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Alex Davidson is an Assistant Professor in the Computer Science department of Universidade de Lisboa, and an affiliated member of LASIGE. His research is conducted in the fields of cryptography, privacy, and usable security mechanisms, particularly based in the Internet setting. He was awarded his PhD in 2018 by Royal Holloway, University of London, UK, for his thesis "Computing Functions Securely: Theory, Implementation, and Practice", and a Bachelors of Science with Honours in Mathematics (awarded First Class Honours) from the University of Warwick. His main research interests are in constructing and implementing novel cryptographic functionalities and protocols. Until recently, he was an Assitant Professor at NOVA FCT. He has published articles across a variety of top-tier academic conferences in cryptography and security. Previously, since being awarded his PhD, he has worked as a Cryptography Researcher in Technology companies such as Cloudflare (2018-2020), and Brave Software (2021-2022). He also worked as a post-doctoral researcher on the ERC-funded Fake News and Real People (FARE) project led by Joana G. Sá. Other activities and awards: Alex has also been involved as an author of numerous standardisation efforts within the Internet Engineering Task Force, and is a listed author of RFC 9497 (https://datatracker.ietf.org/doc/rfc9497/), RFC 9576 (https://datatracker.ietf.org/doc/rfc9576/), and RFC 9578 (https://datatracker.ietf.org/doc/rfc9578/). His research has resulted in receiving three distinguished paper awards (NDSS 2025, ACM CCS 2022, PETS 2018), and one Top Reviewer award (ACM CCS 2024) for services to peer reviewing. He has served as a program committee member for numerous top tier conferences, including ACM CCS, IACR Eurocrypt, IEEE Euro S&P and PoPETS. Funded projects: In 2024, he was PI for the project "CertiCoLab: Collaborative Laboratory for Investigating Certifiable Computation" funded by EEA Grants (16367,10€, Grace code: PT-BI095) in collaboration with Simula UiB, Norway. Since February 2026, he is PI of the FCT project "CODEFHE: Fully-Homomorphic Encryption from Post-Quantum Code-Based Assumptions", funded as part of the CMU Portugal Exploratory Research Projects Program (total funding: 67256€). He has also participated as a team member in the FCT project 2024.07643.IACDC. Research Topics: Cryptography; Privacy Enhancing Technologies; Usable Security Mechanisms. Google Scholar: https://scholar.google.co.uk/citations?user=HKAfgQUAAAAJ Selected Publications (2020-2025): 1. Pool: A Practical OT-based OPRF from Learning with Rounding. Authors: Alex Davidson, Amit Deo, and Louis Tremblay Thibault. Proceedings of the 2025 ACM SIGSAC Conference on Computer and Communications Security. CCS 2025. URL: https://eprint.iacr.org/2025/1816 2. [Distinguished Paper Award] DiStefano: Decentralized Infrastructure for Sharing Trusted Encrypted Facts and Nothing More. Authors: Sofía Celi, Alex Davidson, Hamed Haddadi, Gonçalo Pestana, and Joe Rowell. Proceedings of the 2025 Network and Distributed System Security (NDSS) Symposium. 2025. URL: https://eprint.iacr.org/2023/1063. 3. Call Me By My Name: Simple, Practical Private Information Retrieval for Keyword Queries. Authors: Sofía Celi, Alex Davidson. Proceedings of the 2025 ACM SIGSAC Conference on Computer and Communications Security. 2025. URL: https://eprint.iacr.org/2024/092.pdf 4. Crypto Dark Matter on the Torus: Oblivious PRFs from shallow PRFs and FHE. Authors: Martin R. Albrecht, Alex Davidson, Amit Deo, Daniel Gardham. IACR Eurocrypt 2024, Zurich, 2024. URL: https://eprint.iacr.org/2023/232. 5. [Distinguished Paper Award] STAR: Secret Sharing for Private Threshold Aggregation Reporting. Authors: Alex Davidson, Peter Snyder, E. B. Quirk, Joseph Genereux, Benjamin Livshits, Hamed Haddadi. Proceedings of the 2022 ACM SIGSAC Conference on Computer and Communications Security. CCS 2022.. URL: https://dl.acm.org/doi/10.1145/3548606.3560631.
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Identification

