David Freeman

David Freeman

Anti-Abuse Research Scientist & Engineering Leader
Principal Scientist, Delphi Research
dfreeman @ delphiresear . ch
LinkedIn Profile
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About Me

I am a data scientist / software engineer / security researcher with a Ph.D. in cryptography and a passion for using math and statistics to keep the Internet safe.

I spent 14 years building and leading teams at Meta and LinkedIn to address problems such as fake & compromised accounts; impersonation & identity verification; fraud, spam, & phishing; user data scraping; and measurement of all of the above.

I have published 27 research papers in cryptography and computer security and chaired international security workshops including Usenix Enigma, CCS AISec, and Fighting Abuse@Scale.

I currently live in the San Francisco Bay Area with my wife, two daughters, and five black cats.*

Consulting

I am available to advise on security-related projects. My areas of expertise include:

  • Risk assessment (e.g. quantifying attcker prevalence and intervention effectiveness)
  • Data science (e.g. signal collection and analysis for attack detection)
  • Data infrastructure (e.g. logging and data management for full-system visibility)
  • AI/Machine Learning (e.g. training, validation, deployment)
  • User-facing security features (e.g. authentication flows)
  • Research and technical writing (e.g. papers, talks)
  • Building security engineering teams (e.g. interviewing, onboarding, career development)

Contact me to discuss your project!

Resources

Here are some presentations that give an overview of my work:

  • My KISA 2026 talk looks at how AI will change the landscape of fighting internet abuse at scale.
  • My Enigma 2020 talk describes good and bad approaches to measuring abuse on the internet.
  • My ScAINet 2018 talk presents some of the challenges in using machine learning for security in the real world.
  • My Enigma 2016 talk shows some approaches to protecting accounts from being taken over.
  • My Strata 2015 talk gives an overview of the kinds of anti-abuse systems I work on.

In addition, my book on Machine Learning and Security contains everything I knew about the topic (as of late 2017).

Academic Background

I received my Ph.D. in Mathematics from the University of California, Berkeley. My Ph.D. advisors were Ken Ribet (UC Berkeley) and Ed Schaefer (Santa Clara University). Following my Ph.D., I was an NSF postdoctoral fellow at CWI, Amsterdam and Universiteit Leiden under the supervision of Ronald Cramer. I then spent three years as a postdoctoral scholar at Stanford under the supervision of Dan Boneh.

My thesis and postdoctoral research focused on cryptographic applications of number theory and arithmetic geometry. Projects included elliptic and hyperelliptic curve cryptography, pairing-based systems, and post-quantum cryptography.

My undergraduate degree is from Harvard (Chemistry and Physics and Mathematics) and I have a master's degree from Cambridge (Part III Maths).

* Technically four black cats and one gray cat, but we call the gray one "light black."

Books

Machine Learning and Security: Protecting Systems with Data and Algorithms Clarence Chio and David Freeman O'Reilly Media, 2018

Research at Meta

Research at LinkedIn

Research at Stanford and CWI

Research at UC Berkeley

Undergraduate Research

Other Papers

Anti-Abuse

Cryptography

Program Committee & Conference Service

Teaching

Since 2023 I've coached the Mathcounts team at Bullis Charter School in Los Altos, CA.

In Fall 2011 I taught Elliptic Curves in Cryptography (CS 259C/Math 250) at Stanford. Course web page.

In Fall 2007 I was a Graduate Student Instructor for Math 16a at Berkeley, taught by Jack Wagoner. Section web page.

In Fall 2005 I was a Graduate Student Instructor for Math 1a at Berkeley, taught by Vaughan Jones. Section web page.

Other Activities

Fact Tree Enterprises

  • ClassicalCDGuide.com — Recommends classical music CDs, with Top 10/20 lists and recommendations by composer, era, and genre. Reviews are extremely detailed. Great for a beginner or someone looking to expand their collection.
  • SailingCourseGuide.com — Provides general advice for anyone in the U.S. who wants to sign up for a sailing course, including tips on how to choose between schools and warning signs of problematic programs.

Travel Schedule

Last updated 20 Jul 2026

Contact Dr. Freeman

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