Cryptology ePrint Archive: Report 2021/1361

Plumo: An Ultralight Blockchain Client

Psi Vesely and Kobi Gurkan and Michael Straka and Ariel Gabizon and Philipp Jovanovic and Georgios Konstantopoulos and Asa Oines and Marek Olszewski and and Eran Tromer

Abstract: Syncing the latest state of a blockchain can be a resource-intensive task, driving (especially mobile) end users towards centralized services offering instant access. To expand full decentralized access to anyone with a mobile phone, we introduce a consensus-agnostic compiler for constructing {\em ultralight clients}, providing secure and highly efficient blockchain syncing via a sequence of SNARK-based state transition proofs, and prove its security formally. Instantiating this, we present Plumo, an ultralight client for the Celo blockchain capable of syncing the latest network state summary in just a few seconds even on a low-end mobile phone. In Plumo, each transition proof covers four months of blockchain history and can be produced for just $25 USD of compute. Plumo achieves this level of efficiency thanks to two new SNARK-friendly constructions, which may also be of independent interest: a new BLS-based offline aggregate multisignature scheme in which signers do not have to know the members of their multisignature group in advance, and a new composite algebraic-symmetric cryptographic hash function.

Category / Keywords: applications / Ultralight clients, SNARKs, aggregate multisignatures

Date: received 10 Oct 2021, last revised 13 Oct 2021

Contact author: psi at ucsd edu, mstraka at clabs co

Available format(s): PDF | BibTeX Citation

Version: 20211013:204257 (All versions of this report)

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