Personal identification

Full name
Alexander Andrew Davidson

Citation names

  • Davidson, Alexander
  • Davidson, Alex

Author identifiers

Ciência ID
981A-2C57-2815
ORCID iD
0000-0001-9157-3821
Google Scholar ID
HKAfgQUAAAAJ

Email addresses

  • a.davidson@fct.unl.pt (Professional)
  • aadavidson@fc.ul.pt (Professional)

Telephones

Mobile phone
  • 963452432 (Personal)

Knowledge fields

  • Exact Sciences - Computer and Information Sciences

Languages

Language Speaking Reading Writing Listening Peer-review
English (Mother tongue)
Portuguese Upper intermediate (B2) Upper intermediate (B2) Upper intermediate (B2) Upper intermediate (B2)
Education
Degree Classification
2014/09/20 - 2019/07/01
Concluded
 Information Security (Doctor of Philosophy)
Royal Holloway University of London, United Kingdom
"Computing Functions Securely: Theory, Implementation and Cryptanalysis (Supervisor: Carlos Cid)" (THESIS/DISSERTATION)
 Approved
2010/10/01 - 2013/07/03
Concluded
 BSC Hons Mathematics (Bachelor)
University of Warwick, United Kingdom
 First Class Honours
Affiliation

Science

Category
Host institution		 Employer
2024/12/30 - Current Researcher (Research) LASIGE Laboratório de Sistemas Informáticos de Grande Escala, Portugal
2023/02/01 - 2024/12/30 Researcher (Research) Universidade Nova de Lisboa Laboratório para a Ciência da Computação e Informática, Portugal
Universidade Nova de Lisboa Laboratório para a Ciência da Computação e Informática, Portugal
2020/11/15 - 2021/05/28 Postdoc (Research) Laboratório de Instrumentação e Física Experimental de Partículas, Portugal
Laboratório de Instrumentação e Física Experimental de Partículas, Portugal
2018/02/01 - 2018/05/05 Visiting Researcher (Research) NTT Advanced Technology Kabushiki Kaisha Musashino Center Building, Japan

Teaching in Higher Education

Category
Host institution		 Employer
2024/12/30 - Current Assistant Professor (University Teacher) Universidade de Lisboa Faculdade de Ciências, Portugal
2023/02/01 - 2024/12/30 Assistant Professor (University Teacher) Universidade NOVA de Lisboa Faculdade de Ciências e Tecnologia, Portugal
Universidade Nova de Lisboa Departamento de Informática, Portugal

Others

Category
Host institution		 Employer
2021/05/31 - 2022/11/24 Cryptography Researcher Brave Software, United States
2018/10/15 - 2020/09/30 Cryptography Engineer Cloudflare, Portugal
2017/07/01 - 2017/10/01 Cryptography Engineer Internship Cloudflare, Portugal
2016/06/15 - 2016/09/30 Cryptography Engineer Internship Cloudflare, Portugal
Projects

Grant

Designation Funders
2020/11/15 - 2021/05/31 FARE: FAKE NEWS AND REAL PEOPLE: USING BIG DATA TO UNDERSTAND HUMAN BEHAVIOUR
853566
Post-doc
Laboratório de Instrumentação e Física Experimental de Partículas, Portugal
 European Research Council
Concluded
2014/09/20 - 2019/07/03 Centre for Doctoral Training in Cyber Security at Royal Holloway
EP/K035584/1
PhD Student Fellow
Royal Holloway University of London, United Kingdom
 Engineering and Physical Sciences Research Council
Concluded

Contract

Designation Funders
2025/10/01 - 2026/09/30 Fully-Homomorphic Encryption from Post-Quantum Code-Based Assumptions
2024.12595.CMU
10.54499/2024.12595.CMU
Partner Lead
Instituto de Telecomunicações Lisboa, Portugal

