You can also find an up-to-date list of my publications at my DBLP or Google Scholar Profile.

Conference Papers

James Hsin-yu Chiang, Bernardo David, Ittay Eyal, Tiantian Gong. FairPoS: Input Fairness in Proof-of-Stake with Adaptive Security. AFT 2023.

James Hsin-yu Chiang, Bernardo David, Mariana Gama, Christian Janos Lebeda. Correlated-Output-Differential-Privacy and Applications to Dark Pools. AFT 2023.

Carsten Baum, James Hsin-yu Chiang, Bernardo David, Tore Kasper Frederiksen. SoK: Privacy-Enhancing Technologies in Finance. AFT 2023.

Bernardo David, Yuval Ishai, Anders Konring, Eyal Kushilevitz, Varun Narayanan: Perfect MPC over Layered Graphs. CRYPTO 2023.

Joakim Brorsson, Bernardo David, Lorenzo Gentile, Elena Pagnin, Paul Stankovski Wagner. PAPR: Publicly Auditable Privacy Revocation for Anonymous Credentials. CT-RSA 2023.

Ignacio Cascudo, Bernardo David, Omer Shlomovits, Denis Varlakov. Mt. Random: Multi-tiered Randomness Beacons. ACNS 2023.

Carsten Baum, Bernardo David, Rafael Dowsley, Ravi Kishore, Jesper Buus Nielsen, Sabine Oechsner. CRAFT: Composable Randomness Beacons and Output-Independent Abort MPC From Time. PKC 2023.

Carsten Baum, James Hsin-yu Chiang, Bernardo David, Tore Kasper Frederiksen: Eagle: Efficient Privacy Preserving Smart Contracts. Financial Cryptography 2023.

Steven Golob, Sikha Pentyala, Rafael Dowsley, Bernardo David, Mario Larangeira, Martine De Cock, Anderson Nascimento. A Decentralized Information Marketplace Preserving Input and Output Privacy. ACM 2nd Data Economy Workshop Co-Located with ACM SIGMOD 2023.

Ignacio Cascudo, Bernardo David, Lydia Garms, Anders Konring. YOLO YOSO: Fast and Simple Encryption and Secret Sharing in the YOSO Model. ASIACRYPT 2022.

Matteo Campanelli, Bernardo David, Hamidreza Khoshakhlagh, Anders Konring, Jesper Buus Nielsen. Encryption to the Future: A Paradigm for Sending Secret Messages to Future (Anonymous) Committees. ASIACRYPT 2022.

Carsten Baum, Bernardo David, Rafael Dowsley. A Framework for Universally Composable Publicly Verifiable Cryptographic Protocols. ProvSec 2022.

Bernardo David, Bernardo Magri, Christian Matt, Jesper Buus Nielsen, Daniel Tschudi. GearBox. An Efficient UC Sharded Ledger Leveraging the Safety-Liveness Dichotomy. CCS 2022.

Carsten Baum, James Hsin-yu Chiang, Bernardo David, Tore Kasper Frederiksen, Lorenzo Gentile. SoK: Mitigation of Front-running in Decentralized Finance. 2nd Workshop on Decentralized Finance, Financial Cryptography 2022.

Bernardo David, Lorenzo Gentile, Mohsen Pourpouneh. FAST: Fair Auctions via Secret Transactions. ACNS 2022.

Carsten Baum, Bernardo David, Tore Frederiksen. P2DEX: Privacy-Preserving Decentralized Cryptocurrency Exchange. ACNS 2021.

Carsten Baum, Bernardo David, Rafael Dowsley, Jesper Buus Nielsen, Sabine Oechsner. TARDIS: A Foundation of Time-Lock Puzzles in UC. EUROCRYPT 2021

Ignacio Cascudo, Bernardo David. ALBATROSS: Publicly AttestabLe BATched Randomness Based On Secret Sharing. ASIACRYPT 2020

Bernardo David, Rafael Dowsley. Efficient Composable Oblivious Transfer from CDH in the Global Random Oracle Model. In: CANS 2020

Carsten Baum, Bernardo David, Rafael Dowsley. Insured MPC: Efficient Secure Multiparty Computation with Punishable Abort. In: Financial Cryptography 2020

Ignacio Cascudo, Ivan Damgård, Bernardo David, Nico Döttling, Rafael Dowsley, Irene Giacomelli. Efficient UC Commitment Extension with Homomorphism for Free (and Applications) In: Asiacrypt 2019.

