Lectures Publications Theses Events


Challenge Task Winner Blockchain HS 2021

The winning group is: Reto Ehrensperger and Christian Rutzer

Reto Ehrensperger and Christian Rutzer implemented QuoteNFT, a platform to trade NFT quotes. The trading happens on a smart contract and is fully decentralized. Their project uses Vue.js for the frontend, node and express with TypeScript for the backend, and MetaMask to connect to Ethereum. Their QuoteNFT platform uses Traefik as a reverse proxy and docker-compose to orchestrate the services.

The price is sponsored by Axelra, a tech venture builder that accelerates digital business models (Linkedin announcement).

Important dates: (always check https://unterricht.rj.ost.ch)

Blockchain (BlCh)

(Formerly known as Advanced Distributed Systems & Blockchain - ADSB)

0124.09.2021Admin, Challenge Task, Repetition DS1 (part 1) - no exercises
0201.10.2021NFT Introduction, Repetition DS1 (part 2)
0308.10.2021Ethereum and Solidity, Repetition DS1 (part 3)
0415.10.2021NFT Details
0522.10.2021P2P and DHTs
0629.10.2021DeFi Introduction
0705.11.2021DeFi DEX, Interview with Marcel Harmann
0812.11.2021Algorithms for Distributed Systems 1, DeFi NFT Markets
0919.11.2021HTLCs, Cross-chain Atomic Swaps, and Algorithms for Distributed Systems 2
1026.11.2021WebRTC, Layer 2 Solutions
1103.12.2021Security Considerations, Layer 2 Use Cases, Interview with Christian Killer and Guilherme Sperb Machado
1210.12.2021Exam preparation, NFT Markets, and Smart Contract Testing
1317.12.2021Live: Q&A (from 08:10 – 08:55), Challenge Task Presentations
1424.12.2021Challenge Task Award Winner Announcement - Online, no lectures

(those are preliminary topics, may be subject to change)

Online Lectures & Exercises

Due to COVID, the Blockchain (BlCh) lecture will be online. The lecture videos will up uploaded during the week before the lecture on Fridays at 08:10. The length of the videos will be ~ 80 - 100 minutes (2 x 45min. lectures) divided into segments. The news segment (~10min) will cover news around the topics blockchain and distributed systems and are not part of the exam. It should serve as on overview of current topics in this field.

For the exercises, I will be available online on Friday from 10:10 - 16:50 on MS Teams. Team code: pq6c050. Please contact me if you have any questions regarding the challenge task or also just to say Hi :) During exercises, you can work on your challenge task.

The online lectures and PDFs can be accessed from outside (also on Youtube), the exercise and admin material only with VPN.

Lecture Content

Lecture 1

Admin News
Repetition DS1 part1

The admin part gives an overview over this lecture and presents the challenge task for this course (Slides: BlCh-HS21-01-Admin.pdf). The second video (news) discusses crypto company regulations in the US, and the DNS alternative HNS (Handshake) and ENS with IPFS (Slides: BlCh-HS21-01-News.pdf). The third video starts with the repetition of DS1 (Slides: BlCh-HS21-01-DS1-part1.pdf). [82min]

Lecture 2

Admin News
NFT Introduction Repetition DS1 part2

The admin part is about the challenge task and the groups (Slides: BlCh-HS21-02-Admin.pdf). The second video (news) discusses blockchain and energy efficiency, NFTs, and China's ban of crypto currencies (Slides: BlCh-HS21-02-News.pdf). The third video introduces NFTs on a high level, to provide an overview over potential use cases for the challenge task (Slides: BlCh-HS21-02-NFT.pdf). The fourth video continues with the repetition of DS1 (Slides: BlCh-HS21-02-DS1-part2.pdf). [88min]

Lecture 3

Admin News
Repetition DS1 part3 Ethereum and Solidity

The admin part is about the challenge task and the groups (Slides: BlCh-HS21-03-Admin.pdf). The news video discusses many topics, such as lost or stolen coins (Slides: BlCh-HS21-03-News.pdf). The third video finishes with the repetition of DS1 (Slides: BlCh-HS21-03-DS1-part3.pdf). The fourth video shows Solidity with examples (Slides: BlCh-HS21-03-ETH.pdf. [126min]

