🌳 Merkle Tree in Rust

This project implements a Merkle Tree in Rust using SHA-256 hashing (via the sha2 crate`.
It supports:

• Building a Merkle tree from a list of input values
• Automatic leaf duplication for odd counts
• SHA-256 hashing for leaves and parent nodes
• Recursive Merkle tree construction
• ASCII tree visualization

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🧠 What is a Merkle Tree?

A Merkle Tree is a binary tree where:

• Every leaf node contains the hash of some input data.
• Each internal node contains the hash of the concatenation of its two child nodes.
• The root hash cryptographically represents the entire dataset.

Merkle Trees are widely used in:

• Blockchain systems
• Distributed databases
• File integrity verification
• Peer-to-peer networks

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📦 Features

✔ Build a Merkle Tree Automatically

Pass a Vec<T> and the tree takes care of hashing, balancing, and node creation.

✔ SHA-256 Hashing

All leaf and parent nodes use the hash algorithm provided by the sha2 crate.

✔ Automatic Balancing

If the number of leaves is odd, the last leaf is duplicated to maintain a complete binary structure.

✔ Tree Visualization

The ASCII printing function produces output like this:

└── 3af...91bc
├── 19c...a23f
│   ├── 98f...1ac3
│   └── 11b...98dd
└── 4b9...de20
├── 77c...8120
└── 6ea...9f11

Clean and easy to understand.

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🚀 Usage

1. Input data

let mut data = vec![
    "a".to_owned(),
    "b".to_owned(),
    "c".to_owned(),
    "d".to_owned(),
    "e".to_owned(),
    "f".to_owned(),
    "g".to_owned(),
    "h".to_owned(),
];

2. Build the Merkle tree

let mut merkle_tree = MerkleTree::new();
merkle_tree.create(&mut data);

3. Print the tree

print_tree(Some(merkle_tree.root));

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📁 Project Structure

├── src
│   ├── main.rs
│
├── Cargo.toml
└── README.md

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🔧 Dependencies

Add this to your Cargo.toml:

[dependencies]
sha2 = "0.10"

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🧩 Main Components

MerkelNode

Represents a node in the tree:

struct MerkelNode {
    data: String,
    left: Option<Box<MerkelNode>>,
    right: Option<Box<MerkelNode>>,
}

MerkleTree

Handles constructing the entire tree and storing the root.

sha512_hash()

Utility function that computes a SHA-256 hash of any input convertible to bytes.

print_tree()

Pretty-prints the tree using ASCII symbols (├──, └──, │).

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▶ Running the Program

cargo run

You will see:

• The computed Merkle root
• The full tree printed in readable ASCII form

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🎯 Possible Improvements

• Merkle proof generation & verification
• JSON or binary serialization
• Colorized tree output
• Parallel hashing for performance
• Avoid unnecessary cloning of nodes

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📝 License

This project is open-source and free to use.