zkAttestor

Scalable on-chain trustless attestations to data from any past Ethereum block or state.

Project overview

This repository provides implementations of account, storage, and transaction proofs for Ethereum. Together, these enable a user to generate validity proofs for data from any current or past Ethereum block or state using a trusted block hash alone.

These implementations are for demonstration purposes only. These circuits are not audited, and this is not intended to be used as a library for production-grade applications.

Install dependencies

• Run yarn at the top level to install npm dependencies (snarkjs and circomlib).
• You'll also need circom version >= 2.0.2 on your system. Installation instructions here.
• To work with large circuits, follow the setup instructions at Best Practices for Large Circuits.
• Install Python libraries: eth-mpt, pysha3, rlp
• Building these circuits requires a Powers of Tau file with 2^24 constraints in the circuits subdirectory with the name pot24_final.ptau. One such file can be downloaded from the Hermez trusted setup here.

Building proving keys and witness generation files

We provide three circuits, which enable attestations to all current or historical Ethereum data available from an archive node with the exception of receipts, which are WIP:

• eth_block_hash: Prove state, transaction, and receipt roots corresponding to a block hash.
• eth_addr_storage: Prove the contents of a storage slot for an account from a block hash.
• eth_tx_proof: Prove the contents of a transaction from a block hash.

Run yarn build:eth_block_hash, yarn build:eth_addr_storage, yarn build:eth_tx_proof at the top level to compile proving keys and witness generators for each file.

These circuits are fairly large and require special hardware and setup to run: see Best Practices for Large Circuits.

Benchmarks

All benchmarks were run on a 32-core 3.1GHz, 256G RAM machine with 400G swap.

	EthBlockHash	EthAddressStorageProof	EthTransactionProof (< 7.5 kB)
Constraints	860K	13M	16.5M
Proving key size	418M	6.4G	7.8G
Witness generation	1s	14s	6s
Proving time	3s	25s	12s
Proof verification time	1s	1s	1s

Testing

Run yarn test at the top level to run tests. Tests are minimal at present and only test correctness of witness generation.

Acknowledgements

We use a circom implementation of keccak from Vocdoni as well as the eth-mpt Python library by popzxc and the Ethereum pyrlp library.