FCiênciasID Associação para a Investigação e Desenvolvimento de Ciências, Portugal
 Fundação para a Ciência e a Tecnologia
Ongoing
2025/03/01 - 2026/01/31 ParSec: Astrnomically Improving Parliamentary Cybersecurity through Collective Authorization
2024.07643.IACDC
10.54499/2024.07643.IACDC
Researcher
Universidade Nova de Lisboa Associação para a Inovação e Desenvolvimento da FCT, Portugal
 Fundação para a Ciência e a Tecnologia
Ongoing
2024/01/01 - 2024/12/31 CertiCoLab: Collaborative Laboratory for Investigating Certifiable Computation
PT-BI095
Principal investigator
Universidade NOVA de Lisboa Faculdade de Ciências e Tecnologia, Portugal
 EEA Grants
Ongoing
2020/01/01 - 2024/12/31 NOVA Laboratory for Computer Science and Informatics
UIDB/04516/2020
10.54499/UIDB/04516/2020
Universidade Nova de Lisboa Laboratório para a Ciência da Computação e Informática, Portugal

Universidade Nova de Lisboa, Portugal

Universidade de Évora, Portugal

Universidade Nova de Lisboa Associação para a Inovação e Desenvolvimento da FCT, Portugal
 Fundação para a Ciência e a Tecnologia
Concluded
Outputs

