Taproot is the next major upgrade for the Bitcoin protocol
Please upgrade your Bitcoin node by November 12th!

Features

Improved Privacy: Taproot transactions usually look the same, even with advanced smart contracts or multiple signers.
Better Efficiency: "Schnorr" signatures are used to reduce the data usage and cost of both simple and complex transactions.
Upgradable: Future improvements to Bitcoin can be cleanly made Taproot-compatible.
Opt-in Usage: Current Bitcoin transactions continue to work the same.
 
 

Bitcoin Core 0.21.0-based Taproot Client 0.1

Download Bitcoin Core-based Taproot Client for Windows
Download Bitcoin Core-based Taproot Client for macOS
Install Bitcoin Core-based Taproot Client for Ubuntu
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Security notice

Please note: When installing this or any other app, you should verify your download is the authentic program, and not intercepted by a virus. Always verify the correct digital signature on any downloads to avoid malware. Bitcoin Core-based Taproot Client is signed by bitcoinmechanicca@protonmail.com and Luke Dashjr. You should ideally download PGP keys from at least two independent sources and ensure they match. Click here for a tutorial on how to verify the OpenPGP signature!

 

FAQ

Taproot Itself

How does Taproot improve privacy?
First, "Schnorr" signatures allow making multiple signers indistinguishable from a single signer. Using advanced math, the digital signatures of all relevant parties can be added together to produce a single signature valid for the transaction. The coins' key can also optionally be made to commit to a smart contract (one or more), in a manner which is indistinguishable unless the recipients wish to reveal it. Since the outcome of smart contracts is well-defined, ordinarily there is no need to reveal it because both parties can see the outcome and simply agree, therefore utilising a 2-of-2 multiple-signer option instead.
How is Taproot more efficient?
Since Bitcoin nodes typically only need to verify a single digital signature for each transaction (see above question on privacy for details on how this is achieved) instead of potentially many, not only do transactions require less high-cost blockchain space, but they also reduce the overall load required to run a node. Additionally, thanks to the ability to add "Schnorr" signatures together, verification can be further optimised by adding all the signatures in the block and verifying them all together once.
In what way is Taproot upgradable?
Taproot keys represent a number of multiple-signer combinations as well as one or more smart contracts. Each smart contract specifies a version number, which future upgrades can define to provide a new smart contract language or extensions, while still using the same overall Taproot format (including privacy benefits and being generally indistinguishable from older Taproot transactions and smart contracts).
What makes Taproot opt-in?
While all protocol upgrades for Bitcoin require community involvement via running software, and therefore all nodes must upgrade to retain their full security, Taproot does not modify any existing rules of Bitcoin, only adds new ones to the previously reserved and unusable "witness version 1" (not to be confused with the existing "witness version 0" defined by Segwit in 2017). Therefore, old nodes will remain compatible (with security comparable to light wallets), existing bitcoins in circulation today are entirely unaffected, and nobody needs to use Taproot's new features until and unless they choose to.

Activation Process

Who decided to activate Taproot?
Taproot was first proposed to the community in 2018, specifics finished in early 2020, and review completed over several months into late 2020. During this time and thereafter, no serious objections to the proposal have been raised, and general sentiment observed in the community has been positive. Therefore, this software has been released to the community with the assumption that there is a general consensus for activating Taproot. However, no mere software release can actually change the Bitcoin protocol, and the final activation can occur only by Bitcoin users adopting this (or compatible) software.
What if I oppose Taproot?
The good news is that you do not need to use it (Taproot is an opt-in feature). The bad news is that a lone objection this late is not likely to change anything others do unless it has a very good argument. However, if you do indeed have a good argument, please e-mail it to the Bitcoin development mailing list ASAP. Also note that so long as the rest of the community proceeds toward activation, it will still activate, and you will need to upgrade yourself to retain full security. If your objection is firm enough, regardless of reason, you can, however, create or support a counter-activation to reject activation of Taproot by making blocks with bit 2 invalid before they reach 90% (see BIP 8 for details).
Why do I need to upgrade for Taproot?
Bitcoin is a decentralised system, with the rules and security enforced by its users. Without an economic majority of users enforcing the new Taproot rules, it cannot be safely used by anyone.
What happens if I don't upgrade in time?
As early as November 12th, it is possible that Taproot may become active. If you have not upgraded before Taproot activates, or 2022 October 14th, whichever is earlier, your node will no longer be fully secure and you may become vulnerable to certain attacks. However, Taproot will only activate early (prior to 2022 October 14th) if miners are prepared to protect slow upgraders from these attacks. In such a situation, your node is trusting and relying on miners until you do upgrade.
Do only miners need to upgrade?
No. Miners play an important role in Bitcoin by preventing "double spending", but the protocol is primarily enforced by non-miners.
What role do miners have in activating Taproot?
In order to ensure all users have upgraded, softforks typically need a long period of time before activation - over a year (2022 October 28th in this case). However, so long as a significant majority of users have upgraded, the network security overall can be ensured, while miners can be entrusted with the protection of only the remaining minority who need more time. Therefore, if miners upgrade sooner, a shorter time period can be used 6 months (for Taproot, 2021 November 12th).
Is this a User-Activated SoftFork (UASF)?
No. This activation uses BIP 8 to ensure a safe and clean activation coordinated by miners. It is therefore a Miner-Activated SoftFork (MASF). However, it does not give miners the additional power to veto Taproot, and should miners neglect to coordinate an early activation, will still activate Taproot during late 2022. In that fallback scenario, it is accurate to consider it to have become a User-Activated SoftFork (UASF). Miners have publicly indicated that they also support Taproot themselves, so it is expected that activation under the normal MASF routine should proceed smoothly, and no UASF fallback will be needed.

Taproot Client Software

Who maintains the Taproot Client software?
The software code has been written and reviewed by several Bitcoin Core developers. The releases are, however, maintained by three community members, Bitcoin Mechanic, Shinobi, and stortz. Luke Dashjr has helped advise and make sure things get done properly and safely.
How is the software different from regular Bitcoin Core?
Unmodified Bitcoin Core includes the code to implement Taproot, but disabled. When Taproot activates, it will not enforce the new rules, and may fall out of consensus. Update 2021-05-01: An alternate client being called simply "Bitcoin Core 0.21.1" was just released that will remain in consensus if and only if miners signal within the first 3 months. It is still recommended to run the dedicated Taproot Client release.
 
 

Technical details

Type:softfork
Specification: BIP 341 (witness)
BIP 342 (scripts)
Earliest activation:709632 (2021 November 12th*)
Latest activation:762048 (2022 November 11th*)
Activation method:BIP 8
API name:taproot
Signal bit:2
Start Height:681408 (2021 April 30th)
Timeout Height:760032 (2022 October 28th)
Threshold:90%
Lockin On Timeout:Yes

* Activation is based on Bitcoin block height, so calendar dates are approximate