Bernardo David

Email me: bernardo at

About Me

I am an Assistant Professor at the Tokyo Institute of Technology. I hold a Ph.D. in Computer Science from Aarhus University obtained in 2017 under the supervision of Ivan Damgård and Jesper Buus Nielsen. I have also been a long term visitor at the NTT Secure Plaftorm Laboratories working with Tatsuaki Okamoto and Masayuki Abe and at the Cryptography Group at Bar Ilan University working with Yehuda Lindell.

→Download my full CV

My Research

I'm interested in a broad range of topics in cryptography and information theory. My current focus is on theoretical and practical aspects of secure multiparty computation and blockchains/cryptocurrencies. Previously I have worked on coding based cryptography, structure preserving signatures, network intrusion detection, practical user authentication, online banking and cryptographic protocols in general.

→My Google Scholar Profile and my DBLP



Here you can find a list of my publications in refereed journals and conferences. You can also find a partial list at my DBLP or Google Scholar Profile.

Conference Papers

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:

Asiacrypt 2018

Provsec 2018

PKC 2018

CANS 2017

Provsec 2017

IEEE Security & Privacy 2017 (Student Program Committee)

I have been a sub-reviewer for the following conferences and journals: ACISP 2013, ACNS 2015, Asiacrypt 2014, Asiacrypt 2105, Asiacrypt 2016, Asiacrypt 2017, ACM CCS 2016, ACM CCS 2017, Crypto 2012, Crypto 2014, Crypto 2017, Eurocrypt 2012, Eurocrypt 2015, Eurocrypt 2018, Financial Crypto 2015, INSCRYPT 2013, ISIT 2016, IET Information Security, IEEE Transactions on Information Security and Forensics, Journal of Cryptology, MFCS 2016, PKC 2014, PKC 2016, PODC 2017, SCN 2014, SCN 2016, TCC 2012 and TCC 2015

Crypto & Research Links

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

The MPC Lounge - All about the practical and theoretical aspects of secure multiparty computation.

IACR's Calendar of Conferences/Workshops/Events

Ivan Damgård's Homepage

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

Contact Me

Address: Department of Computer Science, Aabogade 34, 8200 Aarhus, Denmark. Office: Nygaard 284

Email: bernardo at

Phone: (+45)29883541

Fun & Hobbies

Helicopter Division

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

Fredagscaféen (Friday Bar)

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

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!


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.