Lecture 4

Admin News
NFTs with Ethereum and Solidity

The admin part is about the challenge task and the groups (Slides: BlCh-HS21-04-Admin.pdf). The news video discusses the mining shift to the US as well as the attacks on OVH and Azure. (Slides: BlCh-HS21-04-News.pdf). The third video shows NFT examples with Solidity (Slides: BlCh-HS21-04-NFT.pdf, nft.sol, erc20.sol). [72min]

Lecture 5

Admin News
NFTs with Ethereum and Solidity

The admin part is about the lecture content (Slides: BlCh-HS21-05-Admin.pdf). The news video discusses the BTC all-time high and Stripe hiring a crypto team. (Slides: BlCh-HS21-05-News.pdf). The third video introduces fully distributed systems and DHTs (Slides: BlCh-HS21-05-P2P.pdf). [94min]

Lecture 6

Admin News
DeFi Introduction

The admin part is about the lecture dates and the new SG I rules (Slides: BlCh-HS21-06-Admin.pdf). The news video discusses the Internet outage in Sudan and the Cream Finance Flash Loan Hack. (Slides: BlCh-HS21-06-News.pdf). The third video introduces decentralized finance (DeFi) (Slides: BlCh-HS21-06-DeFi.pdf). [73min]

Lecture 7

Admin News
DeFi Details Interview with Marcel Harmann, Co-Founder of DeFi Suisse

The admin part is about the challenge task hand-in on the 04.11.2021, 23:59 (CET) (Slides: BlCh-HS21-07-Admin.pdf). The news video discusses best practices for NTP server, hacking DeFi, and NFTs (Slides: BlCh-HS21-07-News.pdf). The third video is the interview with Marcel Harmann from DeFi Suisse who talks about THORWallet (disclaimer: I'm also involved in this project). The fourth video looks into DeFi mechanisms, such as swaps and liquidity providing on a decentralized exchange (DEX) (Slides: BlCh-HS21-07-DeFi.pdf). [113min]

Lecture 8

Admin News
NFT Implementation Details Algorithms for P2P Systems

The admin part is about the challenge task and the lecture topics (Slides: BlCh-HS21-08-Admin.pdf). The news video is about Bitcoin Taproot and the current crypto market all time high (Slides: BlCh-HS21-08-News.pdf). The third video answers how a decentralized NFT market place can be implemented (Slides: BlCh-HS21-08-NFT2.pdf, market.sol). The fourth video introduces Bloom filters and Merkle trees/proofs BlCh-HS21-08-Algo.pdf). [81min]

Lecture 9

Algorithms for P2P Systems 2 Hashed Time Lock Contracts and Atomic Swaps

The news video is about Bitcoin Taproot and the current crypto market dip (Slides: BlCh-HS21-09-News.pdf). The second video introduces two mechanisms that can be used in systems with consistent hashing (Slides: BlCh-HS21-09-P2P-2.pdf). The third video dives into Hashed Time Lock Contracts (HTLC) and Atomic Swaps that can be used to do fully decentralized cross-chain crypto currency swaps BlCh-HS21-09-HTLC.pdf). [84min]

Lecture 10

Admin News
Layer 2 - Payment Channels WebRTC

The admin part is about the lecture topics (Slides: BlCh-HS21-1-Admin.pdf). The news video is about load balancing, crypto regulations, and THORWallet (Slides: BlCh-HS21-10-News.pdf). The third video is about payment channels and scaling solutions (Slides: BlCh-HS21-10-Payment-Channels.pdf). The forth video dives into WebRTC BlCh-HS21-10-WebRTC.pdf). [127min]

Lecture 11

Admin (correct hand-in date: 16.12.2021, not 10.12) News Interview Christian Killer
Layer 2 - Payment Channel Use Cases Security Considerations Interview Guilherme Sperb Machado

The admin part is about the challenge task hand-in on the 16.12.2021, 23:59 (CET) and the q-feedback (Slides: BlCh-HS21-11-Admin.pdf). The news video is about the swiss crypto stamp, an article about proof-of-stake vs. proof-of-work, and more NFTs (Slides: BlCh-HS21-11-News.pdf). The third video is about use cases for payment channels (Slides: BlCh-HS21-11-Micro-Payments2.pdf). The forth video is about security considerations BlCh-HS21-11-Security.pdf). The fifth video is the interview with Christian Killer, a blockchain researcher, while the sixth video is the interview with Guilhereme Sperb Machado, the founder of AxLabs. [77min]

