🦀 Mini Blockchain (Rust) — Educational PoC

A step-by-step Proof-of-Concept to build a Bitcoin-style mini blockchain in Rust.
Learn core blockchain concepts: blocks, hashing, Proof of Work, transactions, mining rewards, and optional networking.

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🚀 Project Overview

This project is designed for educational purposes.
You'll build a simple blockchain from scratch, understand how Bitcoin works under the hood, and gradually add more features.

Core concepts covered:

• Block structure and linking
• SHA-256 hashing
• Proof of Work (mining)
• Transaction mempool
• Mining rewards
• Chain validation
• Optional REST API and node synchronization

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📍 Roadmap / Exercises

Exercise 1 — Create a Minimal Block

Goal: Understand the basic block structure.

Tasks:

• Create a Block struct with:
  • index: u32
  • timestamp: u64
  • transactions: Vec<Transaction> (can be a simple struct or string for now)
  • previous_hash: String
• Add a method to serialize the block into a string (for hashing later).

Success criteria:

• You can create a block and print its serialized form.

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Exercise 2 — Add SHA-256 Hashing

Goal: Understand cryptographic hashes.

Tasks:

• Add a method compute_hash(&self) -> String to compute SHA-256 on the block's serialized content.
• Ensure the hash changes if the block is modified.

Crates:

• sha2 for hashing
• serde + serde_json for serialization

Success criteria:

• Printing block.compute_hash() works.
• Changing block data changes the hash.

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Exercise 3 — Build the Blockchain

Goal: Link blocks into a chain.

Tasks:

• Create a Blockchain struct with chain: Vec<Block> and difficulty: usize.
• Create a genesis block (previous_hash = "0").
• Implement add_block() to create new blocks, set previous_hash, compute hash, and append to the chain.

Success criteria:

• You can create a chain with multiple linked blocks.

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Exercise 4 — Validate the Chain

Goal: Ensure blockchain integrity.

Tasks:

• Implement is_chain_valid() -> bool:
  • Verify each block’s hash matches its contents.
  • Verify previous_hash matches the previous block.
• Test by manually modifying a block.

Success criteria:

• Any tampering breaks validation.

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Exercise 5 — Add Proof of Work (Mining)

Goal: Implement mining similar to Bitcoin.

Tasks:

• Add nonce: u64 to Block.
• Implement mine(&mut self):
  • Increment nonce until the hash starts with difficulty zeros.

Success criteria:

• Mining changes the hash to meet the difficulty.

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Exercise 6 — Add Transactions

Goal: Simulate a mempool.

Tasks:

• Create a Transaction struct: from: String, to: String, amount: f32.
• Add pending_transactions: Vec<Transaction> in Blockchain.
• Implement add_transaction(tx: Transaction) and mine_pending_transactions():
  • Create a block with pending transactions.
  • Mine it and add to the chain.
  • Clear pending transactions.

Success criteria:

• Multiple transactions can be mined into a block.

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Exercise 7 — Add Mining Rewards

Goal: Mimic Bitcoin’s block reward.

Tasks:

• Automatically include a special transaction in mined blocks:
  • from = "network"
  • to = <miner_name>
  • amount = <reward>

Success criteria:

• Miner earns coins each time a block is mined.

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Exercise 8 — Optional: Minimal REST API

Goal: Turn blockchain into a node.

Tasks:

• Use warp or actix-web to expose endpoints:
  • GET /chain → returns full blockchain
  • POST /transaction/new → add new transaction
  • GET /mine → mine pending transactions

Success criteria:

• Interact with the blockchain via browser or HTTP client.

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Exercise 9 — Optional: Node Synchronization

Goal: Learn distributed consensus.

Tasks:

• Allow nodes to know each other.
• Implement “longest valid chain wins”:
  • Compare chains between nodes
  • Keep the longest valid chain

Success criteria:

• Nodes synchronize and resolve conflicts automatically.

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🔧 Next Steps / Advanced

• Implement a UTXO model
• Sign transactions with ECDSA (k256 crate)
• Add dynamic difficulty adjustment
• Build a peer-to-peer network (TCP/WebSocket)
• Limit block size and mempool rules

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⚡ Recommended Rust Crates

• sha2 — SHA-256 hashing
• serde + serde_json — Serialization / JSON handling
• chrono — Optional, for timestamps
• warp / actix-web — Optional, REST API
• k256 — Optional, for ECDSA signatures

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📝 License

MIT / Educational use