Spring Semester 2023

Workload characterization in decentralized networks

Simon Jacob

Report

Abstract

After an introduction of a new architecture, there are a bunch of papers that characterize the workload in that new architecture. Some examples include scientific papers focused on: HTTP traffic (1990-2000), user access patterns in the HTTP, sometimes about social media (2000-2010), and microservices (2010-2020). Since decentralized networks have recently become a hot research topic, we plan to extend our current work of dissecting pattern behaviors in the IPFS and Ethereum Swarm networks.

Some of the activities and suggestions for the student working on this project:

Check the distribution of variables (latency, frequency access, etc.)
Provide meaningful and visually attractive visualizations to make sense of large amounts of publicly available data or data captured during the execution of this project
Run nodes or crawl the network to build research datasets.

Finally, from a research perspective, the most attractive thing you can try to achieve is to investigate how you can tune/modify the system to improve some parameters using the knowledge you learned. For example, if you observe that IPFS object search is a long tail distribution and you find that Chord DHT search is the root cause. If you can propose a method to minimize this long tail latency in IPFS, then that would be a very useful systems contribution.

Ideal knowledge and skill set: decentralized and distributed networks, probability and statistics, and visualization techniques.

Reliable decentralized storage

Ahmad Elrouby

Report

We are building a reliable decentralized storage network. Our current solution is an IPFS community network built on the IPFS Cluster solution. Some of the topics you may choose to contribute for this network:

Distributed maintenance and repair
Integrate the network with other storage solutions
Storage load balancing
Plausible deniability, censorship resistance, and privacy in decentralized storage networks.
Develop a solution that does not depend on the IPFS Cluster

Plausible deniability

Kilian d’Eternod

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Distributed maintenance and repair
Integrate the network with other storage solutions
Storage load balancing
Plausible deniability, censorship resistance, and privacy in decentralized storage networks.
Develop a solution that does not depend on the IPFS Cluster

Anonymous Proof-of-Presence Groups for Messaging, Voting and Digital Currency

Amine Belghmi, Michael Greub, Mariem BAccari, Hugo Majerczyk, Kilian Lauener, Dayan Massonnet, Simone Kalbermatter, Victor Nazianzeno-Le Jamtel, Matteo Suez

Report

Abstract

Popular communication tools today either require semi-strong but privacy-invasive identities such as phone numbers to achieve some level of accountability and Sybil attack protection (e.g., WhatsApp or Signal), or use weak identities such as E-mail addresses or pseudonymous public keys (e.g., Bitcoin) but lose any fair, “person-centric” form of accountability or Sybil attack protection. The DEDIS lab is developing a new, human-centric “proof-of-personhood” (PoP) solution to this problem leveraging physical presence at real-world events to provide privacy-preserving but accountable, Sybil-protected identities.
This project will prototype a minimalistic but highly robust and usable proof-of-presence group communication app for mobile devices. The app will enable anyone to organize an in-person event, and take a secure “roll-call” at that event to connect with attendees and give each a one-per-person digital membership token. With these tokens, attendees can message each other, participate in an election or exchange currency without needing any strong identities (phone numbers etc), but with the ability to hold all participants accountable.

Optimizing Front-Running Protection

Louis Bettens

Abstract

Front-running attacks, which benefit from advanced knowledge of pending transactions, have proliferated in the cryptocurrency space since the emergence of Decentralized Finance(DeFi). Front-running causes devastating losses to honest participants—estimated at $280M each month—and endangers the fairness of the ecosystem. Thus, there is an urgent need to develop tools that can be deployed with reasonable overhead in the real world to mitigate the attack.

The DEDIS lab is developing a general architecture named Flash Freezing Flash Boys (F3B) that systematically mitigates front-running attacks for all smart contracts at once at the blockchain architecture level. This project aims to implement different advanced crypto primitives on the DEDIS blockchain for F3B to reduce the latency overhead and increase throughput performance.

Analyzing Rationality on Blockchain

Liam Mouzaoui

Abstract

Many blockchain systems adopt rationality assumptions to ensure the security of the system. Rationality assumptions tell that any node would maximize its profit in a blockchain system. For example, a miner is incentivized to work on the current longest chain in Bitcoin. This strategy can improve his chance of producing the future longest chain, thus maximizing his reward. The Ethereum Proof-of-Stake consensus adopts the deposit-slashing protocol to disincentivize any node that double signs two blocks with the same height.

Such an incentive mechanism seems to provide additional security to the system. However, it may be that the argument only limits the system without considering the outside world. Thus, an irrational behavior within the system may be rational when analyzing rationality in the context of the larger ecosystem.

This project aims to study the rationality assumption. Does it increase the system’s actual security? If so, can this increase in security be quantified? If not, can we develop attacks that defeat the rationality assumption in some (or many) blockchain system(s)?

Humanitarian Aid Financial Network

Hana Farid and Jiechen Zhang

Report

Abstract

Humanitarian Aid Organizations are interested in issuing digital assets to people in need (beneficiaries). However, existing infrastructure for digital assets present significant risks to the privacy and the personal safety of beneficiaries. The DEDIS lab has devised a new set of protocols for a permissioned infrastructure to allow for beneficiaries to transact securely and without Internet connectivity. In this project, you will be taking on building out the necessary infrastructure to implement and evaluate these sets of protocols.

The applicant must have knowledge of modern cryptography, such as zero-knowledge proofs. Knowing about and having worked with Multi-Party Computation is preferred.

Resilient BFT State Machine Replication

Abstract

State machine replication (SMR) is a distributed systems abstraction, which allows a group of nodes to replicate the state, in a strongly consistent manner, while being resilient to a fraction of node failures. Byzantine fault tolerant (BFT) SMR is a class of SMR algorithms, where the nodes can display byzantine behaviors (nodes can deviate from the correct protocol description in arbitrary ways).

Existing BFT SMR algorithms make a tradeoff between performance and resilience. In the performance end, algorithms such as Hotstuff aim at delivering high performance, while losing liveness in the face of targeted DDoS attacks. In the resilience end, algorithms such as VABA deliver resilience to DDoS attacks but have quadratic message complexity and low performance in the common synchronous case. In this project, we aim at addressing this tradeoff by proposing algorithms and system designs to achieve both performance and DDoS resilience.

This project will leverage random exponential backoff (REB) to address this tradeoff. We will first focus on how to adapt REB to BFT SMR algorithms, to strengthen the robustness guarantees of the resulting SMR algorithm. Second, we will focus on the design and implementation of the new algorithm. Finally, we will do an experimental analysis of the resulting system, to showcase its resiliency properties.