Publications

Conference paper
  1. Davidson, Alex; Virdia, Fernando; Luiza Soezima. "Practical Semi-Open Chat Groups for Secure Messaging Applications". Paper presented in Privacy Enhancing Technologies Symposium (PoPETS) 2026, Calgary, 2026.
    Accepted
  2. Davidson, Alex; Carlos Cid; Atharva Phanse. Corresponding author: Atharva Phanse. "Practice-Oriented Instances of Deterministic LPN". Paper presented in Applied Cryptography and Network Security (ACNS), New York City, 2026.
    Accepted
  3. Davidson, Alex; Haddadi, Hamed; Maheri, Mohammad; Sunil Cotterill. "ZK-APEX: Zero-Knowledge Approximate Personalized Unlearning with Executable Proofs". Paper presented in Annual Conference on Machine Learning and Systems (MLSys), Bellevue, 2026.
    Accepted
  4. Davidson, Alex; Deo, Amit; Tremblay Thibault, Louis. "Pool: A Practical OT-based OPRF from Learning with Rounding". Paper presented in ACM Conference on Computer and Communications Security (CCS) 2025, Taipei, 2025.
    Published • 10.1145/3719027.3765054
  5. Maheri, Mohammad M; Haddadi, Hamed; Davidson, Alex. "TeleSparse: Practical Privacy-Preserving Verification of Deep Neural Networks". Paper presented in Privacy Enhancing Technologies Symposium (PoPETS) 2024, Washington DC, 2025.
    Published • 10.56553/popets-2025-0161
  6. Sofía Celi; Davidson, Alex; Haddadi, Hamed; Gonçalo Pestana; Joe Rowell. "DiStefano: Decentralized Infrastructure for Sharing Trusted Encrypted Facts and Nothing More". Paper presented in Network and Distributed System Security Symposium (NDSS) 2025, San Diego, 2025.
  7. Sofía Celi; Alex Davidson. "Call Me By My Name: Simple, Practical Private Information Retrieval for Keyword Queries". Paper presented in ACM CCS 2024, 2024.
    Accepted
  8. Vilalonga, Afonso; Gallagher, Kevin; Davidson, Alex; Domingos, Henrique. Corresponding author: Vilalonga, Afonso. "Comunicação: Algoritmos de Resposta Aleatória como Mecanismo para a Desvinculação entre o Tráfego de Entrada e de Saída em Sistemas de Anonimato Baseados em Circuitos". Paper presented in 15º Simpósio Nacional de Informática, Lisboa, 2024.
    Published
  9. Albrecht, Martin R.; Davidson, Alex; Deo, Amit; Daniel Gardham. "Crypto Dark Matter on the Torus: Oblivious PRFs from shallow PRFs and FHE". Paper presented in IACR Eurocrypt 2024, Zurich, 2024.
    Accepted
  10. Davidson, Alex; Gonçalo Pestana; Sofía Celi. Corresponding author: Davidson, Alex. "FrodoPIR: Simple, Scalable, Single-Server Private Information Retrieval". Paper presented in Proceedings on Privacy Enhancing Technologies (PoPETs) 2023, Lausanne, 2023.
    Published
  11. Davidson, A.; Frei, M.; Gartner, M.; Haddadi, H.; Perrig, A.; Nieto, J. Subirà; Winter, P.; Wirz, F.. "Tango or square dance?: how tightly should we integrate network functionality in browsers?". Paper presented in HotNets 2022: Twenty-First ACM Workshop on Hot Topics in Networks, 2022.
    Published • 10.1145/3563766.3564111
  12. Davidson, Alex; Snyder, Peter; Quirk, E. B.; Genereux, Joseph; Livshits, Benjamin; Haddadi, Hamed. "STAR: Secret Sharing for Private Threshold Aggregation Reporting". Paper presented in Proceedings of the 2022 ACM SIGSAC Conference on Computer and Communications Security, Los Angeles, 2022.
    Published • 10.1145/3548606.3560631
  13. Tara Whalen; Thibault Meunier; Mrudula Kodali; Alex Davidson; Marwan Fayed; Armando Faz-Hernández; Watson Ladd; et al. "Let The Right One In: Attestation as a Usable CAPTCHA Alternative". Paper presented in Eighteenth Symposium on Usable Privacy and Security 2022, Boston, MA, 2022.
    Published
  14. Albrecht, Martin R.; Davidson, Alex; Deo, Amit; Smart, Nigel. "Round-optimal Verifiable Oblivious Pseudorandom Functions from Ideal Lattices". Paper presented in 24th IACR International Conference on Practice and Theory of Public Key Cryptography, 2021.
    Published
  15. Davidson, Alex; Katsumata, Shuichi; Nishimaki, Ryo; Yamada, Shota; Yamakawa, Takashi. "Adaptively Secure Constrained Pseudorandom Functions in the Standard Model". Paper presented in 40th Annual International Cryptology Conference, CRYPTO 2020, Santa Barbara, 2020.
    Published • 10.1007/978-3-030-56784-2_19
  16. Davidson, Alex; Deo, Amit; Lee, Ela; Martin, Keith. "Strong Post-Compromise Secure Proxy Re-Encryption". Paper presented in Australasian Conference on Information Security and Privacy, Christchurch, 2019.
    Published • 10.1007/978-3-030-21548-4_4
  17. Albrecht, Martin R.; Curtis, Benjamin R.; Deo, Amit; Davidson, Alex; Player, Rachel; Postlethwaite, Eamonn W.; Virdia, Fernando; Wunderer, Thomas. "Estimate All the {LWE, NTRU} Schemes!". Paper presented in Security and Cryptography for Networks 2018, Amalfi, 2018.
    Published • 10.1007/978-3-319-98113-0_19
  18. Davidson, Alex; Goldberg, Ian; Sullivan, Nick; Tankersley, George; Valsorda, Filippo. "Privacy Pass: Bypassing Internet Challenges Anonymously". Paper presented in Proceedings on Privacy Enhancing Technologies (PoPETs) 2018, Barcelona, 2018.
    Published • 10.1515/popets-2018-0026
  19. Albrecht, Martin R.; Davidson, Alex; Larraia, Enrique. "Notes on GGH13 Without the Presence of Ideals". Paper presented in 17th IMA International Conference on Cryptography and Coding 2017, Oxford, 2017.
    Published • 10.1007/978-3-319-71045-7_8
  20. Davidson, Alex; Cid, Carlos. "An Efficient Toolkit for Computing Private Set Operations". Paper presented in Australasian Conference on Information Security and Privacy 2017, Auckland, 2017.
    Published • 10.1007/978-3-319-59870-3_15
  21. Davidson, Alex; Fenn, Gregory; Cid, Carlos. "A Model for Secure and Mutually Beneficial Software Vulnerability Sharing". Paper presented in Proceedings of the 2016 ACM on Workshop on Information Sharing and Collaborative Security, Vienna, 2016.
    Published • 10.1145/2994539.2994547
Preprint
  1. Davidson, Alex; Nishimaki, Ryo. "A Bit-fixing PRF with O (1) Collusion-Resistance from LWE". 2018. https://eprint.iacr.org/2018/890.
Thesis / Dissertation
  1. Alex Davidson. "Computing Functions Securely: Theory, Implementation and Cryptanalysis". PhD, Royal Holloway University of London, 2019. https://pure.royalholloway.ac.uk/portal/en/publications/computing-functions-securely-theory-implementation-and-cryptanalysis(a89cdc2e-e6bd-4a3e-80dc-548d1f39e8c9).html.

