One of the minds behind the Lightning Network — Bitcoin’s proposed second-layer scaling solution — has just authored a paper formally outlining another method for optimizing the reigning public blockchain.
That mind, Tadge Dryja, is a researcher at the Massachusetts Institute of Technology’s Digital Currency Initiative. He’s renowned in the cryptoverse for having co-published the Lightning whitepaper with Joseph Poon in 2016.
His newest contribution to the cryptocurrency scaling arena? Utreexo, a so-called accumulator, which would slim down unspent transaction output (UTXO) sets, or the state, for Bitcoin full nodes. The result of the slimming would be making such full nodes easier and less costly to run, i.e. slowing the usage of storage space.
I've posted Utreexo, a new paper about bitcoin scalability, to IACR ePrint. https://t.co/3byL1Xekj6
Thanks to those who helped with this work and looking forward to criticisms and getting and implementation running.
— Tadge Dryja (@tdryja) June 3, 2019
To that end, Utreexo can be used to streamline validating in Bitcoin. As Dryja explained of the system:
“In this paper we present Utreexo, a method for greatly reducing the storage needed to run a fully validating node. In hardware setups where disk I/O speeds and storage requirements are the bottleneck, this can significantly accelerate the validation process, or make validation possible on hardware where it previously has not been.”
Indeed, Utreexo and methods like it could pave the way to users eventually running Bitcoin full nodes straight from their smartphones.
The idea for accumulators have been around for more than two decades, and Dryja’s Utreexo isn’t the only accumulator work that’s been pursued in the cryptocurrency ecosystem to date — for example, leading researchers at the Computer Science Department at Stanford University have had their own relevant ideas.
Yet Dryja’s Utreexo whitepaper suggests the long sought tech is closer to reality than ever, and his methodology is likely to usher in a new wave of accumulator research in the space. And that means full nodes may imminently be getting lighter and lighter.
As Benedikt Bünz, one of those aforementioned Stanford researchers, has previously commented on accumulator-focused innovation:
“The high level is this idea of separating the consensus away from the state. Anyone can now be a full node without having to store the data.”
Now that Utreexo is open for review, it may only be a matter of time until a wallet project first implements the tech.
Another Bitcoin Scaling Angle to Consider? Statechains
For some, the Lightning Network and block size increases are the predominant possible avenues for scaling Bitcoin. But they aren’t the only avenues. Alternative and contribution solutions, like Utreexo, are rising.
Another one of these alternative solutions? Statechains, a new and trusted scaling protocol.
1/4 #Statechains are a novel layer two protocol, designed for off-chain Bitcoin transfer. It is facilitated by a multisig federation which never has complete control, making it non-custodial. Check out my new article, or keep reading below for a summary!👇https://t.co/kDRA2QhVkk
— Ruben Somsen ⚡️🇳🅾️2️⃣❎ (@SomsenRuben) June 4, 2019
Authored by Seoul Bitcoin Meetup founder Ruben Somsen, statechains are not a competing solution to Lightning but could rather work in parallel as coordinated off-chain systems. As Somsen explained in a recent introductory post on the tech:
“The basic idea behind Statechains is that you lock up money between two parties in a 2-of-2 multisig: the Statechain entity and the user. When the user wants to transfer the money (the entire UTXO), they simply hand over their private key, which we call the transitory key, to the intended recipient.”
Somsen went on to add that, “in a nutshell this is the core concept, and […] it’s deceptively powerful.”
Scaling Will Need Privacy, BOLT May Be the Ticket
As the Lightning Network’s progress continues to hum along, Bolt Labs is angling to boost the second-layer scaling solution’s privacy.
The startup raised $1.5 million USD in April to further its mission of using the BOLT Protocol to bring anonymous shielded addresses to users of Lightning, ZCash, and beyond.
Bolt Labs’s founder Dr. Ayo Akinyele has said BOLT can make it so “no one can link you to [a] payment unless you disclose the information.” Thus with the march of innovations like BOLT, Utreexo, and statechains, second-layer infrastructure is steadily blooming in multiple directions.