A system including: one or more processors; a memory storing instructions that, when executed by the one or more processors are configured to cause the system to: receive a plurality of user names and a plurality of anonymized user identifiers; receive a plurality of user attributes associated with one or more users of the plurality of users; receive a first plurality of hash values that uniquely identify an association between each user attribute and one or more users; receive a first request for a listing of user names associated with a first user attribute; receive a first secret key; generate a second plurality of hash values; determine a first subset of the first plurality of hash values that match the second plurality of hash values; generate a first graphical user interface including the listing of user names; and transmit the first graphical user interface to the first user device.