使用C#中的Bouncy Castle加密/解密

Question

我使用"BouncyCastle.Crypto.dll"来加密/解密我的应用程序中的字符串.我正在使用此博客中的以下代码:

1. 我有一个BCEngine类,与上面提到的链接完全相同.

   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);
       }
   }
   

   }

我使用的是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);
      }
    }

不确定,但由于某种原因,我在调用btnEncrypt_Click时遇到异常

"密钥长度不是128/192/256位."

有人可以指导吗？我是一个完整的新手.提前致谢.

Answer 1

你string key = "DFGFRT";的不是128/192/256位.

DFGFRT 是6个字符,即6(或12？)字节= 8*12 = 96位(最多).

要获得一个128位的密钥,你需要一个16字节的字符串,所以我要安全地使用一个16字符的字符串,因此如果使用单字节字符则为128位密钥,如果使用宽字符则为256.

Answer 2

相当简单,你的密钥是"DFGFRT",它是6个字符/字节,即6*8 = 48位.

使用的加密方法需要长度为128/192/256位的密钥,等于16/24/32字符/字节.