da-light-client

Light client for Data Availability Blockchain of Polygon 🐿

OnChain DA LightClient's primary version available here

Introduction

Naive approach for building one DA light client, which will do following

• Listen for newly mined blocks
• As soon as new block is available, attempts to eventually gain confidence by asking for proof from full client ( via JSON RPC interface ) for N many cells where cell is defined as {row, col} pair
• For lower numbered blocks, for which no confidence is yet gained, does batch processing in reverse order i.e. prioritizing latest blocks over older ones

Installation

• First clone this repo in your local setup & run 👇 in root of this project, which will download all dependencies

npm i

• Create one .env file in root of project & put following content

touch .env

WSURI=ws://localhost:9944
AskProofCount=15
BatchSize=10
PORT=7000

Environment Variable	Interpretation
WSURI	Light client subcribes to full node, over Websocket transport, for receiving notification, as soon as new block gets mined
AskProofCount	For each new block seen by light client, it'll ask for these many proofs & verify those
BatchSize	At max this many blocks to be attempted to be verified, asynchronously, in a single go
PORT	Light client exposes RPC server over HTTP, at this port number

• Now, let's run light client

make run

Usage

Given block number ( as (hexa-) decimal number ) returns confidence obtained by light client for this block

curl -s localhost:7000/v1/confidence | jq

{
    "number": 223,
    "confidence": 99.90234375,
    "serialisedConfidence": "958776730446"
}

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Note : Serialised confidence has been added recently so that it can be consumed by smart contract light client. This field is computed as below

blockNumber << 32 | int32(confidence * 10 ** 7), where confidence is represented as out of 10 ** 9