DES encryption weak key issue

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DES encryption weak key issue

Hello there,

I am facing an issue with my code (.net) when I try to encrypt data using key with all 0 it says ‘Specified key is a known weak key for ‘TripleDES’ and cannot be used.’ . with actual keys encryption is working fine. Can somebody help with this. Below is the code I use (c#)

TripleDES des = new TripleDESCryptoServiceProvider();
des.Key = key;
des.Mode = CipherMode.CBC;
des.IV = iv;
des.Padding = PaddingMode.None;
byte[] output = des.CreateEncryptor().TransformFinalBlock(data, 0, data.Length);

Thanks,

Aslam

Question is closed for new answers.
mohlam Selected answer as best April 27, 2021
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1 Answer

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Below code will help you with this. But may I know your use case for using weak keys? I hope only for testing purposes/initializing configuration etc. and recommend not to use it in your actual environment if you don’t have a specific use case with weak keys.

[apcode language=”csharp”]

TripleDES tripleDESalg = TripleDES.Create();
            TripleDESCryptoServiceProvider sm = tripleDESalg as TripleDESCryptoServiceProvider;
            sm.Padding = PaddingMode.None;
            sm.Mode = CipherMode.CBC;
            sm.IV = IV;
            MethodInfo mi = sm.GetType().GetMethod("_NewEncryptor", BindingFlags.NonPublic | BindingFlags.Instance);
            object[] Par = { Key, sm.Mode, EmptyIV, sm.FeedbackSize, 0 };
            ICryptoTransform trans = mi.Invoke(sm, Par) as ICryptoTransform;
             byte[] baOutData = SCUtility.ByteArrayToHexString(trans.TransformFinalBlock(data, 0, data.Length));

[/apcode]

You can find more information about weak keys here

admin Edited answer April 30, 2021
mohlam commented

Thanks. It worked. It is only for testing and not for the actual product
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