https://github.com/kevincharm/smt_fe

https://github.com/kevincharm/smt_fe

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• Host: GitHub
• URL: https://github.com/kevincharm/smt_fe
• Owner: kevincharm
• Created: 2023-11-18T11:29:04.000Z (12 months ago)
• Default Branch: master
• Last Pushed: 2023-11-18T12:13:33.000Z (12 months ago)
• Last Synced: 2024-04-14T13:46:01.820Z (7 months ago)
• Size: 1.95 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Efficient Sparse Merkle Tree Library for Fe

An optimised implementation of a Sparse Merkle Tree written in Fe that omits empty subtrees when computing roots. Empty subtrees are assumed to have a special hash value of zero. See [post on ethresear.ch](https://ethresear.ch/t/optimizing-sparse-merkle-trees/3751) for the original idea proposed by Vitalik.

## How to generate insert & update proofs

Below is an example JavaScript snippet that instantiates an SMT and generates proofs that can be used with this Fe lib.

```sh

npm install --save @kevincharm/sparse-merkle-tree @noble/hashes

```

```ts

import { SparseMerkleTreeKV } from "@kevincharm/sparse-merkle-tree";

import { ZeroHash, concat, hashMessage, Wallet, Contract } from "ethers";

// Initialise client representation of an empty SMT with depth=160

const smt = new SparseMerkleTree(160);

// Insert a new (K,V) entry

const index = BigInt(Wallet.createRandom().address);

const value = hashMessage("Fred Fredburger");

// Get SMT proof of insertion

const {

    newLeaf,

    leaf: oldLeaf

    index,

    enables,

    siblings,

} = smt.insert(index, value);

```

Then once we have these values, we can compute some roots:

```fe

use smt_fe::compute_address_smt_root

contract Main {

    root: u256

    pub fn main(

        mut self,

        newLeaf: u256,

        oldLeaf: u256,

        index: address,

        enables: u256,

        siblings: Array

    ) {

        let current_root: u256 = compute_address_smt_root(

            leaf: oldLeaf,

            index,

            enables,

            siblings

        )

        assert self.root = current_root

        let new_root: u256 = compute_address_smt_root(

            leaf: newLeaf,

            index,

            enables,

            siblings

        )

        self.root = new_root

    }

}

```