TripleDES: Specified key is a known weak key for 'TripleDES' and cannot be used

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

Answer 1

The reflection based solutions get you around the problem, but they are dirty and evil. Nobody has yet mentioned a very useful method: TripleDES.IsWeakKey

I have had this problem and solved it with a very simple utility that I use immediately before I set the Key on my CryptoServiceProvider:

private void MakeSecureKey(byte[] key)
{
    while(TripleDES.IsWeakKey(key))
    {
        var sha = SHA256Managed.Create().ComputeHash(key);
        Array.Copy(sha,key,key.Length);
    }
}

If you call it anytime you make an encryptor or decryptor, it should prevent the crash and always give you a secure key.