Bernardo David, Rafael Dowsley, Mario Larangeira: ROYALE: A Framework for Universally Composable Card Games with Financial Rewards and Penalties Enforcement. In: Financial Cryptography 2019

Bernardo David, Rafael Dowsley, Mario Larangeira: 21 - Bringing Down the Complexity: Fast Composable Protocols for Card Games Without Secret State. ACISP 2018

Bernardo David, Rafael Dowsley, Mario Larangeira: MARS: Monetized Ad-hoc Routing System (A Position Paper). In: CRYBLOCK@MobiSys 2018

Bernardo David, Peter Gazi, Aggelos Kiayias, Alexander Russel: Ouroboros Praos: An adaptively-secure, semi-synchronous proof-of-stake protocol. In: Eurocrypt 2018

Bernardo David, Rafael Dowsley, Mario Larangeira: Kaleidoscope: An Efficient Poker Protocol with Payment Distribution and Penalty Enforcement. In: Financial Cryptography 2018

Aggelos Kiayias, Alexander Russel, Bernardo David, Roman Oliynykov: Ouroboros: A Provably Secure Proof-of-Stake Blockchain Protocol. In: Crypto 2017

Ignacio Cascudo, Bernardo David: SCRAPE: Scalable Randomness Attested by Public Entities. In: ACNS 2017.

Ignacio Cascudo, Ivan Damgård, Bernardo David, Nico Döttling, Jesper Buus Nielsen: Rate-1, Linear Time and Additively Homomorphic UC Commitments. In: Crypto 2016.

Bernardo David, Rafael Dowsley, Raj Katti, and Anderson C. A. Nascimento: Efficient Unconditionally Secure Comparison and Privacy Preserving Machine Learning Classification Protocols. In: Provsec 2015.

Bernardo David, Ryo Nishimaki, Samuel Ranellucci, Alain Tapp: Generalizing Efficient Multiparty Computation. In: ICITS 2015.

Ignacio Cascudo, Ivan Damgård, Bernardo David, Irene Giacomelli, Jesper Buus Nielsen, Roberto Trifiletti: Additively Homomorphic UC commitments with Optimal Amortized Overhead. In: PKC 2015.

Ivan Damgård, Bernardo David, Irene Giacomelli, Jesper Buus Nielsen: Compact VSS and Efficient Homomorphic UC Commitments. In: Asiacrypt 2014.

Bernardo David, Rafael Dowsley, Anderson C. A. Nascimento: Universally Composable Oblivious Transfer based on a variant of LPN. In: CANS 2014.

Masayuki Abe, Bernardo David, Markulf Kohlweiss, Ryo Nishimaki, Miyako Ohkubo: Tagged One-Time Signatures: Tight Security and Optimal Tag Size. In: PKC 2013.

Masayuki Abe; Melissa Chase; Bernardo David; Markulf Kohlweiss; Miyako Okhubo; Ryo Nishimaki. Constant-Size Structure Preserving Signatures: Generic Constructions and Simple Assumptions. In: Asiacrypt 2012.

Adriana Pinto; Bernardo David; Anderson C. A. Nascimento; Jeroen Van de Graaf. Universally Composable Committed Oblivious Transfer with a Trusted Initializer. In: SBSEG 2012. (Best Paper Award)

Bernardo David ; Anderson C. A. Nascimento; Joern Mueller-Quade. Universally Composable Oblivious Transfer From Lossy Encryption And The McEliece Assumptions. IN: ICITS 2012.

Bernardo David ; Anderson C. A. Nascimento . Efficient fully simulatable oblivious transfer from the McEliece assumptions. In: IEEE Information Theory Workshop (ITW), 2011.

QUELHO, R. T. M. ; Bernardo David ; Alves, V. M. . Universally Composable Private Proximity Testing. In: Provsec 2011.

Bernardo David ; QUELHO, R. T. M. ; Anderson C. A. Nascimento . Obtaining Efficient Fully Simulatable Oblivious Transfer from General Assumptions. In: SBSEG 2011.

Journal Papers

Masayuki Abe, Melissa Chase, Bernardo David, Markulf Kohlweiss, Ryo Nishimaki, Miyako Ohkubo. Constant-Size Structure-Preserving Signatures: Generic Constructions and Simple Assumptions. In: Journal of Cryptology (2015).

Bernardo David, Rafael Dowsley, Jeroen van de Graaf, Davidson Marques, Anderson C. A. Nascimento, Adriana C. B. Pinto. Unconditionally Secure, Universally Composable Privacy Preserving Linear Algebra. In: IEEE Transactions on Information Forensics and Security (2015).

