Encrypting and Decrypting a token with a C# ASHX handler

Question

I've read a nice guide a few days ago about generating a token on the server's side to have the time of the token's creation within the token, along with "Guid.NewGuid()" 's encryption.

However, I've tried to adjust the results to have a user's username within the token, rather than the date time. I'm close, but I cannot extract the username itself, I can only receive it with some random letters after it.

Code of the ASP.NET generic handler to GENERATE the token upon identification

ASCIIEncoding encoder = new ASCIIEncoding();
if(postType == "identify")
{
        byte[] binName = encoder.GetBytes(name);
        byte[] key = Guid.NewGuid().ToByteArray();
        string _token = Convert.ToBase64String(binName.Concat(key).ToArray());
        // The above creates a token with the name and the "key", works well
}

Code of the generic handler to decrypt the token (see example for result)

if(postType == "check")
{
       string _token = dict["token"] as string;
        byte[] data = Convert.FromBase64String(_token);
        string theCode = encoder.GetString(data); // This will get both the username and the GUID key within
        context.Response.Write(jss.Serialize(new Code { eCode = theCode })); // Returns in JSON, irrelevant to the question, it works well
}

EXAMPLE: If the name would be "user", then the varialbe "theCode" would hold the value of "userXyZxYzXyZ" (while XyZ stands for the GUID's "random" key).

I think it is fair to say that my question is how to separate this GUID's key from the username upon decryption

Dont you just need to add some character in between them so you can then split them when you do your decryption like when you encrypt then add a | in between the name and the guid. — MoZahid, Jan 07 '14 at 17:07
@spender Yeah, thanks. I used the wrong term. My meaning was different. — Kfir Eichenblat, Jan 07 '14 at 18:35

score 2 · Accepted Answer · answered Jan 07 '14 at 17:15

2

A guid is 38 characters long, so the name will be theCode.SubString(0, theCode.Length - 38). Alternately, you can compare the current user's name with theCode: theCode.StartsWith(name).

answered Jan 07 '14 at 17:15

bmm6o

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Thanks. Didn't know about the length. – Kfir Eichenblat Jan 07 '14 at 17:59

Encrypting and Decrypting a token with a C# ASHX handler

1 Answers1