Encrypt using 3DES EDE / ECB / NOPadding

Question

I have received a task to encrypt and decrypt an XML string by using a TOKEN and a KEY. The encryption shall use 3DES EDE / ECB / NOPadding and can be made either in PHP or C#

I am not so prepared on this so I have read around a bit of theory and came to a very easy implementation which is as follow:

public string Encrypt( string message, string key, string token ) { byte[] toEncryptArray = UTF8Encoding.UTF8.GetBytes( message ); byte[] keyArray = CreateHash( key ); byte[] vectorArray = CreateHash( token ); TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider(); //set the secret key for the tripleDES algorithm tdes.Key = keyArray; //mode of operation. there are other 4 modes. We choose ECB(Electronic code Book) tdes.Mode = CipherMode.ECB; //padding mode(if any extra byte added) tdes.Padding = PaddingMode.None; ICryptoTransform cTransform = tdes.CreateEncryptor(keyArray, vectorArray); //transform the specified region of bytes array to resultArray byte[] resultArray = cTransform.TransformFinalBlock( toEncryptArray, 0, toEncryptArray.Length ); //Release resources held by TripleDes Encryptor tdes.Clear(); //Return the encrypted data into unreadable string format return Convert.ToBase64String( resultArray, 0, resultArray.Length ); } private byte[] CreateHash( string toHash ) { //use get hashcode regards to your key MD5CryptoServiceProvider hashKey = new MD5CryptoServiceProvider(); byte[] kArray = hashKey.ComputeHash( UTF8Encoding.UTF8.GetBytes( toHash ) ); //Always release the resources and flush data //of the Cryptographic service provide. Best Practice hashKey.Clear(); return kArray; }

However I think this is not completely correct. In fact I am not sure that the TOKEN shall be used this way. Can somebody provide more informations and point me to the right direction on how to solve this problem?

Thanks

@GregS: The TOKEN is a string of text which is 10 characters long. The task says to encrypt a message with 3DES/ECB/NOPadding by using a Key and a Token. The key is a string like "123456789012345678901234" (24 characters) — Lorenzo
– Lorenzo, Commented Jan 14, 2015 at 11:30

smiech · Accepted Answer · 2015-01-13 18:41:09Z

2

You could use token as a vector on TripleDESCryptoServiceProvider, together with the key.

ICryptoTransform cTransform = tdes.CreateEncryptor(key, token);

answered Jan 13, 2015 at 18:41

smiech

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2 Comments

Lorenzo Over a year ago

Thanks for your answer. I have edited my code by adding a new hash of the TOKEN and used as you've suggested. Did you meant that way?

smiech Over a year ago

Yes, I meant that way :)

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