Block roots archive

The Block Roots Archive is a caching layer including a data scraper and a server designed to aggregate and provide access to all the block roots within a single Sync Committee period of the Beacon API of Ethereum. This system features a scraper responsible for continually updating an SQLite database with new block roots and retroactively filling in data for past blocks. Additionally, it includes an API that offers a endpoint to retrieve block roots for any given period.

Motivation: Generating Ancestry proofs

As outlined here, within Ethereum's consensus layer, there are primarily two ways to prove that a block is a predecessor of another one. The initial approach leverages the block_roots property of the beacon state, encapsulating the roots of blocks from the most recent period (approximately 27 hours). For blocks extending beyond this timeframe, the historical_summaries beacon state attribute comes into play.

More precisely, the block_roots attribute is a vector that holds the roots of blocks within the current historical root timeframe. This vector is fixed in size, equivalent to the SLOTS_PER_HISTORICAL_ROOT ETH constant, which is presently 8192. Upon reaching its capacity, the vector undergoes Merkleization, and its root is then preserved within the `historical_summaries`` vector.

In scenarios where the Beacon root that we want to generate the ancestry proof for is recent enough, a Merkle inclusion proof suffices. But in the latter case where the block is older than 8192 blocks (~27 hours), the Merkle tree of the `block_roots`` of that specific period must be reconstructed. Given the absence of a mechanism to batch request 8192 block roots in the Beacon API, this implementation scrapes and serves the block_roots for sync-committee periods in a single request.

Setup

• Copy .env.template to .env and populate it accordingly
• Run yarn to install necessary dependencies.

Scraping

During the first time that the scraper will start, it will initialize the database automatically. Currently, there are 2 supported methods

• Backfilling: Starting from the startSlot stated in the .env file, the scraper will start backfilling the block roots till it fails or reaches block 0. This is enabled by setting the BACKFILL_MODE to true on the .env file.
• Syncing: Starting from the startSlot stated in the .env file, the scraper will start scraping block roots indefinitely to always stay in sync with the newly minted block roots. This is the default mode if nothing is set to the .env file.

To start the scraper, just run yarn scrape.

Serving

Considering that the SQLite database is populated with the periods that we are interested in, running yarn serve will expose a single endpoint:

Block Summary

This endpoint returns a vector of SLOTS_PER_HISTORICAL_ROOT (8192) block roots. The request must specify the sync committee period.

GET /block_summary?period=12

Example responses

  {
    "code":200,
    "data":["0xe4f5947b48bc7bc4cdde1013f3f28ba681633cd4d75a5b7e395b348e38111704", ".", ".", "." ]
  }

  {
    "code":404,
    "message":"Block roots tree not found for period: 23432"
  }