Lecture 12

Admin (Exam Preparation) News
NFT Market - Security Swaps and Smart Contract Testing

The admin part is about the exam preparation (Slides: BlCh-HS21-12-Admin-Exam-Prep.pdf, ADSB_Exam_2020-HS_v2.pdf). The news video is about DNS bug hunting, TOR attacks, Linux namespaces, and the Swiss crypto stamp (Slides: BlCh-HS21-12-News.pdf). The NFT market lecture show a security issue with the contracts showed in lecture 8 and how to fix it (Slides: BlCh-HS21-12-NFT-Markets.pdf, market2-1.sol). The Swap lecture is about impermanent loss and how smart contracts can be tested (Slides: BlCh-HS21-12-Swaps.pdf. [89min]

Lecture 13

Admin (Challenge Task Presentations)

The admin part is about the challange task presentations. Please fill in the following doodle at what time you will present your challenge task results. (Slides: BlCh-HS21-13-Admin.pdf. The news video is about NFT markets, Web3, HTTP/3, and THORWallet (Slides: BlCh-HS21-13-News.pdf) [20min]

Lecture 14


The news video is about an article of the biggest letdowns in crypto, my personal highlight in crypto: THORWallet (no investment advice, I'm involved in this project), and the Blockchain HS21 Challenge Task Winners (Slides: BlCh-HS21-14-News.pdf) [13min]

Challenge Task HS 2021

This semester's challenge task (CT) is the design and implementation of an application including NFTs. Ideally, the application is a decentralized application (DApp).


All requirements below must be met in order to pass this course.

  1. A working prototype for your use-case
  2. Use latest stable releases of chosen libraries and frameworks
  3. An NFT stored on a public blockchain (can be testnet)
  4. Transfer of an NFT triggered directly or indirectly via the frontend/backend (can be testnet)

Deliverables: 04.11.2021, 23:59 (CET) first hand-in of your initial version of the frontend/backend/NFT (initial version, does not need to run). Second hand-in: 16.12.2021, 23:59 (CET) - well documented infrastructure (Readme.md or can be slides) and the source code (github/gitlab or similar) via invite or email to thomas.bocek-at-ost.ch (alternatively, use: thomas.ost-at-bocek.ch). The code and configuration should be easy to read and/or well documented. For the presentation on the 17.12.2021, you should show the architecture, components, and design decisions in 10-15 min, a demo in 5-10 min, and the Q&A will be 20min via MS Teams. After your presentation, you need to handin your PDF presentation.

You are allowed to use any language, framework, and platforms. However, the supervisors are familiar with those: Java, Golang, JavaScript, Linux, Ethereum.


There will be groups of 2-3 for the challenge task. During the challenge task, the group shall meet every week during exercise hours to work on the task and discuss the next steps. The groups shall utilize their homework times to work on the CT, besides the exercise time slots assigned on Friday. You do not have be present at the exercises. The groups shall determine and set-up an internal project plan and shall distribute the workload so that each group member gets a fair load of work. Group results will be only accessible via VPN.

NrName 1Name 2Name 3ProjectMilestone 1SourceSlidesVideo
1Julia F.David K.-NFT Tweetsgroup1.zipgroup1.pdfgroup1.mp4
2Zvonimir S.Simon C.-NFT Marketgroup2.zipgroup2.pdfgroup2.mp4
3Michel M.Benny V.Moritz S.NFT Redditgroup3.zipgroup3.pdfgroup3.mp4
4Samuel L.Tim W.Rolf O.NFT Creatergroup4.zipgroup4.pdfgroup4.mp4
5Andy P.Pascal K.-Image Auction NFTgroup5.zipgroup5.pdfgroup5.mp4
6Ruwen F.Igor C.-NFT Lotterygroup6.zipgroup6.pdfgroup6.mp4
7Severin G.Marco M.Severin A.GPS-NFTgroup7.zipgroup7.pdfgroup7.mp4
8Simon H.Marius Z.Janis W.NFTrophygroup8.zipgroup8.pdfgroup8.mp4
9Christian R.Reto E.-QuoteNFTgroup9.zipgroup9.pdfgroup9.mp4
10Philipp E.Joel S.-Beer Stamp NFTgroup10.zipgroup10.pdfgroup10.mp4
11Linard V.Robin F.-NearShare (with additional req.)group11.zipgroup11.pdfgroup11.mp4