https://github.com/gregors/merkle_fun

Merkle Trees in Elixir
https://github.com/gregors/merkle_fun

merkle-proof merkle-root merkle-tree merkletree

Last synced: about 2 months ago
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Merkle Trees in Elixir

• Host: GitHub
• URL: https://github.com/gregors/merkle_fun
• Owner: gregors
• License: mit
• Created: 2022-04-08T20:27:25.000Z (over 2 years ago)
• Default Branch: main
• Last Pushed: 2022-10-24T18:50:18.000Z (about 2 years ago)
• Last Synced: 2024-05-29T22:31:22.270Z (7 months ago)
• Topics: merkle-proof, merkle-root, merkle-tree, merkletree
• Language: Elixir
• Homepage:
• Size: 92.8 KB
• Stars: 5
• Watchers: 2
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# MerkleFun

[Merkle tree](https://en.wikipedia.org/wiki/Merkle_tree) implementation using the excellent and fast rust-powered ex_keccak library under the hood.

If you'd like to know more about the basic algorithm, check out this great [introductory talk](https://youtu.be/HdGpG0kcEGU?t=132).

[![CircleCI](https://circleci.com/gh/gregors/merkle_fun/tree/main.svg?style=svg)](https://circleci.com/gh/gregors/merkle_fun/tree/main)

## Installation

The package can be installed

by adding `merkle_fun` to your list of dependencies in `mix.exs`:

```elixir

def deps do

  [

    {:merkle_fun, "~> 0.6.0"}

  ]

end

```

## Design

### binary tree

There are multiple ways to implement a binary tree. We decided to use an [array format](https://opendsa-server.cs.vt.edu/ODSA/Books/Everything/html/CompleteTree.html) approach to minimize storage requirements and make the sibling lookup easy. If it's been a while since you've done a basic data structures course, check out this [refresher](https://www.youtube.com/watch?v=zDlTxrEwxvg).

Wait a minute you say! Elixir doesn't have arrays? Well there is an [Erlang implementation](https://www.erlang.org/doc/man/array.html) as well as a nice [Elixir library](https://github.com/Qqwy/elixir-arrays). However, after thinking about the problem our use case didn't need updates. We build the tree and don't need to append further nodes. In such a case a tuple suits our [read only needs](https://stackoverflow.com/questions/16447921/arrays-implementation-in-erlang/16464349#16464349) perfectly. If we decide to add Merkle Mountain Ranges (in the future) we will need something with better append performance.

### leaf lookup

Initial leaf lookup is currently looking through the entire tree. Yeah I need to fix that.

## Warning

* second pre-image attack

* unbalanced trees attack

## Todo's

* [x] Make tree

* [x] Make proof

* [x] Validate proof

* [ ] Pretty Print tree

* [ ] Fast leaf look up

## Thanks

Thanks goes out to Rodger Maarfi (@acrite22) for pairing with me on this.

Documentation can be generated with [ExDoc](https://github.com/elixir-lang/ex_doc)

and published on [HexDocs](https://hexdocs.pm). Once published, the docs can

be found at .