Facebook API - uids and email

Question

I am trying to develop an application in which

• User "X" has signed up for Facebook
• the application has a set of email addresses (possible friends of user "X")
• app gets 'X' friends list (uids)
• Want to check if the user with the email address [e-mail] is really a facebook user using the email address and is an X-friend (mainly for matching email addresses).

Answer 1

, . UID . FQL, email_hash :

SELECT email_hashes FROM user WHERE uid IN (comma_delimted_set_of_uids)

, facebook email_hash. , . FB, - crc32 md5 (_).

Answer 2

, oAuth, FB api, , , .