Talks and presentations

Blockchain in Fintech - An Overview

October 07, 2022

Tutorial, Vietnam Institute for Advanced in Mathematics, Hanoi, Vietnam

Blockchain technology is already being explored in a wide number of Fintech sectors. This talk will present an overview of the Fintech ecosystem and the topics that can be investigated as a result of the new digital advances brought forth by blockchain. We will first present the fundamentals of blockchain, and then how blockchain technology transforms the Fintech industry. Based on a list of selected characteristics, we will present a taxonomy of blockchain platforms. We then talk about the use cases for each of the Fintech ecosystem’s verticals, including Central bank digital currency (CBDC). These use cases are prevalent in public blockchain ecosystems and are upending established financial transaction protocols. Finally, we will mention some challenges of using blockchain technology in Fintech.

Security & Privacy on Blockchains

August 04, 2022

Tutorial, The 9th Vietnam Summer School of Science, Quy Nhon, Vietnam

This talk will present an overview of security and privacy issues on blockchains. I also provide some open research questions in this talk.

Synthetic Data Generation and Evaluation

October 21, 2020

Talk, The 2020 Serene-risc Workshop on The State of Canadian Cybersecurity, Online (https://www.serene-risc.ca/en/events/workshops/2020-serene-risc-workshop)

Data privacy has recently become a hot topic in the news thanks to failures in security and concerns about how companies are using the personal data they collect about their customers or users. Facebook, for instance, faced scrutiny over its handling of consumer data both in the U.S. and in the U.K. Facing the above issues, the generation of synthetic data is becoming a fundamental task in the daily life of any organization. Synthetic data is directly and separately generated from an original data. The generated data should be realistic in certain aspects, like format, distribution of attributes, relationship among attributes, etc; and could provide the similar results when performing data analytics on both datasets. In this presentation, we will first present recent research to generate synthetic data, and then empirical methods to evaluate the similarity of the generated data.

Algebraic Differential Fault Attacks on SIMON Lightweight Block Ciphers

August 29, 2019

Talk, Canadian Institute for Cybersecurity, UNB, Fredericton, Canada

Algebraic differential fault attack (ADFA) is an attack in which an attacker combines a differential fault attack and an algebraic technique to break a targeted cipher. In this paper, we present three attacks using three different algebraic techniques combined with a differential fault attack in the bit-flip fault model to break the SIMON block cipher. First, we introduce a new analytic method which is based on a differential trail between the correct and faulty ciphertexts. This method is able to recover the entire master key of any member of the SIMON family by injecting faults into a single round of the cipher. In our second attack, we present a simplified Grobner basis algorithm to solve the faulty system. We show that this method could totally break SIMON ciphers with only 3 to 5 faults injected. Our third attack combines a fault attack with a modern SAT solver. By guessing some key bits and with only a single fault injected at the round T - 6, where T is the number of rounds of a SIMON cipher, this combined attack could manage to recover a master key of the cipher. For the last two attacks, we perform experiments to demonstrate the effectiveness of our attacks. These experiments are implemented on personal computers and run in very reasonable timing.

A new multisignature scheme with public key aggregation for blockchain

August 27, 2019

Talk, Fredericton Convention Centre, Fredericton, NB,Canada

A multi signature scheme allows a group of signers to produce a joint signature on a common message, which is more compact than a collection of distinct signatures from all signers. Given this signature and the list of signers’ public keys, a verifier is able to check if every signer in the group participated in signing. Recently, a multisignature scheme with public key aggregation has drawn a lot of attention due to their applications into the blockchain technology. Such multisignatures provide not only a compact signature, but also a compact aggregated public key, that is both the signature size and the public key size used to verify the correctness of the signature are independent from the number of signers. This is useful for a blockchain because of its duplication over a distributed network, and thus it is required to be as compact as possible. In this paper, we introduce a new multisignature scheme with such a feature. Our scheme is proven secure under the Decisional Diffie-Hellman assumption. In addition, in the presence of rogue key attacks, the security of our scheme is proven in the plain public key model.