Bitcoin’s consensus layer has remained unchanged for over two years now. Since Segregated Witness (SegWit), which activated[1] in August 2017, no hard fork or soft fork protocol upgrades have been deployed at all*, marking Bitcoin’s longest stretch without consensus forks so far.
But this stretch may soon come to an end: several backward-compatible soft forks are currently in development. Optimistically, some of them may go live in 2020 — if they gather sufficient support from the Bitcoin ecosystem.
These could be Bitcoin’s protocol upgrades in the new year … or perhaps in the new decennium.
Schnorr/Taproot/Tapscript
Schnorr signatures are considered by many cryptographers to be the best type of cryptographic signatures in the field. They offer a strong level of correctness, do not suffer from malleability, are relatively fast to verify and, perhaps most interestingly, allow for math to be performed with them. To name one concrete benefit for Bitcoin: Several signatures can be aggregated into a single signature, which could, for example, economically incentivize privacy-enhancing CoinJoin transactions[2].
Adding Schnorr signatures to the Bitcoin protocol has been a work in progress for some time now. But over the past year, developers working on a Schnorr signatures[3] proposal, like Blockstream developers Pieter Wuille and Jonas Nick and Xapo's Anthony Towns, revealed even more ambitious plans. Schnorr signatures will be proposed as part of a bigger soft fork protocol upgrade called Taproot[4], a proposal by Bitcoin Core contributor Gregory Maxwell, which was itself inspired by an older proposal called MAST[5] (Merkelized Abstract Syntax Tree).
(Fractions of) bitcoin can be locked up in such a way that they can be spent under several different conditions, for example requiring timelocks, secret numbers of several participants to agree to unlock
