Schedule for: 20w2246 - Data Science on Blockchains

Note: the Lecture rooms are available after 16:00.

Beverages and a small assortment of snacks are available in the lounge on a cash honour system.

A buffet breakfast is served daily between 7:00am and 9:00am in the Vistas Dining Room, the top floor of the Sally Borden Building. Note that BIRS does not pay for meals for 2-day workshops.

A brief introduction to BIRS with important logistical information, technology instruction, and opportunity for participants to ask questions.

Blockchain and Data Science both represent nascent fields. The intersection of the two is even less explored. In this talk we will delineate between the application of Data Science for the understanding of Blockchain networks versus the application of Blockchains to the practice of Data Science; and present an example of each. First, we discuss how simulation modelling can be used to create a comprehensive in-silico laboratory for understanding the behaviour and characteristics of Blockchain networks. Second, a vision of how blockchain and simulation modelling can be combined to enable participatory evidence-based decision support in an infectious disease context. Profile: https://blockchain.lab.yorku.ca/second-page/marek-laskowski/ https://www.linkedin.com/in/laskowskimarek/

A buffet lunch is served daily between 11:30am and 1:30pm in the Vistas Dining Room, the top floor of the Sally Borden Building. Note that BIRS does not pay for meals for 2-day workshops.

Meet in foyer of TCPL to participate in the BIRS group photo. The photograph will be taken outdoors, so dress appropriately for the weather. Please don't be late, or you might not be in the official group photo!

Kaiwen Zhang (https://fuseelab.github.io/) is an Assistant Professor in the Department of Software and IT Engineering at ÉTS Montréal (University of Québec). Previously, he was an Alexander von Humboldt postdoctoral fellow in Computer Science at the TU Munich (2015-2017) and a member of the Middleware Systems Research Group. Dr. Zhang obtained his B.Sc. and M.Sc. at McGill University in Montréal and his Ph.D. at the University of Toronto. His research interests include blockchain technologies, publish/subscribe systems, massively multiplayer online games, and software-defined networking. Dr. Zhang's expertise lies at the intersection of distributed systems, networking, and data management. His research is published in premier distributed systems conferences such as IEEE ICDCS and ACM Middleware.

Bitcoin users can offer fees to miners who record their transactions in the Blockchain. We document high variation of bitcoin fees, not only over time, but also within blocks. Further, the blockchain rarely runs at capacity, even though fees tend to be higher when blocks are fuller, so miners appear to be leaving money on the table. We present a simple model of price discrimination to explain our results. We note that mining pools facilitate collusive equilibria, and estimate that they have extracted least 200 million USD a year in excess fees by making processing capacity scarce.

A buffet dinner is served daily between 5:30pm and 7:30pm in the Vistas Dining Room, the top floor of the Sally Borden Building. Note that BIRS does not pay for meals for 2-day workshops.

The design of the difficulty adjustment algorithm (DAA) of the Bitcoin system is vulnerable as it dismisses miners' strategic responses to policy changes. We develop an economic model of the Proof-of-Work based blockchain system. Our model allows miners to pause operation when the expected reward is below the shutdown point. Hence, the supply of aggregate hash power can be elastic in the cryptocurrency price and the difficulty target of the mining puzzle. We prove that, when the hash supply is elastic, the Bitcoin DAA fails to adjust the block arrival rate to the targeted level. In contrast, the DAA of another blockchain system, Bitcoin Cash, is shown to be stable even when the cryptocurrency price is volatile and the supply of hash power is highly elastic. We also provide empirical evidence and simulation results supporting the model's prediction. Our results indicate that the current Bitcoin system might collapse if a sharp price reduction lowers the reward for mining denominated in fiat money. However, this crisis can be prevented through the upgrading of DAA. URL: https://ssrn.com/abstract=3410460 Slides: https://drive.google.com/file/d/1iUdxKeZkz6xP0CCMDiEGVQyiYU3LIvNo/view

Proliferation of cryptocurrencies (e.g., Bitcoin) that allow pseudo-anonymous transactions, has made it easier for ransomware developers to demand ransom by encrypting sensitive user data. The recently revealed strikes of ransomware attacks have already resulted in significant economic losses and societal harm across different sectors, ranging from local governments to health care. Most modern ransomware use Bitcoin for payments. However, although Bitcoin transactions are permanently recorded and publicly available, current approaches for detecting ransomware depend only on a couple of heuristics and/or tedious information gathering steps (e.g., running ransomware to collect ransomware related Bitcoin addresses). To our knowledge, none of the previous approaches have employed advanced data analytics techniques to automatically detect ransomware related transactions and malicious Bitcoin addresses. By capitalizing on the recent advances in topological data analysis, we propose an efficient and tractable data analytics framework to automatically detect new malicious addresses in a ransomware family, given only a limited records of previous transactions. Furthermore, our proposed techniques exhibit high utility to detect the emergence of new ransomware families, that is, ransomware with no previous records of transactions. Using the existing known ransomware data sets, we show that our proposed methodology provides significant improvements in precision and recall for ransomware transaction detection, compared to existing heuristic based approaches, and can be utilized to automate ransomware detection.

2-day workshop participants are welcome to use BIRS facilities (Corbett Hall Lounge, TCPL, Reading Room) until 15:00 on Sunday, although participants are still required to checkout of the guest rooms by 12 noon. There is no coffee break service on Sunday afternoon, but self-serve coffee and tea are always available in the 2nd floor lounge, Corbett Hall.