Obfuscate email?

Question

Let's start by saying I have a very large project, part of this project is to grab a user recovery action status, and a user email, and send it through a service layer back to the front end of the application. The catch is, the email needs to be altered on the back end so it doesn't get sent plain text. What I mean by this is, when the value gets populated on the back end, I need to have some code to modify it so it will have a format like this: j*****e@domain.com. This absolutely needs to be done in the method that I'm working on(which honestly isn't very big). Here is the method I have that will grab the status from another method within the same class, as well as grabbing the email of the user:

public CredentialRecoveryResponse RecoveryResponse(CredentialRecoveryRequest request)
    {
        CredentialRecoveryResponse response = new CredentialRecoveryResponse();
        response.Status = RecoverCredentials(request);
        if (response.Status == UserRecoveryActionStatus.Success)
        {
            User usr = UserRepository.GetByID(request.UserID);
            response.Email = usr.EmailAddress;
        }

        return response;
    }

Somehow, inside this method, I need to take that usr.EmailAddress and modify it do "block" or change the values to "*" for all characters except the first and last characters before the "@domain.com" portion. Is there a quick and easy way to do this within the method that way the whole email address isn't getting sent back through the wire?

Answer 1

Here's one take:

private static string ObfuscateEmail(string email)
{
     return Regex.Replace(email, "^(?<name>[^@]+)", m => {
          string match = m.Groups["name"].Value;
          return match[0] + new String('*', match.Length - 1);
     });
}

What is this doing?

1. The method uses Regex.Replace and passes a lambda function to do the actual replacement
2. The regex pattern simply says match everything to the left of the @ sign and create a named group called 'name'.
3. The lambda function then takes the first character of the match and appends to it a series of asterisks, using an overload of the String method (char, int) which repeats that char N number of times. It's N-1 here since the first char is unobfuscated.