android.util.Base64.encodeToString(byte[] input, int flags) .

• 可能的 Java 方法的 C# 对应部分 getSecretKey(char[] key) :

  private static byte[] GetSecretKey()
  {
       string hashedKey = GetHashedKey();
       byte[] saltBytes = Encoding.UTF8.GetBytes(salt);                                                // builder.mCharsetName = "UTF8";
       int iterations = 1;                                                                             // builder.mIterationCount = 1
       byte[] secretKey = null;
       using (Rfc2898DeriveBytes rfc2898 = new Rfc2898DeriveBytes(hashedKey, saltBytes, iterations))   // builder.mSecretKeyType = "PBKDF2WithHmacSHA1";
       {
            secretKey = rfc2898.GetBytes(16);                                                          // builder.mKeyLength = 128;
            //Console.WriteLine("Key: " + ByteArrayToHexString(secretKey));
       }
       return secretKey;
   }
  

  此方法使用 PBKDF2WithHmacSHA1 派生 key 以 key 、盐、迭代次数和 key 长度作为输入。这里使用的 key (更准确地说是密码)是来自MyCryptoClass.encryptionKey的base64编码的SHA1哈希值。由GetHashedKey()提供(见下文)。

• 可能的 Java 方法的 C# 对应部分 hashTheKey(String key) :

  private static string GetHashedKey()
  {
       string hashBase64 = String.Empty;
       using (SHA1Managed sha1 = new SHA1Managed())                                  // builder.mDigestAlgorithm = "SHA1";
       {
            byte[] hash = sha1.ComputeHash(Encoding.UTF8.GetBytes(encryptionKey));   // builder.mCharsetName = "UTF8";
            hashBase64 = Base64ThirdPartAndroid(hash, true);
            //Console.WriteLine("Hash (base64): " + hashBase64);
       }
       return hashBase64;
   }
  

  此方法派生出 SHA1 -来自 MyCryptoClass.encryptionKey 的哈希值并对哈希值进行 Base64 编码。对于base64编码方法Base64ThirdPartAndroid(byte[] arr, bool withoutPadding) (见下文)被使用。

• 可能的 Java 方法的 C# 对应部分 third.part.android.util.Base64.encodeToString(byte[] input, int flags) ( https://github.com/simbiose/Encryption/blob/master/Encryption/main/third/part/android/util/Base64.java ):

  private static string Base64ThirdPartAndroid(byte[] arr, bool withoutPadding)
  {
       string base64String = System.Convert.ToBase64String(arr);
       if (withoutPadding) base64String = base64String.TrimEnd('='); // Remove trailing "="-characters
       base64String += "\n";                                         // Append LF (10)
       //Console.WriteLine("Array as base64 encoded string: " + base64String);
       return base64String;
  }
  

  在Java代码中third.part.android.util.Base64.encodeToString(byte[] input, int flags)与 flags = Base64.NO_PADDING 一起使用它删除了 base64 编码字符串末尾的“=”字符。另外还附加了换行符(LF，\n，ASCII 值:10)。如果使用的 Base64 编码不删除“=”字符或没有终止换行符，则解密将失败，因为散列是稍后生成的 key 的基础，该 key 必须在加密和解密时匹配解密端。据我所知，C# 端没有具有必要特征的 Base64 编码。但是，如果有这样的编码，您当然可以使用它。

• 将所有三个 C# 对应项添加到您的 MyCryptoClass class 中。

• 另外(到静态字段 encryptionKey )添加静态字段 initialisationVector , salt和secretKey给您MyCryptoClass -class 并分配以下值用于测试目的:

  private static string encryptionKey = "A7zb534OPq59gU7q";
  private static string salt = "JV5k9GoH";
  private static byte[] initialisationVector = Encoding.UTF8.GetBytes("l4iG63jN9Dcg6537");
  private static byte[] secretKey = GetSecretKey();
  

  参数的类型对应于Java代码中的类型(encryptionKey和salt是字符串，initialisationVector是字节数组)。 GetSecretKey()生成的 key 存储在字节数组 secretKey 中.

• 在你的 C# 中 DecryptText - 和EncryptText -方法集myRijndael.Key和myRijndael.IV至

  myRijndael.Key = secretKey;
  myRijndael.IV = initialisationVector;
  

• 按如下方式测试修改:

  • 使用您的 Java encrypt -方法加密以下纯文本:

    Test: The quick brown fox jumps over the lazy dog... 
    

    使用上面的 key/salt/iv

    mBuilder = Builder.getDefaultBuilder("A7zb534OPq59gU7q","JV5k9GoH","l4iG63jN9Dcg6537".getBytes("UTF-8"));
    

  • 加密后的文本为:

    mL4ajZtdRgD8CtGSfJGkT24Ebw4SrGUGKQI6bvBw1ziCO/J7SeLiyIw41zumTHMMD9GOYK+kR79CVcpoaHT9TQ==
    

  • 使用 C# 解密 DecryptText -方法再次给出纯文本。下面是两个测试用例:

    static void Main(string[] args)
    {
         // Test 1: Encrypted text from C#
         MyCryptoClass mcc = MyCryptoClass.Instance;
         string encryptedText = mcc.EncryptText("This is a plain text which needs to be encrypted...");
         Console.WriteLine("Encrypted text (base64): " + encryptedText);
         string decryptedText = mcc.DecryptText(encryptedText);
         Console.WriteLine("Decrypted text: " + decryptedText);
    
         // Test 2: Encrypted text from Java
         string javaEncryptedText = "mL4ajZtdRgD8CtGSfJGkT24Ebw4SrGUGKQI6bvBw1ziCO/J7SeLiyIw41zumTHMMD9GOYK+kR79CVcpoaHT9TQ==";
         Console.WriteLine("Encrypted text from Java (base64): " + javaEncryptedText);
         string javaDecryptedText = mcc.DecryptText(javaEncryptedText);
         Console.WriteLine("Decrypted text from Java: " + javaDecryptedText);
    }