I'm implementing a Log In With Facebook button on my website, and will be using the email field for two purposes:
create a new account if I don't have this email in my user database
match an existing account if I have a user with this email address
Does Facebook guarantee that they verified the user owns this email address when they return the field in their API?
Otherwise, in the (unlikely) event that a user of my website does not have a Facebook account, someone could create a Facebook account with this email, without validating it, to log in to my website with their account.
They are supposed to be but Facebook has had issues in the past of unverified emails being allowed to pass through the API Is it possible to check if an email is confirmed on Facebook?.
If you implicitly allow Facebook accounts to link up via email, then the next time Facebook has an issue they can effectively take control of all your users accounts.
The secure way to link users up is to either:
Ask a normal user to link their facebook account by logging into it.
Ask a Facebook-user to login with your sites normal account.
Related
I'd like to offer our users a Facebook login option. But I'm not sure how to identify existing users (without a stored Facebook ID).
From the docs:
https://developers.facebook.com/docs/facebook-login/multiple-providers#addingfacebook
After a successful login using Facebook, you will have the person's
email address, Facebook ID, and access token. Your app should search
for an existing account that has been created with that same email
address. If one exists, you should merge the two accounts and add
the Facebook info to the existing account - as recommended above.
That doesn't sound like a secure approach to me. What would prevent someone from creating a new Facebook account with a fake email address that matches a user account in my app and then use my Facebook login option? (Obviously, this will not work if the user already owns a Facebook account)
Your concern...
That doesn't sound like a secure approach to me. What would prevent someone from creating a new Facebook account with a fake email address that matches a user account in my app and then use my Facebook login option? (Obviously, this will not work if the user already owns a Facebook account)
TL;DR
Facebook Registration process
Go to facebook.com/reg.
Enter the name you go by in everyday life.
Enter your email or mobile phone number.
So...
Facebook needs your email or phone number, that means there's no way someone can use another account's email or phone number to sign up again.
My advice to you is...
You have two or more authentication methods - 1 manual (email & pass) | the rest (social login).
You already have users, so when users login using OAuth and a matching email or phone number is found, you ask permission to link their Facebook account to your app or site account with a matching credential.
At this point you should authenticate the persons identity one last time, by having them enter the password for their account on your app or site.
Now you can safely assume this person is who they say they are and store their info in your DB.
My application allows for user authentication via Facebook. I am calling FB Graph API to get details on a logged in user like so...
https://graph.facebook.com/<fbUserId>
But sometimes I see that email address is not one of the fields which is returned. I think this is because when the user was prompted to allow my app access to their public profile and email address, the user chose not to provide their email address. However my application needs email addresses. Is there any way I can tell FB through the Graph API to make that "Edit the info you provide" dialog to reappear so the user can subsequently choose to give their email address?
I think you're asking about how to re-prompt users who denied a permission, so that they're asked to grant the already-declined permission?
If so, you can check which permissions were granted and then re-prompt for those which were previously declined - as you noted, users aren't prompted multiple times to accept a permission if they've already declined it
To re-request, use auth_type: rerequest in your call to FB.Login() (javascript) or your call to the Login dialog; I believe the mobile SDKs handle this automatically (e.g. FBSDKLoginManager in the IOS SDK)
Note that with your specific example, it's possible a user won't have an email address accessible via the API even if they do grant you the email permission, as they may have an unreachable address, be a user without a confirmed address, have signed up to Facebook using a mobile phone number, etc
As a result, you may need to build a UI for users to manually supply their email address anyway, if that info is truly necessary for your app
A site I'm working for is having significant problems with fake users through facebook openID. Is there an API call which reports on the internal facebook calculations of the "humanness" of a user and/or indications that the account has been compromised?
If there were internal Facebook calculations of the "humanness" of a user, then there wouldn't fake users using openId to your client's website. Facebook would have already removed them.
You can check the verified field of the user Graph API object.
A user is considered verified if she takes any of the following
actions:
Registers for mobile
Confirms her account via SMS
Enters a valid credit card
You may want to play politics like some sites have done saying, you need X nbr of friends, have a profile pic, etc.
I'm developing a website where the user can either sign up creating his own profile or can sign in with FB or Twitter.
The thing is I don't really know how to manage it, for example: let's say my user signs up through the website and creates content, what happens if the user later decides to sign in with FB or Twitter? How can I keep it all unified?
I know I could just do the Twitter sign in, get the data from twitter and create a profile in my DB for the user with his Twitter handle, don't know how I'd deal with later if he wants to just log in through the site.
Anyone have any ideas?
So he later signs in with Twitter or Facebook. I think you have a couple of options in this case. Allow the ability to link accounts together once the user signs in with any one method. Say they sign in with your sites registration, let them hit a page where they can add in other linked accounts like Twitter and Facebook once they are in their logged in state on your site. See the friendfeed model for inspiration. Or, like we did with ucubd.com/index.aspx - let the user sign in with facebook and regsister an account on their behalf and ask for their email as the login credential. If it's found - great. If it's not ask for a password. This will allow the user to either login with your sites registration method or through facebook. You will have the information in your database to link both of them together.
Every account on your system will have an e-mail address. Every account with FB, Google, Twitter is also linked to an e-mail address. What you will need to do is link the accounts based on e-mail address. That way you will never get duplicate accounts.
HI, I hava a website in php where i have integrated a Facebook Connect API which enabled the Facebook login button.
I login using the button by providing my Facebook credentials. It gets logged in. I can access my profile picture, full name and some other information. But i can't access the user email id i.e. the Facebook user id. I have checked the FBML page here but i didn't get any tag that may give me the user id. I guess that Facebook might not allow me to get the id.
Please help me how to get the Facebook user id from the Facabook Connect API.
Apparently, Facebook uses an numeric increment ID instead of email addresses to uniquely identify each User entity. By Facebook API policies, email addresses are protected to prevent spam and other issues.
In order for an application to get the email addresses of a Facebook User, you will need special permissions from the User. See the API for such permissions.