TripleDES: Specified key is a known weak key for &

Question

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.

For example:

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);
}

throws an exception

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

I know this is not a secure key. In production, the device will be flashed with a new, secure key. In the mean time, is there any way to inhibit this Exception from being thrown? Perhaps an app.config or registry setting?

Edit: 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.

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.

Answer 1

There is a great suggestion using reflection in the MSDN forums

Answer 2

I'm not a security expert but wouldn't XORing your key with another value be enough to satisfy the sanity check? You could do this for your debug version (with proper IFDEF) so you can do proper checking and remove it for your release or production version where the key would be strong enough.