使用Bouncy Castle在C#中进行加密/解密

Question

使用Bouncy Castle在C#中进行加密/解密

20

我在我的应用程序中使用"BouncyCastle.Crypto.dll"来加密/解密字符串。我正在使用此博客的代码：

我有一个名为BCEngine的类，与上面提到的链接中给出的完全相同。

public class BCEngine
{
   private readonly Encoding _encoding;
   private readonly IBlockCipher _blockCipher;
   private PaddedBufferedBlockCipher _cipher;
   private IBlockCipherPadding _padding;

   public BCEngine(IBlockCipher blockCipher, Encoding encoding)
   {
      _blockCipher = blockCipher;
      _encoding = encoding;
   }

   public void SetPadding(IBlockCipherPadding padding)
   {
       if (padding != null)
         _padding = padding;
   }

   public string Encrypt(string plain, string key)
   {
       byte[] result = BouncyCastleCrypto(true, _encoding.GetBytes(plain), key);
       return Convert.ToBase64String(result);
   }

   public string Decrypt(string cipher, string key)
   {
      byte[] result = BouncyCastleCrypto(false, Convert.FromBase64String(cipher), key);
      return _encoding.GetString(result);
   }

   /// <summary>
   ///
   /// </summary>
   /// <param name="forEncrypt"></param>
   /// <param name="input"></param>
   /// <param name="key"></param>
   /// <returns></returns>
   /// <exception cref="CryptoException"></exception>
   private byte[] BouncyCastleCrypto(bool forEncrypt, byte[] input, string key)
   {
       try
       {
           _cipher = _padding == null ? new PaddedBufferedBlockCipher(_blockCipher) : new PaddedBufferedBlockCipher(_blockCipher, _padding);
           byte[] keyByte = _encoding.GetBytes(key);
           _cipher.Init(forEncrypt, new KeyParameter(keyByte));
           return _cipher.DoFinal(input);
       }
       catch (Org.BouncyCastle.Crypto.CryptoException ex)
       {
           throw new CryptoException(ex.Message);
       }
   }
}

我正在使用一个asp.net表单，其中我编写了如下代码：

    public partial class EncryptionForm : System.Web.UI.Page
    {
      Encoding _encoding;
      IBlockCipherPadding _padding;
      string key = "DFGFRT";
       string textToBeEncrypted = "Original text. Please encrypt me.";
       string txtEncryptedText = string.empty;
       string txtDecryptedText = string.empty;

      protected void Page_Load(object sender, EventArgs e)
      {
          _encoding = Encoding.ASCII; 
          Pkcs7Padding pkcs = new Pkcs7Padding();
          _padding = pkcs;   
      }

      protected void btnEncrypt_Click(object sender, EventArgs e)
      {
          txtEncryptedText = AESEncryption(textToBeEncrypted, key, true);
      }

      protected void btnDecrypt_Click(object sender, EventArgs e)
      {
          txtDecryptedText = AESDecryption(txtEncryptedText.Text, key, true);
      }

      public string AESEncryption(string plain, string key, bool fips)
      {
          BCEngine bcEngine = new BCEngine(new AesEngine(), _encoding);
          bcEngine.SetPadding(_padding);
          return bcEngine.Encrypt(plain, key);
      }

      public string AESDecryption(string cipher, string key, bool fips)
      {
          BCEngine bcEngine = new BCEngine(new AesEngine(), _encoding);
          bcEngine.SetPadding(_padding);
          return bcEngine.Decrypt(cipher, key);
      }
    }

我不确定，但出于某种原因，当我调用btnEncrypt_Click时会抛出异常：

"密钥长度不是 128/192/256 比特。"

请问有人可以指导一下吗？我完全是新手，谢谢。

- Hari

嗨Hari，我也在用C#开发我的Android应用程序中的PGP消息传递功能。希望你能帮我解决一个问题。我们可以联系一下吗？ - Yaza

3个回答

5

很简单，您的密钥是“DFGFRT”，它由6个字符/字节组成，即6 * 8 = 48位。

所使用的加密方法需要一个长度为128/192/256位的密钥，这相当于16/24/32个字符/字节。

- Roger Far

@jgauffin，你是编辑了我的回答还是Rogier21s的？我在我的回答里做了一个编辑，他在评论中说你编辑过它。 - Matt

我都编辑过了。你的需要更易读，他的需要将字节改为位。 - jgauffin

0

公共类AesGcm256 { private static readonly SecureRandom Random = new SecureRandom(); }

