What the FLoC?

Michael Oehler
Research Affiliate
UMBC Cyber Defense Lab

Friday, November 19, 2021
Remotely via WebEx: umbc.webex.com/meet/sherman

Recording of Talk.


Federated Learning of Cohorts (FLoC) is a proposed web tracking mechanism from Google, and part of Google’s Privacy Sandbox initiative to deprecate 3rd-party cookies. Instead of cookies, FLoC places a user’s interests into a “cohort.” The cohort acts as an identification label that is sent to a web server. The server uses the cohort (a label) to return targeted advertisements. Privacy concerns with FloC abound. If the number of users in a cohort is too small, specific persons could be identified. If the number of cohorts is too large, a targeted group could be identified. Retribution towards specific persons or types of people may be possible. Thus, there are concerns for people in politically oppressed countries, advocating prejudicial bias, and other possible privacy concerns. The Electronic Frontier Foundation (EFF) states “FLoC is a terrible idea” [1]. Several browser manufactures have refuted FLoC [2]. Today’s presentation will review 3rd-party cookies, and introduce FLoC and SimHash to estimate set similarity. The underlying privacy concerns is the driving focus of the presentation

[1] Bennett Cyphers, Electronic Frontier Foundation (EFF), “Google’s FLoC Is a Terrible Idea,” March 3, 2021.

[2] Dieter Bohn, The Verge, “Nobody is flying to FLoC – Brave, Vivaldi, Edge, and Mozilla are all out,” April 16, 2021.

About the Speaker:

Dr. Michael Oehler is a career civilian, a PhD graduate from UMBC’s Cyber Defense Laboratory (CDL), and cybersecurity expert. His career spans three decades and roles as varied as a threat reporter, technical director for endpoint security, and visiting professor to the US Naval Academy. His interests include applied cryptography, security protocols, operating system security, and pinball. Email: oehler@gmail.com


Alan T. Sherman, sherman@umbc.edu

Upcoming CDL Meetings:

Dec 3, Sherman-Gomez-Bonyadi-Golaszewski, Shadow IT in Higher Ed

Feb 4, Filipo Sharevski


Support for this event was provided in part by the National Science Foundation under SFS grant DGE-1753681.

The UMBC Cyber Defense Lab meets biweekly Fridays 12-1pm. All meetings are open to the public.