How can I securely check if a username is already taken?

Posted by Geo on Stack Overflow See other posts from Stack Overflow or by Geo
Published on 2010-05-29T14:34:25Z Indexed on 2010/05/29 14:42 UTC
Read the original article Hit count: 193

Filed under:

AJAX

|

security

|

web

|

user-registration

I have a form where someone can create a new user. I'd like to add some AJAX to check if a username is taken, as soon as the input field loses focus. I'm not really sure how to go about this, as this could pave the way to bruteforce attack, since you could check for any username and see whether or not it exists. Any suggestions?

© Stack Overflow or respective owner

Related posts about AJAX

Ajax call from a form rendered as Ajax response (jQuery + Grails: chaining ajax requests)

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello, I was expecting the below scenario common, but couldn't find much help online. I have a form loaded through Ajax (say, create entity form). It is loaded through a button click (load) event $("#bt-create").click(function(){ $ ('#pid').load('/controller/vehicleModel/create3'); … >>> More
Ajax Control Toolkit Now Supports jQuery

as seen on Stephen Walter - Search for 'Stephen Walter'
I’m excited to announce the September 2013 release of the Ajax Control Toolkit, which now supports building new Ajax Control Toolkit controls with jQuery. You can download the latest release of the Ajax Control Toolkit from http://AjaxControlToolkit.CodePlex.com or you can install the Ajax Control… >>> More
The Microsoft Ajax Library and Visual Studio Beta 2

as seen on Stephen Walter - Search for 'Stephen Walter'
Visual Studio 2010 Beta 2 was released this week and one of the first things that I hope you notice is that it no longer contains the latest version of ASP.NET AJAX. What happened? Where did AJAX go? Just like Sting and The Police, just like Phil Collins and Genesis, just like Greg Page and the Wiggles… >>> More
Video Aulas gratuitas de ASP.NET AJAX

as seen on ASP.net Weblogs - Search for 'ASP.net Weblogs'
Olá pessoal, A Microsoft publicou 14 vídeos que cedi a eles a respeito do ASP.NET AJAX. Todos os vídeos são gratuitos, e caso você ainda use o AJAX estas lições podem ajudá-lo bastante. Tenha um excelente estudo. Instalação do AJAX Control Tookit ASP.NET AJAX: Controle calendário ASP.NET… >>> More
July 2013 Release of the Ajax Control Toolkit

as seen on Stephen Walter - Search for 'Stephen Walter'
I’m super excited to announce the July 2013 release of the Ajax Control Toolkit. You can download the new version of the Ajax Control Toolkit from CodePlex (http://ajaxControlToolkit.CodePlex.com) or install the Ajax Control Toolkit from NuGet: With this release, we have completely rewritten the… >>> More

Related posts about security

sudo apt-get update errors

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
Here is what I get on my terminal when running sudo apt-get update errors. I dont know if the issue is from my sources.list or my proxy setup(have not made any changes to proxies). Thank you for any help in advanced. Ign http://security.ubuntu.com oneiric-security Release.gpg Ign http://security… >>> More
The Security-Developer Gap: Why IT Security Can't Fix Your Security Problems Alone

as seen on Devx - Search for 'Devx'
Two well-known white hats explain how hackers take advantage of security holes left by enterprise application developers. >>> More
The Security-Developer Gap: Why IT Security Can't Fix Your Security Problems Alone

as seen on Internet.com - Search for 'Internet.com'
Two well-known white hats explain how hackers take advantage of security holes left by enterprise application developers. >>> More
StackOverFlowError while creating Mac object on AS400/Java

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello all, I am a newbie to AS400-Java programming. I am trying to create my first program to test the implementation of Message Authentication Code (MAC). I am trying to use the HMACSHA1 hash function. My (Java 1.4) program runs fine on a dev box (V5R4).But fails terribly on the QA box (V5R3). My… >>> More
Google App Engine - Spring Security Issue (java.security.AccessControlException)

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm currently getting the AccessControlException below when I deploy to app engine (I don't see it when I run in my local environment). I'm using GAE 1.3.1, Spring 3.0.1, and Spring Security 3.0.2. Any ideas how to get around this issue? It appears to be an issue with Spring Security trying to get… >>> More