Project Overview

Project Overview

Minichain is a single-node, account-based blockchain with a register-based virtual machine, Proof of Authority consensus, and persistent storage.

Design Philosophy

We prioritize learning over production-readiness. Every component is designed to be:

• Understandable — Clear, well-documented code
• Minimal — No unnecessary features
• Complete — A working end-to-end system

Architecture

┌─────────────┐
│     CLI     │ ← User interface
└──────┬──────┘
       │
┌──────┴──────┐
│    Chain    │ ← Orchestration
└──────┬──────┘
       │
┌──────┴──────┬───────────┬───────────┐
│     VM      │ Consensus │  Storage  │
└──────┬──────┴─────┬─────┴─────┬─────┘
       │            │           │
       └────────────┴───────────┘
                    │
              ┌─────┴─────┐
              │   Core    │ ← Primitives
              └───────────┘

Crate Dependencies

Crate	Depends On	Purpose
core	—	Primitives: hashing, crypto, blocks, transactions
vm	core	Virtual machine execution
storage	core	Persistent state with sled
consensus	core	PoA validation
chain	core, vm, storage, consensus	Blockchain logic
assembler	core	Assembly → bytecode
cli	all	User interface

Key Technologies

Component	Technology	Why
Hashing	Blake3	Fast, secure, modern (blake3 crate)
Signing	Ed25519	Fast, compact signatures (ed25519-dalek crate, comparison)
Storage	sled	Embedded, transactional
Serialization	bincode	Compact binary format
CLI	clap	Rust standard for CLIs

Featured Smart Contract

The project includes a complete English Auction smart contract walkthrough, including storage layout, dispatch flow, CLI usage, and integration tests.

• English Auction Smart Contract

Account Model

We use an account-based model (like Ethereum) rather than UTXO (like Bitcoin):

pub struct Account {
    pub nonce: u64,           // Transaction count
    pub balance: u64,         // Balance in MIC (Mini Coin)
    pub code_hash: Option<Hash>,  // Contract bytecode hash
    pub storage_root: Hash,   // Storage trie root
}

Why account-based?

• Simpler mental model
• Easier smart contract state
• Natural fit for our VM

Native Token: Mini Coin (MIC)

Minichain has a native cryptocurrency called Mini Coin with the symbol MIC. It serves multiple purposes:

• Transaction fees — MIC is used to pay for gas when executing transactions and deploying/calling contracts
• Account funding — Initial MIC is minted by authorities for testing purposes
• Value transfer — MIC can be sent between accounts as a native value

Token Details

Property	Value
Name	Mini Coin
Symbol	MIC
Decimals	0 (whole units only)
Initial Supply	0 (minted by authorities)

Getting MIC

For testing, authorities can mint MIC using the CLI:

minichain account mint --from authority_0 --to <ADDRESS> --amount 1000

MIC can also be received through transactions from other accounts.

Consensus: Proof of Authority

For simplicity, we use Proof of Authority (PoA):

• Single trusted authority signs blocks
• No mining or staking complexity
• Instant finality
• Perfect for learning and private chains

What’s Next?

Let’s start building! Head to Chapter 1: Core Primitives to implement the foundation.