Posts tagged Utreexo
Utreexo: A dynamic hash-based accumulator optimized for the Bitcoin UTXO set

by Thaddeus Dryja (MIT’s Digital Currency Initiative)

AbstractIn the Bitcoin consensus network, all nodes come to agreement on the set of Unspent Transaction Outputs (The “UTXO” set). The size of this shared state is a scalability constraint for the network, as the size of the set expands as more users join the system, increasing resource requirements of all nodes. Decoupling the network’s state size from the storage requirements of individual machines would reduce hardware requirements of validating nodes. We introduce a hash based accumulator to locally represent the UTXO set, which is logarithmic in the size of the full set. Nodes attach and propagate inclusion proofs to the inputs of transactions, which along with the accumulator state, give all the information needed to validate a transaction. While the size of the inclusion proofs results in an increase in network traffic, these proofs can be discarded after verification, and aggregation methods can reduce their size to a manageable level of overhead. In our simulations of downloading Bitcoin’s blockchain up to early 2019 with 500MB of RAM allocated for caching, the proofs only add approximately 25% to the amount otherwise downloaded.

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Coindesk's 'This Scaling Tech Could Let You Sync Bitcoin Straight From Your Phone' using UTreeXO created by Tadge Dryja

“Maybe we don’t have to store everything ourselves.”

That’s Tadge Dryja, cryptocurrency research scientist at the MIT Digital Currency Initiative, explaining the concept behind his bitcoin scaling solution, “utreexo.”

Based on an idea that has been pursued by developers for many years, utreexo seeks to streamline an aspect of bitcoin’s code that leads to heavy storage requirements over time.

Read the original article here

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Utreexo: A dynamic accumulator for Bitcoin state - A description of research by Thaddeus Dryja

One of the earliest-seen and most persistent problems with Bitcoin has been scalability.  Bitcoin takes the idea of "be your own bank" quite literally, with every computer on the bitcoin network storing every account of every user who owns money in the system.  In Bitcoin, this is stored as a collection of "Unspent transaction outputs", or "utxo"s, which are somewhat unintuitive, but provide privacy and efficiency benefits over the alternative "account" based model used in traditional finance.

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