Bernardo David; Anderson C. A. Nascimento. Fully Simulatable Oblivious Transfer Based on The McEliece Assumptions. In: IEICE Transactions 95-A(11): 2059-2066 (2012)

Network Security

Bernardo David ; Anderson C. A. Nascimento ; QUELHO, R. T. M. ; Rafael Timoteo de Sousa Junior . A framework for secure single sign-on. In: Workshop de Gestao de Identidades Digitais, SBSEG 2012.

Bernardo David; da Costa, J. P. C. L. ; Amaral, D. ; Rafael Timoteo de Sousa Junior ; FREITAS, E. P. ; SERRANO, A. M. R. . Improved Blind Automatic Malicious Activity Detection in Honeypot Data. In: ICoFCS 2012. (Best Paper Award)

Holtz, M. D. ; Bernardo David ; Sousa Jr., R. T. . An architecture for distributed Network Intrusion Detection based on the Map-Reduce Framework. In: IWT 2011.

Bernardo David ; da Costa, J. P. C. L. ; Anderson C. A. Nascimento ; Holtz, M. D. ; Amaral, D. ; Sousa Jr., R. T. . Blind Automatic Malicious Activity Detection in Honeypot Data. In: ICoFCS 2011.

Bernardo David ; Sousa Jr., R. T. . A Bayesian Trust Model for the MAC Layer in IEEE 802.15.4 Networks. In: I2TS 2011.

Bernardo David ; da Costa, J. P. C. L. ; Anderson C. A. Nascimento ; Holtz, Marcelo D. ; Amaral, D. ; Sousa Jr., R. T. . A Parallel Approach to PCA Based Malicious Activity Detection in Distributed Honeypot Data. The International Journal of Forensic Computer Science (Impresso), v. 6, p. 8-27, 2011.

Holtz, Marcelo D. ; Bernardo David ; Sousa Jr., R. T. . Building Scalable Distributed Intrusion Detection Systems Based on the MapReduce Framework. Telecomunicacoes (Santa Rita do Sapucai), v. 13, p. 22-31, 2011. (Invited by I2TS 2011 Program Committee)

Program Committees

I am serving (or served) in the Program Committee of the following conferences:

Eurocrypt 2023, 2024.

Asiacrypt 2018, 2021, 2023.

ICDCS 2023.

PKC 2018, 2022.

PODC 2020.

Latincrypt 2021, 2023.

CANS 2017, 2022, 2023.

IWSEC 2019, 2020, 2021, 2023.

NSS 2023.

IFIP SEC 2022.

EISA 2021.

ACISP 2021.

8th ACM SBC 2020.

Provsec 2017, 2018, 2019.

BlockSEA 2018.

IEEE Security & Privacy 2017 (Student Program Committee).

Event Organisation

I have participated in the organisation of the following events. I am grateful to the sponsors for the support!

Contributed Talks Committee member for the PPML workshop co-located with CRYPTO 2023.

Co-Organizer (with Carsten Baum, DTU) of the 1st Summer School on Privacy Preserving Machine Learning in 2022, held at ITU with financial support from the IACR, the Danish Data Science Academy and the Pioneer Center for AI.

Organizer and chair of the session on “Privacy, Regulatory Compliance and High-Assurance for Blockchain Systems and WEB3” at the Digital Tech Summit 2022 in Copenhagen, an event bringing together Danish industry and academia.

I am fortunate to work with the following PhD students and Postdocs:

Esra Yeniaras (Postdoc) – 2023-Present

James Hsin-yu Chiang (PhD Student Co-Supervised with Alberto Lluch, DTU Compute) – Graduated in 2023.

Felix Engelman (Postdoc) – 2022-2022.

Anders Konring (PhD Student) - Expected to Graduate in 2023

Lorenzo Gentile (PhD Student)- Graduated in April 2023

Ravikishore Vasala (Postdoc) - 2020-2023

I am involved (or have been) involved in the projects below. I am grateful to all the sponsors for the support!

Privacy Preserving Solutions for Network Security. Role: Head of Consortium and co-Principal Investigator (with Aarhus University, Monash University, University of Brasilia and University of Washington). Period: 2023-2024. Funding: Global Innovation Network Program of the Danish Ministry of Higher Education and Science.

Accountable Privacy Preserving Computation via Blockchain. Role: co-Principal Investigator (with Aarhus University and Alexandra Institute). Period: 2022-2023. Funding: DIREC.

Time-based Cryptographic Primitives based on Relativistic Delay with Reduced Trust on Satellites. Role: co-Principal Investigator (with Carsten Baum, DTU). Period: 2022-2022. Funding: Protocol Labs.

P2DrEAMM: Privacy Preserving Decentralized Exchange Automatic Market Maker. Role: Principal Investigator. Period: 2022-2022. Funding: CPH Fintech (with co-funding from Monaco Foundry).

