How MAST and Taproot Could Help in Maintaining Privacy on the Blockchain

Gregory Maxwell, one of the most widely known bitcoin developers, announced via a blog post that he is moving on to fulfill a new technological pet project of his called as Taproot. Taproot revolves around the idea of Merkelized Abstract Syntax Trees (MAST).

Updating Privacy Standards on the Bitcoin Blockchain

Taproot could enhance bitcoin’s smart contract abilities. Speaking to a renowned blockchain news portal about this, Maxwell said:

“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.”

After leaving the bitcoin technology startup Blockstream, he published a paper on January 23, 2018, describing the technology.

When a transaction takes place on the blockchain, the sender needs to use his private key to validate the transaction. This process is relatively simple if in a given transaction there is only one sender. However, when there are multiple senders, then they can create a two of two or three of five groups of users to validate the transaction.

Greg Maxwell has been busy thinking about how to leverage MAST for further privacy improvements. "Taproot" is a concept that enables devs to write efficient complex smart contracts that third party observers would only think are simple payments. https://t.co/G82NXXmSIF pic.twitter.com/flkOqZTfUO

— Jameson Lopp (@lopp) January 23, 2018

This grouping is known as M-and-N multi signatures, which means that the digital coins will be released only after it has been approved by a minimum of those fixed number of users. A significant problem in such transactions is that if any of those senders lose their private key or purposely do not validate the operation, the whole transaction is delayed until it does get approved.

MAST also allows users to add conditions to a smart contract to prevent such a scenario from happening. For instance, if a condition needs to be added in the case of funds with multiple signatures not being spent after ten years, MAST can cram all this logic into one single transaction.

Two users can create a resolution of their contract and jointly form a two of two signature and spend as if they were a single entity.

The Taproot consensus rules would then allow anyone who would provide the network with an original combined pubkey and pass the criteria for getting the transaction verified and signed.

Old Hands, New Developments

The concept is not something new for Maxwell. On October 13, 2013, he created a thread on bitcointalk describing how he would create a protocol that would make anonymous transactions simpler for those who do not wish to disclose their details. Taproot and Graftroot are both new ways that could help in improving the privacy of these transactions.

A problem with MAST transactions is that they look distinctly different from other transactions on the blockchain. People viewing the ledger would immediately come to know which accounts are associated with MAST transactions. Taproot is an excellent solution to this in that it renders these transactions identical to other transactions, once settled on the blockchain.

Maxwell has proposed that until the developers and community do not give a final go-ahead for the implementation of MAST, he wants to roll out his other pet project called Schnorr signatures or aggregate signatures. “There has been a lot of hype about smart contracts, but real and meaningful usage of them hasn’t caught up with that hype yet, ” said Maxwell. He further added,

“For real smart contracts like these to gain wide use, a lot of additional work is required especially in the area of providing good user interfaces to use them.”