validating Android's authToken on third party server

Question

I'm writing an Android application, which uses AccountManager to get the token. From an android app I'm able to interact with Google Picasa - it works fine.

What I would like to achieve is the following: send some text + authToken to my third party server, then check if the token is correct before saving the text. Now the question is: is it possible to determine if the authToken of a particular token is correct solely on the token itself (and maybe email address).

I've already programmed the server part, which accepts the token (send from android application), then issues a request to an URL address:

https://accounts.google.com/o/oauth2/tokeninfo?access_token=%token_here%

What I get back is the following JSON:

{
  "error" : "invalid_token"
}

But the link here http://oauthssodemo.appspot.com/step/4 states that if a token is correct I should receive a different JSON response. Can you tell me what I'm doing wrong: I believe that the way to check token's validity really isn't that simple, but I should rather implement the whole openid or something. Even if that is the case, how can I check whether the token send by android app is correct, so I can save the 'text' part of the message.

Thank you.

Answer 1

Stop using AccountManager and start using Google Play service’s GoogleAuthUtil class, then it gets easy. See http://android-developers.blogspot.ca/2013/01/verifying-back-end-calls-from-android.html

Answer 2

The solution is as follows. You can verify the token via this url:

https://accounts.google.com/o/oauth2/tokeninfo?access_token=%token_here%

But in my case I was trying to validate "Authorization code" and not "Access token" as you can see here: https://code.google.com/oauthplayground/

If you're using Android and OAuth don't use

lh2 

but rather use the following as service name:

http://picasaweb.google.com/data/

So you should call getAuthToken as follows

getAuthToken(account, "http://picasaweb.google.com/data/" , true, null, null);

Then you can validate the token received from this call on the URI posted above.