Twitter’s single access tokens work exactly the same way as basic auth, specifically for desktop applications which don’t necessarily require authentications by external users.
Instead of sending a username-password pair to the API, you now need a four-item set of consumer key, consumer secret and two access tokens to send to the API.
Full documentation: http://dev.twitter.com/pages/oauth_single_token
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Step-by-step guide:
1. Register your app on Twitter API
Go to http://dev.twitter.com/apps/new or dev.twitter.com > Your Apps > Register New App
Registrations are automatic, unlike whitelisting, so you get approved straight away. You don’t necessarily have to have an ‘app’, just a description of what you’ll be using the API for.
2. View your applications
Go to dev.twitter.com > Your Apps, which should display all your registered apps.
3. Get your key, secret and access tokens
On the same page, you should be able to see your Consumer Key and Consumer Secret.
On the right-hand side of the page, click on the button ‘My Access Token’. This would then generate your access token and access token secret.
Twitter advises you to keep all four items secret and not stored in plaintext.
4. Use all four items to access Twitter API
You now have to use all four items to authenticate your Twitter API requests. The way to do this varies according to your own clients. The http://dev.twitter.com/pages/oauth_single_token page has some useful examples of clients using C#, .NET, PHP, Python and Ruby. You’ll have to look elsewhere for Perl clients.
The basic idea of single access tokens is that instead of redirecting online users to Twitter for authentication, you bypass what they call the OAuth ‘dance’ by giving the API all four items it needs.