Foundations of Privacy Preserving and Accountable Decentralized Protocols. Role: Principal Investigator. Period: 2021-2025. Funding: Sapere Aude Starting Grant from DFF|FNU.

PUMA: Publicly Verifiable Multiparty Computation and Applications. Role: Principal Investigator. Period: 2020-2023. Funding: Project 1 grant from DFF|Thematic Research-Digital Technologies.

TrA2C: Transaction Anonymity and Accountability in Cryptocurrencies. Role: Principal Investigator. Period: 2019-2023. Funding: Project 1 grant from DFF|FNU.

Scalable Blockchain Consensus Protocols. Role: Principal Investigator. Period: 2019-2022. Funding: Concordium Foundation.

S2LEDGES: Single Secret Leader Election on the Edge of Speed. Role: Principal Investigator. Period: 2019-2020. Funding: Protocol Labs.

Efficient Provably Secure Blockchain Protocols And Applications. Role: Principal Investigator. Period: 2018-2020 (terminated on 2019 due to moving from Japan). Funding: Kakenhi Young Scientist research grant from the Japanese Society for Science Promotion (JSPS).

Office: 4C02, IT University of Copenhagen.

Postal Address: Rued Langgaards Vej 7, 2300, Copenhagen, Denmark

Email: bernardo at bmdavid.com

Phone: +4529883541

If you are an ITU student interested in working on cryptography for your bachelor's or master's thesis, I will be happy to work on projects within the broad areas of multiparty computation and blockchain systems. I'm generally interested in the topics described below and specifically interested in this list of Project Ideas. Please contact me (beda snabel-a itu punktum dk) to discuss working on one of these ideas or to propose a new project.

Privacy Preserving Blockchain Applications: Ivestigating provably secure protocols for privacy preserving smart contracts and cryptocurrencies. Specifically, I'm interested in exploring fine-grained proivacy guarantees and auditable protocols compatible with financial regulations.

Scalable Blockchain Consensus: Investigating better blockchain protocols that can reach a global scale, enabling the adoption of blockchain technology for large distributed applications. I want to explore alternatives to Proof-of-Work (e.g. Proof-of-Stake) and sharding/sidechain techniques.

Blockchain Cryptanalysis: Analysing and finding vulnerabilities in blockchain applications with protocols desinged in an ad-hoc way, i.e. without provable security guarantees. I'm interested in finding vulnerabilities in applications that claim privacy guarantees and very efficient consensus.

Efficient Multiparty Computation: Constructing more efficient specific purpose and general purpose multiparty protocols. I am interested in investigating better protocols for computing boolean or arithmetic circuits, as well as exploring specific protocols for applications relevant to industry.

Foundations of Cryptography: Investigating more general and/or efficient constructions for Commitments and Oblivious Transfer with composability guarantees. I am interested in designing more general frameworks for constructing such primitives that potentially yield concretely efficient protocols.

Some interesting resources on cryptography, computer science, mathematics and research in general:

ITU's Center for Information Security and Trust

IACR's Calendar of Conferences/Workshops/Events

Aarhus University Cryptography group

Oded Goldreich's Homepage

"in theory" - Luca Trevisan's blog

A Few Thoughts on Cryptographic Engineering " - Matthew Green's blog

Goedel's Lost Letter and P=NP - Richard Lipton's blog

Tim Gowers's blog

Quantum Frontiers - A blog by the Institute for Quantum Information and Matter @ Caltech

Post-quantum Cryptography - Nice introduction to Post-quantum Cryptography including a comprehensive bibliography

History of Aarhus Crypto Group - Directory of all current and past members of the Aarhus Crypto Group

Synthesizers

I can be found making bleep bloop sounds on an Eurorack synth:

Helicopter Division

I was a proud member of the Aarhus crypto group's Helicopter Division:

Fredagscaféen (Friday Bar)

I've been a volunteer at the Aarhus University's Computer Science Friday Bar

https://www.fredagscafeen.dk/

Chemical Cryptography

I was involved in the creation of one of the most powerful frameworks of modern cryptography: Chemical Cryptography.

Get rid of undesirable computational assumptions and achieve perfect security with the power of C2H6O!

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DOWNLOAD: Chemical OT: On the (Im)possibility of Basing Oblivious Transfer on Chemical Assumptions (presented at the Rump Session of the first Aarhus MPC Workshop

Having Fun in Tokyo

As you may know I spent roughly 7 months in Tokyo while in an internship at NTT's crypto group, of course this gave me more than enough time to explore the city...

Here you can download my TCC 2013 Rump Session presentation about the best spots for having fun in Tokyo.