我使用了.NET 3.0类 System.Security.Cryptography.MACTripleDES 类生成MAC值。不幸的是，我的工作与使用 1111111111111111 （十六进制）作为单长度DES密钥的硬件设备。钥匙上的 System.Security.Cryptography 图书馆里一些理智检查，并返回一个异常，如果您尝试使用加密的弱密钥。

I'm using the .NET 3.0 class System.Security.Cryptography.MACTripleDES class to generate a MAC value. Unfortunately, I am working with a hardware device that uses "1111111111111111" (as hex) as a single-length DES key. The System.Security.Cryptography library does some sanity checking on the key and returns a Exception if you try to use a cryptographically weak key.

例如：

byte[] key = new byte[24];
for (int i = 0; i < key.Length; i++)
  key[i] = 0x11;

byte[] data = new byte[] { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
byte[] computedMac = null;
using (MACTripleDES mac = new MACTripleDES(key))
{
  computedMac = mac.ComputeHash(data);
}

抛出一个异常

throws an exception

System.Security.Cryptography.CryptographicException : Specified key is a known weak key for 'TripleDES' and cannot be used.

我知道这是不是一个安全的关键。在生产中，该装置将被闪蒸以一个新的，安全的密钥。与此同时，有没有什么办法来抑制这种异常被抛出？也许一个的app.config 或注册表设置？

编辑：关键实际上是101010 ......由于算法迫使奇校验。我不知道这是否是普遍在支付处理的工作，我做了DES算法或只是一个必要条件。

The key would actually be 101010... due to the algorithm forcing odd parity. I'm not sure if this is universal to the DES algorithm or just a requirement in the payment processing work I do.

编辑2：下面丹尼尔的回答大约有黑客.NET一些非常好的信息。不幸的是，我无法使用这种技术来解决我的问题，但仍有一些有趣的阅读那里。

Edit 2: Daniel's answer below has some very good information about hacking .NET. Unfortunately, I wasn't able to solve my problem using this technique, but there is still some interesting reading there.

推荐答案

而不是使用MACTripleDES具有DES密钥重复假单DES CBC-MAC的，你可以只实现CBC-MAC自己在 DESCryptoServiceProvider 。

Instead of using MACTripleDES with the DES key repeated to fake a single DES CBC-MAC, you could just implement CBC-MAC yourself on top of DESCryptoServiceProvider.

＆LT; 1111111111111111>不是弱DES密钥

<1111111111111111> is not a weak DES key.

这将计算DES CBC-MAC：

This will calculate a DES CBC-MAC:

public static byte[] CalcDesMac(byte[] key, byte[] data){
    	DESCryptoServiceProvider des = new DESCryptoServiceProvider();
    	des.Key = key;
    	des.IV = new byte[8];
    	des.Padding = PaddingMode.Zeros;
    	MemoryStream ms = new MemoryStream();
    	using(CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write)){
    	  cs.Write(data, 0, data.Length);
    	}
    	byte[] encryption = ms.ToArray();
    	byte[] mac = new byte[8];
    	Array.Copy(encryption, encryption.Length-8, mac, 0, 8);
    	PrintByteArray(encryption);
    	return mac;
    }