LYRATA: Proof-of-Useful-Bandwidth Blockchain Against Persistent Adversaries
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2026-11-05
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Abstract
Permissionless blockchains are subject to sybil attacks. They typically rely on Proof-of-X (such as Proof-of-Work), for sybil defense. Here "X" is a resource which the adversary only has limited supply. While effective, such Proof-of-X systems often result in significant resource waste. To avoid such waste, thiswork explores sybil defense based on in-protocol bandwidth consumption. Here in-protocol bandwidth consumption refers to bandwidth that is already consumed by the blockchain for providing the basic functionality of a distributed ledger.
As our main contribution, this work proposes a novel blockchain LYRATA, with a simple yet elegant design. To our knowledge, LYRATA is the very first blockchain that can i) minimize resource waste by exploiting in-protocol bandwidth consumption, and ii) offer strong security guarantees under standard persistent adversaries. We have further implemented a research prototype of LYRATA. Our experimental results show that LYRATA also offers good practical end-to-end performance.