Bio

I'm a Research Professor in BU computer science focusing on privacy. I also am a Civic Tech Fellow at the Faculty of Computing and Data Sciences at BU and have an affiliation with BU's Hariri Institute. I got my PhD from Johns Hopkins University in 2020, under the supervision of my advisors Avi Rubin and Matt Green. I am an observant Jew, which may affect when I can respond to your emails. A copy of my CV is available here.

If you came to this website expecting stuff about the placebo effect or alternative medicine, you may be looking for my father's website.

I'm going to be starting a tenure track position at the University of Maryland, College Park in Fall 2024. If you are interested in working with me as a PhD student, take a look at this blog post!

An Occasional Blog

I have started an occasional blog here. My latest post is some thoughts about common mistakes I've noticed recently while reviewing for security and crypto conferences. My hope is that it can be helpful to students writing papers for these venues.

MPC FAQ

I have compiled an FAQ about secure multiparty computation (MPC) aimed at non-experts. The FAQ can be found here. If you notice some way in which it can be improved, please send me an email!

2024 Updates

  •   I'm going to be giving an invited talk at CFAIL, expanding on my recent RWC talk on deploying MPC!
  •   Our Talk "Analyzing Cryptography in Context: The Case Study of Apple's CSAM Scanning Proposal" accepted at CAW24 (Affilited with Eurocrypt 2024)!
  •   We submitted a comment on NIST SP 800-226: Guidelines for Evaluating Differential Privacy Guarantees. You can read our comment here.
  •   Two papers about which I was particularly excited, Dora and Pulsar, both rejected from USENIX Security
  •   Our paper on tracing the origin of viral messages is E2E systems was rejected from Eurocrypt 2024
  •   Our Talk "The Good, The Bad, and The Ugly — Lessons from an MPC for Social Good Deployment" accepted at RWC24! Unfortunetly, our other talk submission was rejected.

Teaching

Preprints

  • Pulsar: Secure Steganography through Diffusion Models.*
      Tushar M. Jois, Gabrielle Beck, and Gabriel Kaptchuk. [eprint PDF]
  • Dora: Processor Expressiveness is (Nearly) Free in Zero-Knowledge for RAM Programs.
      Aarushi Goel, Mathias Hall-Andersen, and Gabriel Kaptchuk. [eprint PDF]