Other

Technical standard
  1. RFC 9576 Privacy Pass Architectural Framework. This Internet standard specifies the architectural framework for establishing anonymity-preserving instantiations of the Privacy Pass protocol. Document originated from a prior lead-author publication (DOI: 0.1515/popets-2018-0026). 2024. Davidson, Alex. https://datatracker.ietf.org/doc/rfc9576/.
  2. RFC 9578 Privacy Pass Issuance Protocols. This Internet standard specifies the Privacy Pass protocol. This protocol provides anonymity-preserving authorization of clients to servers. Document originated from a prior lead-author publication (DOI: 0.1515/popets-2018-0026). 2024. Davidson, Alex. https://datatracker.ietf.org/doc/rfc9578/.
  3. RFC 9497 Oblivious Pseudorandom Functions (OPRFs) Using Prime-Order Groups. Internet standard describing implementation framework for oblivious pseudorandom function protocols. Such protocols are commonly used in preserving the privacy of Internet users during authorisation procedures on the Internet. Document originated from a prior lead-author publication (DOI: 0.1515/popets-2018-0026). 2023. Davidson, Alex. https://datatracker.ietf.org/doc/draft-irtf-cfrg-voprf/.
Activities

Oral presentation

Presentation title Event name
Host (Event location)
2024/06/19 Challenges and Future Innovations in Privacy-Preserving Data Analysis C-Days Cibersegurança
Centro Nacional de Cibersegurança Portugal (Coimbra, Portugal)
2023/10/03 Invited Talk: "Private Information Retrieval" ASCrypto (Affiliated with Latincrypt 2023)
(Quito, Ecuador)
2023/07 Paper presentation: FrodoPIR: Simple, Scalable Private Information Retrieval Privacy Enhancing Technologies Symposium (PoPETs) 2023
EPFL, University of Lausanne (Lausanne, Switzerland)
2022/11/28 Invited Talk: "STAR: Low-Cost Private Analytics for Everyone" London-ish Crypto Day
Google (London, United Kingdom)
2021/05 Paper presentation: Round-Optimal Verifiable Oblivious Pseudorandom Functions From Ideal Lattices International Conference on Practice and Theory of Public-Key Cryptography (PKC)
Remote (Remote)
2020/08/15 Invited Talk: "Privacy Pass: Standardizing Anonymous Authorization for the Internet" 2nd Workshop on Advanced Cryptography Applications and Standards
IACR Crypto 2020 (United States)
2020/07/31 Invited Talk: "Privacy Pass: Architectural Framework" Privacy Pass Working Group meeting
IETF 108
2018/07 Paper presentation: Privacy Pass: Bypassing Internet Challenges Anonymously Privacy Enhancing Technologies Symposium (PoPETs) 2018
University of Barcelona (Barcelona, Spain)
2017/07 Paper presentation: An Efficient Toolkit for Computing Private Set Operations Australasian Conference on Information Security and Privacy (ACISP) 2017
Massey University (Auckland, New Zealand)

