Where’s Greg? Maxwell Eyes New Bitcoin Projects After Blockstream

One of bitcoin’s most respected developers, Gregory Maxwell, is returning to his cypherpunk roots with a series of new projects.

After nearly four years as CTO of high-profile bitcoin technology startup Blockstream, he’s departed that position to focus exclusively on code. Mainly because, as Maxwell explained in his departure letter, he accomplished what he set out to do at the startup, addressing the “significant under-investment” in bitcoin’s technology at the time he joined.

But with a “much larger and more active” developer community around bitcoin today, Maxwell is going into 2018 an untethered man set on improving bitcoin smart contracts.

In this pursuit, Maxwell published a paper on something called “Taproot” in mid-January, an idea that improves upon the privacy of MAST, an idea, long in the making, that could beef up bitcoin’s smart contract abilities. Days later, Maxwell released another proposal called “Graftroot,” improving on MAST further.

So, why is this focus so attractive for Maxwell?

Maxwell told CoinDesk:

“I expect every transaction to eventually use these tools, at least in limited ways. They are an incremental improvement, making things that were already more or less possible more private and efficient. They replace or make much better things like MAST.”

And so far, many developers have praised Maxwell’s new work.

“Taproot is annoyingly clever,” Lightning Network creator Tadge Dryja quipped on Twitter, adding that while the idea sounds simple in hindsight, no one had thought about it before Maxwell.

Like a dandelion?

Maxwell’s interest seems to be aligning with greater attention to MAST now that SegWit (a code change MAST depends on) has been activated on bitcoin.

To understand MAST, it’s helpful to start by looking one of the common use cases of bitcoin today – M-and-N multi-signatures, which require that coins can only be spent if a certain number of users (such as two-of-two, three-of-five) approve the transaction. One problem that can arise in these types of transactions is that one party loses their private key to sign with or just decides altogether not to comply, and at that point the money is unspendable.

MAST allows users to add additional conditions for when a transaction can be spent in a more efficient way, helping to solve the above issue.

For example, a transaction can be set to lose the need for multiple signatures, if the multi-signature funds aren’t spent after, say, 10 years. The magic of MAST is that it can cram all of this logic into one transaction efficiently.

In short, with Taproot and Graftroot, Maxwell has found a way to further improve privacy for these advanced transactions.

In Maxwell’s eyes, the problem with MAST as it stands is that each MAST transaction looks different than a normal transaction, which can be harmful for privacy, since people viewing bitcoin’s public ledger could theoretically glean which transactions are using MAST and in turn, more about financial transactions they have no business knowing anything about.

Taproot improves privacy in MAST instances where multi-signatures is used, by making those transactions, once settled on the blockchain, look the same as other transactions…

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