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Department of Informatics - Communication Systems Group

Challenge Task 2020

This semester's Challenge Task (CT) is to implement a Decentralized Application (DApp) deployed on the Ethereum blockchain. The choice of application to be implemented depends on the group's choice, which can range from gambling systems, file transfer applications, or any decentralized system. The groups shall inform the teaching assistants on the topic and discuss the feasibility of the proposal. One can check past CTs (e.g., Challenge Task 2017Challenge Task 2018, and Challenge Task 2019) to have an idea about examples of applications.

Even though the groups are free to choose the application to be implemented as a DApp, all groups must ensure that all requirements are met and follow the defined deadlines. The necessary information to fully accomplish the CT, assumptions, libraries, tools, and impact on the grade are detailed in the next sections and on the CT Formal Description (PDF, 157 KB).


Each CT group is free to decide on the design of the DApp, for example, how the communication with the on the use-case and how to interact with the system. However, for each CT group, the following key requirements need to be met:

  1. The core functionality must be implemented and executed entirely within Smart Contracts (SC).
  2. The SC must implement an economic aspect, e.g., a payment system, incentives, gambling, or any economy-related functionality.
  3. The user must interact with the DApp via a Graphical User Interface (GUI), for example, a Web-based one.
  4. The group must deliver a self-contained report documenting the SC, its operation, and the source code.

Further suggestions include:

  • The solution may use existing libraries and code, but those must be allowed to be published under APL or another comparable open software license.
  • The final report shall document the application, and its operation, mainly with all the details needed to understand the solution to be shown at the presentation and demo time slot. The report should contain approximately 5-10 pages, and be written in a technical manner.
  • The source code must be well documented and contain installation guidelines.


The following facts may be assumed:

  • The Smart Contract can be deployed in a private testnet or in the Ropsten testnet.
  • You can use just one node (Ganache, Parity or Geth client) with multiple addresses.

Note: Further assumptions, which are not restricting these assumptions above, can be made according to each group's approach.

Libraries and Tools

The items below represent supporting libraries, tools, or references that are recommended to be taken into consideration.


  • The groups shall be balanced in expertise and work-wise. Every group shall have at least one development expert. During the CT, 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 Thursdays.
  • The groups shall determine and set-up an internal project plan with the overall milestones, responsibilities, and timings provided therein.
  • Distribute the workload so that each group member gets a fair load of work (a fair P2P load balancing, no free-riding!) and make sure activities can run in parallel (non-blocking).
  • You can use your own laptop and/or the computers in room BIN 1.D.12.
  • Do not miss the opportunity of discussing details with your group‘s supervisor; he/she might give you useful hints.
  • A midterm meeting/presentation to the supervisors is expected from the group in order to update them with the development of the application.

Groups and Support

During the challenge task each group will be able to ask questions and get support from their supervisors:

The groups that not discussed or sent their topics to the teaching assistants  are encouraged to contact them as soon as possible.

# Group Name Participants Topic
1 Bitcoin
  1. Ankan Ghosh
  2. Saiteja Reddy
  3. Badrie Leonardas Persaud

DAO for Development of Public Infrastructure

2 Ethereum
  1. Fabian Küffer
  2. Pascal Kiechl
  3. Anna Jancso
Tokenized Roulette with Gambling System
3 Monero
  1. Lutharsanen Kunam
  2. Dario Bugmann
  3. Lundrim Azemi
  4. Matthias Luethi
Smart Contract-based Betting Platform
  1. Nicolas Spielmann
  2. Michael Bucher
  3. Marius Högger
  4. Claudio Brasser

Trading card / Loot-box System

5 Litecoin
  1. Noah Chavannes
  2. Yves Rutishauser
  3. Calvin Falter
  4. Severin Siffert
Decentralized eBay-like Marketplace
6 Stellar
  1. Jeremy Kubrak
  2. Matej Jakovljevic
  3. Marc Zwimpfer

Slot Machine with Increasing Ether Jackpot

7 ZCash
  1. Mariann Burk
  2. Mervin Cheok
  3. Claudia Jurado Santos
  4. Daniel Demeter
DNS Server on a Smart Contract

Presentation and Evaluation

Challenge Task (CT) presentations and demonstrations will take place on Thursday 14.05.2020 and Thursday 28.05.2020 from 14:00 to 15:45 hours. On these dates, the groups will present and demonstrate their results, which will be evaluated by the class. Presentations and demos on these two dates will take place in room BIN 2.A.10

  • Each group will have ~20 minutes for presenting their design and to demonstrate the working application (roughly 10 min presentation and 10 min demo). The presentation shall include slides. For the demonstration, the group must run one (or more) use-cases of your application, showing that it meets the defined requirements and successfully implements the proposal. Most of the demonstration, though, will be done using the machine connected to the projector(s), so all the people in the classroom can see what is going on. Ideally, it is the same machine that will run the slide presentation. The presentation will be performed via screen-sharing. Thus, one person of the group will need to share their screen and present the presentation and or the demo. Note that it is expected that everybody contribute towards the presentation and demo in a organized fashion.
  • Make sure that everything will work for your demo! Test everything beforehand with given conditions, especially the blockchain/mining. If a group fails to present within its time window, it will be disqualified.
  • Remember that the audience will not only be interested in seeing whether or not your Smart Contract works, but more specifically, how the designed mechanisms (e.g., SC communication, random number generation, betting, and so on) for your DApp work behind the scenes.
  • After the presentations, each group will be evaluated by all of the other groups. The evaluation will work in a decentralized and democratic manner as follows: each group will rank the presentation and DApp of other groups. The CSG members as a group will also rank the presentations, which will serve as a tiebreaker in case that no consensus is reached from the group's ranking. The following criteria should be taken into consideration to rank the groups: software design and implementation (overall design, and usability), teamwork, presentation, and demonstration of the solution. Each position in the ranking awards a defined amount of points, which will be summed up for each group. For example, the 1st position in the ranking receives n points while the n position receives 1 point, where n is equal to the number of groups minus one. It should be noted that the group does not rank itself. The results of the ranking will be collected and disclosed after the last presentation. The winning group (i.e., the one who sums more points) will receive a prize and the "BCOLN Challenge Champion 2020" award.
  • Each group shall hand-in by e-mail ( the report and source-code of the Smart Contracts until 14.05.2020 - 23:58

CT Grading Impact

The CT grade will impact in the final written exam grade in the following manner:

  • All the four CT requirements met (0 missing requirements):
    • No overall grade reduction
  • Three CT requirements met (1 missing requirements):
    • 0.5 point grade reduction in the final written exam
  • Two requirements met (2 missing requirements):
    • 1.0 point grade reduction in the final written exam
  • Only one requirement met (3 missing requirements):
    • 1.5 point grade reduction in the final written exam
  • No requirement met (4 missing requirements):
    • 2.0 point grade reduction in the final written exam
  • If grade equals or below 4.0:
    • No grade reduction
Grading Table Example


Fulfilment of the Requirements

Requirement / Group

1 - Bitcoin

2 - Ethereum 3 - Monero 4 - NEO 5 - Litecoin 6 - Stellar 7 - ZCash

RQ 1

RQ 2

RQ 3

RQ 4

= Fulfilled = Not Fulfilled

🏆 Winner CSG-award: Group 5 - Litecoin - Decentralized eBay-like Marketplace (dBay)

Reports and Source Code

Please find the report and source code of each group for download at Source code is licensed under open source license. In case of questions, please contact the respective supervisor.