Supervision

Thesis Title
Role		 Degree Subject (Type)
Institution / Organization
2023/09/01 - Current Usability study of the Signal Secure Messaging protocol
Co-supervisor of Romão Costa
 Engenharia Informática (Master)
Universidade NOVA de Lisboa Faculdade de Ciências e Tecnologia, Portugal
2023/09/01 - Current Improving the strength of the Tor Anonymity Network using Differential Privacy
Co-supervisor of Rui Genovevo
 Engenharia Informática (Master)
Universidade NOVA de Lisboa Faculdade de Ciências e Tecnologia, Portugal
2023/02/01 - Current Constructing Trusted Inputs For Secure Multi-Party Computation Protocols
Supervisor of Tiago Morais
 Engenharia Informática (Master)
Universidade NOVA de Lisboa Faculdade de Ciências e Tecnologia, Portugal
2023/02/01 - Current Usage Of Private Information Retrieval Protocols In Audio Streaming
Supervisor of Rafael Costa
 Engenharia Informática (Master)
Universidade NOVA de Lisboa Faculdade de Ciências e Tecnologia, Portugal
2023/02/01 - Current Investigating Key Rotation Security in Oblivious Pseudorandom Function Protocols
Co-supervisor of Diogo Ramos
 Engenharia Informática (Master)
Universidade NOVA de Lisboa Faculdade de Ciências e Tecnologia, Portugal

Event organisation

Event name
Type of event (Role)		 Institution / Organization
2020/03/26 - 2020/03/26 Organisation of Internet Engineering Task Force (IETF) meeting to gauge interest in standardisation of Privacy Pass protocol (https://datatracker.ietf.org/doc/agenda-107-privacypass/). (2020/03/26 - 2020/03/26)
Meeting (Co-organisor)
 Internet Society, United States

Conference scientific committee

Conference name Conference host
2026/01/01 - Current ACM Computer and Communications Security (CCS) 2026
2025/10/01 - Current IEEE European Security and Privacy 2026
2025/07/01 - Current ACM Asia Computer and Communications Security (AsiaCCS) 2026
2025/07/01 - Current Privacy Enhancing Technologies Symposium (PoPETS) 2026
2025/01/01 - Current ACM Conference on Computer and Communications Security (CCS) 2025
2024/07/01 - Current Privacy Enhancing Technologies Symposium (PoPETS) 2025
2024/10/01 - 2025/05 IACR Eurocrypt 2025
2024 - 2024 ACM Conference on Computer and Communications Security (CCS) 2024 Salt Lake City, USA
2023 - 2024 Privacy Enhancing Technologies Symposium (PoPETS) 2024 Zurich, Switzerland
2023 - 2023 19th IMA International Conference on Cryptography and Coding (IMACC) Royal Holloway, University of London
2019 - 2019 17th IMA International Conference on Cryptography and Coding (IMACC) Institute of Mathematics, University of Oxford, UK
Distinctions

Award

2025 Distinguished Paper Award: "DiStefano: Decentralized Infrastructure for Sharing Trusted Encrypted Facts and Nothing More"
Network and Distributed System Security (NDSS) Symposium 2025, United States
2024 Top Reviewer
ACM Computer and Communications Security Conference (ACM CCS) 2024, United States
2022 Distinguished Paper Award (Paper title: "STAR: Secret Sharing for Private Threshold Aggregation Reporting", Authors: Alex Davidson, Peter Snyder, E. B. Quirk, Joseph Genereux, Benjamin Livshits, Hamed Haddadi)
ACM CCS 2022, United States
2018 The Andreas Pfitzmann Best Student Paper Award (Paper title: "Privacy Pass: Bypassing Internet Challenges Anonymously", Authors: A Davidson, I Goldberg, N Sullivan, G Tankersley, F Valsorda)
Privacy Enhancing Technologies Symposium 2018, Spain