How to set 16 0's key value on TripleDESCryptoServiceProvider.

I want to set a known value for key in 3DES algorithm. But i have observed after using TripleDesCryptoServiceProvider in C# code and assigning all 16 0's as key my program gave error "Cryptographic Exception was unhandled"
     Please have a look on my piece of code,

   byte[] IV=new byte[8] {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00};
   byte[] key = new byte[24] { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00};

            TripleDESCryptoServiceProvider tDESalg = new TripleDESCryptoServiceProvider();

            // Create a string to encrypt.
            byte[] testData = new byte[8] { 0xD6,0x52,0xF9,0xCF,0x3F,0x31,0x7D,0xEC};


            tDESalg.IV = IV;
            tDESalg.Padding = PaddingMode.None;

            tDESalg.Key = key;    // Error Cryptographic Exception was unhandled. Specified key is a known weak key for 'TripleDES' and can't be used.

         How to solve this issue. I don't want to use default key value coming from TDES and as per my requirement key value must all zero.

1 Reply

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Vulpes15y ago
You can't solve it if the key you want to use is a 'weak key'. The TripleDESCryptoServiceProvider simply won't accept it and there's no way to trick it into doing so.

However, you could test other 'easy to remember' keys for weakness prior to use with the static TripleDES.IsWeakKey() method.

See http://msdn.microsoft.com/en-us/library/system.security.cryptography.tripledes.isweakkey.aspx
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