TxChain: efficient cyptocurrency light clients via contingent transaction aggregation.
OA Location
Author(s)
Zamyatin, Alexei
Avarikioti, Zeta
Perez, Daniel
Knottenbelt, William J
Type
Working Paper
Abstract
Cryptocurrency light- or simplified payment verification (SPV) clients
allow nodes with limited resources to efficiently verify execution of payments.
Instead of downloading the entire blockchain, only block headers and selected
transactions are stored. Still, the storage and bandwidth cost, linear in blockchain
size, remain non-negligible, especially for smart contracts and mobile devices: as
of April 2020, these amount to 50 MB in Bitcoin and 5 GB in Ethereum.
Recently, two improved sublinear light clients were proposed: to validate the
blockchain, NIPoPoWs and FlyClient only download a polylogarithmic number
of block headers, sampled at random. The actual verification of payments, however, remains costly: for each verified transaction, the corresponding block must
too be downloaded. This yields NIPoPoWs and FlyClient only effective under
low transaction volumes.
We present TXCHAIN, a novel mechanism to maintain efficiency of light clients
even under high transaction volumes. Specifically, we introduce the concept of
contingent transaction aggregation, where proving inclusion of a single contingent transaction implicitly proves that n other transactions exist in the blockchain.
To verify n payments, TXCHAIN requires a only single transaction in the best
(n ≤ c), and d
n
c + logc(n)e transactions in the worst case (n > c). We deploy
TXCHAIN on Bitcoin without consensus changes and implement a soft fork for
Ethereum. To demonstrate effectiveness in the cross-chain setting, we implement
TXCHAIN as a smart contract on Ethereum to efficiently verify Bitcoin payments.
allow nodes with limited resources to efficiently verify execution of payments.
Instead of downloading the entire blockchain, only block headers and selected
transactions are stored. Still, the storage and bandwidth cost, linear in blockchain
size, remain non-negligible, especially for smart contracts and mobile devices: as
of April 2020, these amount to 50 MB in Bitcoin and 5 GB in Ethereum.
Recently, two improved sublinear light clients were proposed: to validate the
blockchain, NIPoPoWs and FlyClient only download a polylogarithmic number
of block headers, sampled at random. The actual verification of payments, however, remains costly: for each verified transaction, the corresponding block must
too be downloaded. This yields NIPoPoWs and FlyClient only effective under
low transaction volumes.
We present TXCHAIN, a novel mechanism to maintain efficiency of light clients
even under high transaction volumes. Specifically, we introduce the concept of
contingent transaction aggregation, where proving inclusion of a single contingent transaction implicitly proves that n other transactions exist in the blockchain.
To verify n payments, TXCHAIN requires a only single transaction in the best
(n ≤ c), and d
n
c + logc(n)e transactions in the worst case (n > c). We deploy
TXCHAIN on Bitcoin without consensus changes and implement a soft fork for
Ethereum. To demonstrate effectiveness in the cross-chain setting, we implement
TXCHAIN as a smart contract on Ethereum to efficiently verify Bitcoin payments.
Date Issued
2020
Citation
2020
Publisher
Cryptology ePrint Archive
Copyright Statement
© 2020 The Author(s)
Identifier
https://eprint.iacr.org/2020/580.pdf
Publication Status
Published