Use of the Facebook App Key Hash

Question

I have developed a sample app, which uses Facebook features, and it is working fine on my device(Samsung Galaxy S). For including Facebook features, i created a dev account(as r

Answer 1

It's just another security measure from facebook since it will allow your app to retrieve personal information. Sic, from www.facebook.com/developers :

A security key used for a more seamless login experience (e.g., snY1_9SPiOfe_xK2D-RT2ASFl5k).

This is specially important in mobile devices, since you may use it even without logging in: (SIC) From http://developers.facebook.com/docs/guides/mobile/#android_key_hash :

Single-Sign-On (SSO)

As with the iOS SDK, one of the most compelling features of the Android SDK is Single-Sign-On (SSO). SSO lets users sign into your app using their Facebook identity. If they are already signed into the Facebook Android app on their device they do not have to even type a username and password. Further, because they are signing to your app with their Facebook identity, you will have access to their profile information and social graph.