In profile files data is stored in json format as describrd below:

1) Key "prf" contains json of name, email and password.
2) Key "con" contains usernames of contacts.
3) Key "conr" contains usernames of contacts whose request is still pending.
4) Key "grp" contains names of all groups of user.
5) Key "grpr" contains names of all groups whose request is still pending.
6) Key "lst" contains last seen date time value.

Refer dev.u for sample content.

Note: Instead of username userid can also be used if it fits your need.