Publications

(Authors alphabetical by default. Publications ordered by contribution marked with *)
  • Safer Digital Intimacy for Sex Workers and Beyond: A Technical Research Agenda.
      Vaughn Hamilton, Gabriel Kaptchuk, Allison McDonald, and Elissa M. Redmiles. [PDF] [Local Copy]
      IEEE Security and Privacy Magazine
  • SocIoTy: Practical Cryptography in Smart Home Contexts*
      Tushar Jois, Gabrielle Beck, Sofia Belikovetsky, Joseph Carrigan, Alishah Chator, Logan Kostick, Maximilian Zinkus, Gabriel Kaptchuk, Avi Rubin. [PDF]
      PoPETS 2024
  • Scalable Multiparty Garbling
      Gabrielle Beck, Aarushi Goel, Aditya Hegde, Abhishek Jain, Zhengzhong Jin, and Gabriel Kaptchuk. [eprint PDF]
      ACM CCS 2023
  • What Are the Chances? Explaining the Epsilon Parameter in Differential Privacy*
      Priyanka Nanayakkara, Mary Anne Smart, Rachel Cummings, Gabriel Kaptchuk, and Elissa M. Redmiles. [arXiv] [Conference PDF]
      USENIX Security 2023
  • Speed-Stacking: Fast Sublinear Zero-Knowledge Proofs for Disjunctions
      Aarushi Goel, Mathias Hall-Andersen, Gabriel Kaptchuk, and Nicholas Spooner. [eprint PDF] [Conference Talk]
      EUROCRYPT 2023
  • Efficient Proofs of Software Exploitability for Real-world Processors
      Matthew Green, Mathias Hall-Andersen, Eric Hennenfent, Gabriel Kaptchuk, Benjamin Perez, and Gijs Van Laer. [eprint PDF] [Conference PDF] [Code] [Conference Talk]
      PoPETS 2023
  • Stacking Sigmas: A Framework to Compose Σ-Protocols for Disjunctions.
      Aarushi Goel, Matthew Green, Mathias Hall-Andersen, and Gabriel Kaptchuk. [eprint PDF] [Code] [Conference Talk]
      EUROCRYPT 2022
  • Efficient Set Membership using MPC-in-the-Head.
      Aarushi Goel, Matthew Green, Mathias Hall-Andersen, and Gabriel Kaptchuk. [eprint PDF] [Code] [Conference PDF] [Conference Talk]
      PoPETS 2022
  • How good is good enough for COVID19 apps? The influence of benefits, accuracy, and privacy on willingness to adopt.*
      Gabriel Kaptchuk, Daniel G. Goldstein, Eszter Hargittai, Jake Hofman, and Elissa M. Redmiles. [Journal Version] [arXiv]
      ACM Digital Threats: Research and Practice Special Issue on COVID-19
  • Fluid MPC: Secure Multiparty Computation with Dynamic Participants.
      Arka Rai Choudhuri, Aarushi Goel, Matthew Green, Abhishek Jain, and Gabriel Kaptchuk. [eprint PDF] [Conference Talk]
      CRYPTO 2021
  • Meteor: Cryptographically Secure Steganography for Realistic Distributions.*
     Gabriel Kaptchuk, Tushar Jois, Matthew Green, and Aviel D. Rubin. [PDF] [eprint PDF] [Website & Demo with Code] [Conference Talk]
      ACM CCS 2021
  • "I need a better description": An Investigation Into User Expectations For Differential Privacy (Best Paper Runner-up)
     Rachel Cummings, Gabriel Kaptchuk, and Elissa Redmiles. [PDF] [arXiv] [TPDP Poster] [Conference Talk]
      ACM CCS 2021
  • Abuse Resistant Law Enforcement Access Systems
     Matthew Green, Gabriel Kaptchuk, and Gijs Van Laer. [eprint PDF] [Conference Talk]
      EUROCRYPT 2021
  • Order-C Secure Multiparty Computation for Highly Repetitive Circuits
     Gabrielle Beck, Aarushi Goel, Abhishek Jain, and Gabriel Kaptchuk. EUROCRYPT 2021 [eprint PDF] [Conference Talk]
      EUROCRYPT 2021
  • Improving Signal's Sealed Sender.*
     Ian Martiny, Gabriel Kaptchuk, Adam Aviv, Daniel Roche, and Eric Wustrow. [PDF] [Code] [Conference Talk]
      NDSS 2021
  • Giving State to the Stateless: Augmenting Trustworthy Computation with Ledgers.*
     Gabriel Kaptchuk, Ian Miers, Matthew Green. [eprint PDF][Conference PDF][Code] [Conference Talk]
      NDSS 2019
  • Fairness in an Unfair World: Fair Multiparty Computation from Public Bulletin Boards.
      Arka Rai Choudhuri, Matthew Green, Abhishek Jain, Gabriel Kaptchuk, Ian Miers. [eprint PDF] [Conference PDF] [Conference Talk]
      ACM CCS 2017
  • Outsourcing Medical Dataset Analysis: A Possible Solution.*
      Gabriel Kaptchuk, Matthew Green, Aviel D. Rubin. Financial Cryptography Conference 2017. [PDF]
      Financial Crypto 2017
  • Dancing on the Lip of the Volcano: Chosen Ciphertext Attacks on Apple iMessage.
      Christina Garman, Matthew Green, Gabriel Kaptchuk, Ian Miers, Michael Rushanan. [PDF] [Conference Talk]
      USENIX Security 2016
  • A Practical Implementation of a Multi-Device Split Application for Protecting Online Poker.
      Gabriel Kaptchuk, Aviel D. Rubin. [PDF]
      Annual Security Conference 2016

Publicly Recorded Talks

  • The Good, The Bad, and The Ugly: Lessons from an MPC for Social Good Deployment (RWC 2024) [Video] [PDF Slides]
  • Efficient Proofs of Software Exploitability for Real-world Processors (PETs 23) [Video] [PPTX Slides]
  • What Are the Consequences of Backdoors for Online Privacy? A Panel Discussion Hosted by Center for Data Innovation. [Video]
  • Future of Computer Research 2022: Early Career Researchers Roundtable [Video]
  • Efficient Set Membership using MPC-in-the-Head. (PETs 22) [Video] [PDF Slides]
  • Commit Acts of Steganography—Before it's too late. (RWC 2022) [Video] [PDF Slides]
  • Weaving Social Accountability Into Cryptographic Protocols (Charles River Area Crypto Day 2022) [PPTX Slides]
  • Meteor: Cryptographically Secure Steganography for Realistic Distributions. (ACM CCS 2021) [Video] [PDF Slides]
  • "I need a better description": An Investigation Into User Expectations For Differential Privacy. (ACM CCS 2021) [Video] [PDF Slides]
  • Abuse Resistant Law Enforcement Access Systems. (EUROCRYPT 2021) [Video] [PDF Slides]
  • Order-C Secure Multiparty Computation for Highly Restitive Circuits. (EUROCRYPT 2021) [Video] [PDF Slides]
  • Giving State to the Stateless: Augmenting Trustworthy Computation with Ledgers (NDSS 2019) [Video] [PDF Slides]
  • The Hill We Must Die On: Cryptographers and Congress (RWC 2019) [Video] [PDF Slides]
  • Presentation for Fairness in an Unfair World (CCS 2017) [Video] [PPTX Slides]

Press / Blogs