Decentralised consensus is a tough nut to crack
There’s a lot going on in the world of decentralised networking and not just the daily rollercoaster ride of the cryptocurrency markets. A decade after the mysterious Satoshi Nakamoto first unleashed Bitcoin on an unsuspecting world, the blockchain has grown and branched out and now a thousand flowers blossom, some of them rather peculiar blooms indeed.
Look around and you’ll see that blockchains are apparently the answer to every problem. From replacing the global banking system to guaranteeing the provenance of diamonds to paying your dentist – there’s a blockchain for that.
Overhyped they may be, but blockchains actually are a big deal and they will get bigger. Their potential for secure ‘trustless’ interchange is too great to ignore and once the silliness has died down inevitably some serious use cases will emerge.
Indeed that’s already starting to happen, hence this blog. We’ll be updating this page every few days to reflect the serious innovations bubbling up in this most interesting and volatile of spaces. (Also check out our rolling 5G coverage.)
But blockchains are not the only game in town. In fact, we kick off this blog with an announcement from a UK-based project that actually predates the blockchain, MaidSafe’s SAFE Network.
25/5/18 Ayr-based MaidSafe (the inspiration, incidentally, for the ‘new Internet’ Pied Piper in the HBO series Silicon Valley) has come up with what it claims is the most efficient solution yet to the well-known Byzantine Generals problem: achieving consensus across a masterless distributed network in which no one node can be seen as the ultimate source of truth. It’s a system the firm says could replace blockchain consensus for trustless data storage.
MaidSafe has been working on its peer-to-peer autonomous data network for more than a decade. Unlike traditional client-server networks, the SAFE Network has no central point of control. Instead, it is made up of users’ own machines which are used to randomly store encrypted chunks of the files uploaded to the network – a little like BitTorrent but without any central trackers and with everything encrypted. The idea is that it allows data storage (and eventually compute) with no single point of failure and in such a way that only the user has total control of his or her data. Only the user can grant access to people and applications that might want to share it. It also has its own integral cryptocurrency which is used to balance the give and take on the network.
Byzantine fault tolerance is a central issue for all decentralised distributed networks. In brief, how without a central point of authority can ‘truth’ be agreed upon? A particular node might be faulty or malicious but while another node nearby will see it as such a third node located in a far-flung part of the network might see it as perfectly fine because of the time taken for messages to traverse the infrastructure. Another way of looking at it is how can the network as a whole be sure of the order in which events happen on it?
This long-standing issue was finally solved by Bitcoin inventor Satoshi Nakamoto via the proof-of-work (PoW) consensus mechanism. Miners compete to be the first to solve a complex mathematical problem for which they are awarded Bitcoin and their particular version of the truth is put forward. The other nodes then come together to accept or reject this version and ultimately the network converges on the one true agreed state that will be used going forward. A key application is to prevent the problem of double-spend, where one might otherwise spend a Bitcoin simultaneously in two places.
But while Bitcoin has been highly successful in this regard the limitations of the blockchain regarding carrying capacity, scalability and throughput have become apparent. Moreover, the energy-intensive PoW consensus system has led to a high degree of centralisation since only large-scale professional miners with access to the latest ASICs and cheap electricity can now realistically earn Bitcoin in this way.
These issues make blockchains ill-suited as the basis for a data network – the equivalent of the internet or, looking further afield, the sort of heterogeous distributed networks represented by the IoT, the company says.
“The very design of blockchains means that their use case isn’t suited to a global internet that deals with vast amounts of data that needs to be both private and secure,” MaidSafe writes in a blog post.
The SAFE Network actually predates the Bitcoin blockchain by a couple of years but it is still at pre-release alpha stage. One of the key things that have held back progress is the difficulty in achieving a reliable consensus mechanism – the equivalent of PoW. However, this is a nut MaidSafe now claims to have cracked with PARSEC (Protocol for Asynchronous, Reliable, Secure and Efficient Consensus), a new algorithm based on a gossip protocol which the firm will open source under the GPL3 licence.
“It provides network consensus through maths and not through burning huge amounts of electricity,” said CEO David Irvine (pictured).
The blog goes into more detail: “The concept of Byzantine fault tolerance is a crucial one. It means that it is mathematically guaranteed that all parts of the network will come to the same agreement at a certain point in time. Exactly what PARSEC achieves.”
It continues: “With PARSEC, consensus is mathematically guaranteed as certain (as well as having a throughput that dwarfs blockchain tech). What’s more, PARSEC is highly asynchronous. This means that there is no trusted setup nor any synchronous steps involved.”
The company claims that PARSEC, a type of directed acyclic graph (DAG), offers significant advantages over other alternatives to PoW such as Proof of Stake. The nearest competitor would seem to be the Hashgraph DAG, but that has shortcomings when it comes to autonomous data network applications for the IoT, the firm says.
Got any breaking decentralised developments to tell us about? Let us know. (Mature projects with code published on GitHub or similar or a paper reproduced in an established journal please, rather than speculative stuff or coin news.)