    // Pre-configured Encryption Parameters
    public static readonly int NonceBitSize = 128;
    public static readonly int MacBitSize = 128;
    public static readonly int KeyBitSize = 256;

    private AesGcm256() { }

    public static byte[] NewKey()
    {
        var key = new byte[KeyBitSize / 8];
        Random.NextBytes(key);
        return key;
    }

    public static byte[] NewIv()
    {
        var iv = new byte[NonceBitSize / 8];
        Random.NextBytes(iv);
        return iv;
    }

    public static Byte[] HexToByte(string hexStr)
    {
        byte[] bArray = new byte[hexStr.Length / 2];
        for (int i = 0; i < (hexStr.Length / 2); i++)
        {
            byte firstNibble = Byte.Parse(hexStr.Substring((2 * i), 1), System.Globalization.NumberStyles.HexNumber); // [x,y)
            byte secondNibble = Byte.Parse(hexStr.Substring((2 * i) + 1, 1), System.Globalization.NumberStyles.HexNumber);
            int finalByte = (secondNibble) | (firstNibble << 4); // bit-operations only with numbers, not bytes.
            bArray[i] = (byte)finalByte;
        }
        return bArray;
    }


    public static string toHex(byte[] data)
    {
        string hex = string.Empty;
        foreach (byte c in data)
        {
            hex += c.ToString("X2");
        }
        return hex;
    }


    public static string toHex(string asciiString)
    {
        string hex = string.Empty;
        foreach (char c in asciiString)
        {
            int tmp = c;
            hex += string.Format("{0:x2}", System.Convert.ToUInt32(tmp.ToString()));
        }
        return hex;
    }

    public static string encrypt(string PlainText, byte[] key, byte[] iv)
    {
        string sR = string.Empty;
        try
        {
            byte[] plainBytes = Encoding.UTF8.GetBytes(PlainText);

            GcmBlockCipher cipher = new GcmBlockCipher(new AesFastEngine());
            AeadParameters parameters = new AeadParameters(new KeyParameter(key), 128, iv, null);

            cipher.Init(true, parameters);

            byte[] encryptedBytes = new byte[cipher.GetOutputSize(plainBytes.Length)];
            Int32 retLen = cipher.ProcessBytes(plainBytes, 0, plainBytes.Length, encryptedBytes, 0);
            cipher.DoFinal(encryptedBytes, retLen);
            sR = Convert.ToBase64String(encryptedBytes, Base64FormattingOptions.None);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
            Console.WriteLine(ex.StackTrace);
        }

        return sR;
    }


    public static string decrypt(string EncryptedText, byte[] key, byte[] iv)
    {
        string sR = string.Empty;
        try
        {
            byte[] encryptedBytes = Convert.FromBase64String(EncryptedText);

            GcmBlockCipher cipher = new GcmBlockCipher(new AesFastEngine());
            AeadParameters parameters = new AeadParameters(new KeyParameter(key), 128, iv, null);
            //ParametersWithIV parameters = new ParametersWithIV(new KeyParameter(key), iv);

            cipher.Init(false, parameters);
            byte[] plainBytes = new byte[cipher.GetOutputSize(encryptedBytes.Length)];
            Int32 retLen = cipher.ProcessBytes(encryptedBytes, 0, encryptedBytes.Length, plainBytes, 0);
            cipher.DoFinal(plainBytes, retLen);

            sR = Encoding.UTF8.GetString(plainBytes).TrimEnd("\r\n\0".ToCharArray());
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
            Console.WriteLine(ex.StackTrace);
        }

        return sR;
    }

}

- Lokesh Polineni

1

目前你的回答不够清晰，请编辑并添加更多细节，以帮助其他人理解它如何回答问题。你可以在帮助中心找到有关如何撰写好答案的更多信息。 - Community

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- Matt · Accepted Answer

你的string key = "DFGFRT";长度不足128/192/256位。

DFGFRT只有6个字符，相当于6（或12？）个字节=8*12 = 96位（最多）。

如果想获得128位密钥，你需要使用一个16字节的字符串，因此我建议使用长度为16的字符串，这样如果使用单字节字符，则会生成128位密钥，如果使用宽字符，则会生成256位密钥。