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Technical Diff Overview

Many modifications were made to successfully support fraud proofs and secure batch posting. The following is an in-depth summary which describes the key changes made to the core Arbitrum stack to enable secure compatibility with EigenDA.

Batch Submission & Derivation​

Nitro​

  • Extended batch poster to take in an eigenDAWriter struct that writes blobs to DA via eigenda-proxy
    • Embed ABI calldata for tx submissions to SequencerInbox
  • Extended inbox message derivation to support type processing for an eigenda batch type (i.e, 0xed prefix)
  • Compute batchHeaderHash locally using batchHeader fields when querying blobs from eigenda proxy
  • Updated batch poster config to support 16Mib batches when using eigenda
  • Increased maxDecompressedLen batch encoding limit to support 40mib batches post-compression

Nitro Contracts​

  • Extended SequencerInbox.sol to support new entry-point function for processing eigenda batch types (i.e, addSequencerL2BatchFromEigenDA)
    • Verifies certificates against stateful dependency RollupManager.sol contract which handles communication with EigenDAServiceManager.sol
    • Updated data hash computation where hash = keccak256(msgHeader, bytePrefixFlag, abi.Pack(commitment.X, commitment.Y, blob.len()))
  • Updated forge tests to verify inbox submission flow
  • Updated deployment scripts to deploy a contract adhering to the RollupManager interface which lives as part of the RollupDeployer contract parameters and is set to the SequencerInbox storage after deployment. Currently the only supported contracts with this interface are the L1BlobVerifier and L2BlobVerifier contracts which perform alternative verifications based on the parent chain depth.

Nitro TestNode​

  • Updated config.ts to enable eigenda system flow
  • Updated docker-compose.yml to use eigenda-proxy dependency with
  • Updated core bash script to deploy and teardown eigenda-proxy resource
  • Added a monitoring flag to bash script to allow for spinning up observability (i.e, grafana, loki log aggregation)
  • Added a flood script to support traffic generation for specific data throughput rates (e.g, kb/s) against a testnode sequencer

Nitro Go-Ethereum​

  • Updated system configs to use eigenda field

Fraud Proofs & Stateless Block Execution​

Nitro​

  • Default encode blobs (i.e, modulo encode, length prefix encoding, pad to nearest of 2) before pre-image injection to ensure data is in proper format for generating kzg commitments and witness proofs
  • Decode blobs to raw binary or nitro compressed batch representation when reading
  • Generate pre-image hashes using the length and commitment fields provided by the eigenda certificate which is persisted into the sequencer inbox

Arbitrator

  • Extended arbitrator to use an eigenda preimage type which is targeted during transpilation from host go code (i.e, WavmReadEigenDAHashPreimage)
  • Embed mainnet SRS values into test-files subdirectory (i.e, g1.point, g2.point, g2.point.powerOf2)
  • Updated machine proof serialization logic to target prove_kzg_preimage_bn254 when preimage.type() == PreimageType::EigenDAHash
  • Add custom proof generation logic for READPREIMAGE opcode with EigenDAHash type which computes a machine state proof containing a kzg proof using a point opening at the 32 byte offset.
  • Extended E2E proof equivalence tests to serialize machine state proofs using EigenDA preimage types and ensure that post-states when one step proven on-chain match the post-state machine hashes generated by the off-chain arbitrator opcode test
  • Built kzg-bn254 library for performing kzg operations over the bn254 curve in rust

Validator

Updated replay script (replay/main.go) to use eigenDAReader when populating pre-image oracle for stateless block execution. EigenDA preimage type hashes are computed as:

keccak256(commitment.X, commitment.Y, preimage.len())

Computing the length as part of the preimage hash is necessary for removing a trust assumption on a bridge validator. Unlike 4844, EigenDA preimages are variadic in size.

Nitro Contracts​

  • Extended OneStepProverHostIO.sol to perform bn254 kzg pairing verifications for an opening proof provided by a challenger
  • Added forge tests to assert the correctness of proof verification logic