Games, Graphics and New Tech · Blockchain
Build a simple blockchain
Implement blocks, hashes, proof of work and validation to see how a chain resists tampering.
- DifficultyIntermediate
- Estimated time1–2 weeks
- Budget₹0
- ClassClass 12 to college
- TeamSolo or up to 2
- You needComputer only
Prerequisites: None beyond your class work
Original · by TechnifyedSimulationSoftware ProjectFree to doComputer onlyWell documented
Overview
Implement blocks, hashes, proof of work and validation to see how a chain resists tampering.
Why build this?
Twenty lines of code replace a lot of vague explanation about how a chain resists tampering.
What you will learn
- What a hash is
- How blocks are linked
- What proof of work costs
Skills you will use
Materials and tools
- Computer with Python 3
Tools and software
Step-by-step roadmap
Start
You will finish with: a working chain and a demonstration of tamper detection.
- 1
Prerequisites
Nothing special to know first. Then collect the 1 item in the materials list.
- 2
Learn
- What a hash is
- How blocks are linked
- What proof of work costs
- 3
Plan
List the features for version one, sketch the screens or data flow and pick the tools. Keep the first version small.
- 4
Build
- Define a block with data, a timestamp and the previous hash.
- Compute each block's hash.
- Add proof of work with adjustable difficulty.
- Write a function that validates the whole chain.
- Change an old block and show validation fails.
- 5
Test
Try it with wrong, empty and unusual input, and ask someone else to use it without your help.
- 6
Document
Write a README: what it does, how to run it, screenshots and what you learned. Report structure
- 7
Present
Show a live demo of one complete task, then the design and the hardest problem you solved. Presentation structure · Viva questions
- 8
Publish
Put the code on GitHub with the README and, if you can, deploy a live demo.
Expected outcome
A working chain and a demonstration of tamper detection.
Other versions of this project
Beginner version
Link three blocks by hash without proof of work.
Advanced version
Run two nodes that exchange blocks and resolve conflicts.
Make this project better
- BasicLink three blocks by hash without proof of work.
- This projectBuild a simple blockchain
- AdvancedRun two nodes that exchange blocks and resolve conflicts.
Ways to do this project
Text marked "You write this" is a prompt for your own work; everything else is specific to this project.
Use this as the outline of your README or case study.
- Problem
- You write thisThe problem in one or two sentences.
- Why it matters
- Twenty lines of code replace a lot of vague explanation about how a chain resists tampering.
- What was built
- A working chain and a demonstration of tamper detection.
- Technology
- Python
- Architecture
- You write thisOne diagram: the parts and how data moves between them.
- Implementation
- You write thisThe 5 build steps in your own words, with one code or design decision you are proud of.
- Challenges
- You write thisThe hardest bug or decision, and how you got past it.
- Results
- You write thisNumbers: accuracy, speed, users, survey answers.
- Demo and code
- You write thisA link to a live demo or a short video, and to the GitHub repository.
- Lessons learned
- You write thisWhat you would do differently next time.
- Future improvements
- Run two nodes that exchange blocks and resolve conflicts.
- Problem
- Implement blocks, hashes, proof of work and validation to see how a chain resists tampering.
- Target user
- You write thisOne specific person: who they are and when they would use this.
- Solution
- Implement blocks, hashes, proof of work and validation to see how a chain resists tampering.
- First version (MVP)
- Link three blocks by hash without proof of work.
- Tech stack
- Python
- Architecture
- You write thisA quick sketch of the parts and how they connect.
- Demo
- You write thisThe one scenario you will show live, start to finish, in under two minutes.
- Stretch goals
- Run two nodes that exchange blocks and resolve conflicts.
Team roles
Plan by length
24-hour
- Hours 0–2: agree the problem, the user and the one thing the demo must show
- Hours 2–16: build only the first version
- Hours 16–20: test the demo path end to end and fix what breaks
- Hours 20–24: slides, a 2-minute demo script and a backup recording
48-hour
- Evening 1: problem, user, sketch and task split
- Day 1: first version working end to end
- Day 2 morning: one stretch goal and testing
- Day 2 afternoon: polish, slides and demo practice
1-week
- Day 1: research the problem and talk to two possible users
- Days 2–4: first version
- Day 5: stretch goals
- Day 6: testing and write-up
- Day 7: demo video and presentation
Working as a team
Solo or up to 2. Suggested roles:
Report and presentation
Report structure
- Title and summary
- Problem and target user
- Features
- Tools and technology
- Design: architecture, data model or screens
- Implementation
- Testing
- Results and screenshots
- Challenges
- Future improvements
- References
Presentation structure
- The problem
- Who it is for
- Live demo
- How it is built (one diagram)
- The hardest part
- Testing and results
- What you learned
- What comes next
Viva questions
Try answering before you open each one.
What is a hash?
A fixed-length fingerprint of data that changes completely if the data changes.
Why does changing an old block break the chain?
Its hash changes, so the next block's stored previous hash no longer matches.
What is proof of work?
Making a block costly to create by requiring a hash with a set pattern.
Resources
CS50's Introduction to Programming with Python (CS50P) 2022Harvard University · Free video course
Python for Data ScienceIBM · Free course course
MIT 6.100L Introduction to CS and Programming using Python, Fall 2022Massachusetts Institute of Technology · Free video coursePython documentationdocs.python.orgSource and attribution
Original
Written by Technifyed. Free to use for your own school or college project; write the report in your own words. Added 1 Oct 2026.
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