Summary

A decentralized system is one that works when no single party is in charge or fully trusted. This course teaches decentralized systems principles while guiding students through the engineering of their own decentralized system featuring messaging, file sharing, encryption, and blockchain concepts.

Content

Keywords

distributed systems, decentralized systems, security, privacy, anonymity, cryptography, gossip, consensus, swarming, blockchain, cryptocurrency

Learning Prerequisites

Required courses

• COM-208 Computer networks

Recommended courses

• CS-206 Parallelism and concurrency
• COM-301 Computer security
• CS-323 Introduction to operating systems 

Important concepts to start the course

Students must already be highly competent at programming and debugging in a high-level systems programming language such as Java, C#, or Go.  Programming exercises will be in Go, but students already well-versed and experienced in programming with comparable systems languages should be able to pick up Go during the course.

Students should have both solid foundational knowledge of how networks function, and some experience actually writing network programs, e.g., TCP/IP programming using the Sockets API.

Learning Outcomes

By the end of the course, the student must be able to:

• Implement decentralized systems via hands-on coding, debugging, and testing
• Design practical distributed and decentralized systems
• Design effective testing strategies for distributed and decentralized systems

Transversal skills

• Set objectives and design an action plan to reach those objectives.
• Identify the different roles that are involved in well-functioning teams and assume different roles, including leadership roles.
• Assess progress against the plan, and adapt the plan as appropriate.
• Take account of the social and human dimensions of the engineering profession.

Teaching methods

Lectures: The course's lectures will present and discuss challenges, known techniques, and open questions in decentralized system design and implementation. Lectures will often be driven by examination of real decentralized systems with various purposes in widespread use the past or present, such as UseNet, IRC, FreeNet, Tor, BitTorrent, and Bitcoin. Throughout the course we will explore fundamental security and usability challenges such as decentralized identification and authentication, denial-of-service and Sybil attacks, and maintenance of decentralized structures undergoing rapid changes (churn).

Labs: During the semester, students will develop a small but usable peer-to-peer communication application that reflects a few of the important design principles and techniques to be explored in the course, such as gossip, distributed hash tables, consensus algorithms, and cryptocurrencies. The labs will designed so that solutions can initially be tested individually on private, virtual networks running on one machine, then tested collectively by attempting to make different students' solutions interoperate on a real network.

Warning: This course is extremely programming-intensive. Students should be strong and confident in their programming skills in general, and be willing to spend substantial time outside of class debugging difficult distributed concurrency bugs and other challenges.  TAs will be available to help at the exercise sessions, but they will not solve your problems or debug your code for you.

Expected student activities

Students will be expected to attend lectures to understand the concepts needed for the course, but the main workload will be actual hands-on programming assignments, which the students will perform on their own during the first part of the course and in teams during the final project-oriented part of the course.

Assessment methods

• Programming assignment grading (evaluating function, performance, correctness and implementation quality): 50%
• Final project grading and associated oral exam (accounting for scope, appropriateness, implementation quality, testing and documentation): 50%

Supervision

Resources

Virtual desktop infrastructure (VDI)

No

Moodle Link

• https://go.epfl.ch/CS-438