Paper 2018/968

Edrax: A Cryptocurrency with Stateless Transaction Validation

Alexander Chepurnoy, Charalampos Papamanthou, Shravan Srinivasan, and Yupeng Zhang

Abstract

We present EDRAX, an architecture for cryptocurrencies with stateless transaction validation. In EDRAX, miners and validating nodes process transactions and blocks simply by accessing a short commitment of the current state found in the most recent block. Therefore there is no need to store off-chain and on-disk, order-of-gigabytes large validation state. We present two instantiations of EDRAX, one in the UTXO model and one in the accounts model. Our UTXO instantiation uses sparse Merkle trees, which are very fast and require no trusted setup. Our accounts instantiation uses a distributed vector commitment, a type of vector commitment that has state-independent updates, meaning it can be synchronized by accessing only update data (e.g., send 5 ETH from Alice to Bob). Towards this goal, we build a new succinct distributed vector commitment based on multiplexer polynomials and zk-SNARKs, that scales up to one billion accounts. We perform an extensive experimental evaluation comparing to other (recently) proposed approaches for stateless transaction validation, showing that sparse Merkle trees and our new distributed vector commitment offer excellent tradeoffs in this application domain.