Popular Bitcoin Core client version 0.21.0 was released

An updated version of the Bitcoin Core client was released on January 14. Added support for V3 addresses of Tor Network, descriptor wallets, fixed bugs and improved performance.

The work was conducted by 100 developers during half a year.

Bitcoin Core 0.21.0 was released
It is available from https://t.co/jnWN8LRX75
Release mail: https://t.co/6dFNUj3K4d

Descriptor wallets

The change is aimed primarily at developers who create software on top of the bitcoin core. Users who already have a Bitcoin Bank wallet will not be affected by the change. For those who plan to launch a node, there will now be an option to choose a descriptive wallet. By 2023, traditional wallets may be completely replaced with the new type.

These wallets use scripts instead of keys, which provides more flexibility in the backend. Scripts can also include private keys, which is inherent to traditional wallets, but they are not limited to them.

Descriptive wallets allow users to classify unspent transaction outputs (UTXOs) based on the types of conditions needed to use them. For example, one wallet can be used to accept UTXOs validated with a signature and another wallet can be used for multi-signature transactions. The innovation foreshadows future integration of hardware wallets.

Blockchain filtering

The release introduced a new block filtering system for light clients that do not store the full history of bitcoin transactions and load only a certain part of the blockchain using so-called Bloom filters. The latter request data from relatively random nodes, but in doing so can expose all of a user’s addresses.

To solve the problem, Bitcoin Core 0.21.0 implemented an alternative mechanism called „client-side compact block filtering“ (BIP 157/158). Instead of light wallets creating filters to send to full nodes, the latter do this for each block and send them to light clients on demand.

Another threat to user privacy was the setting of transaction retransmissions, which were done every 15 minutes before they were included in the block. Bitcoin Core 0.21.0 reduces the frequency with which it attempts to retransmit transactions to one action every 12-36 hours. This makes it difficult to analyze the identity of a particular transaction.

Tor V3 support.

As part of a recent update to the Tor protocol, V3 addresses were introduced. Compared to the previous version, they have more secure cryptography and less disclosure. By October 15, 2021, developers will release new versions of clients that will disable V2 addresses.

Bitcoin Core 0.21.0 added support for a new address format that allows nodes to establish connections when connecting to private networks.

Schnorr/Taproot update

The Schnorr/Taproot update will be the first in the bitcoin protocol since the launch of Segregated Witness (SegWit) in August 2017. The timing of the update’s activation is unknown, but the code has already been added to Bitcoin Core 0.21.0, meaning that it will no longer be subject to any changes. App developers can start building software around the update.

For now, the clients don’t have the activation logic needed to launch. It may be included in one of the smaller Bitcoin Core releases in the coming months. Support for the Taproot update reached 91% of Bitcoin’s total hash rate in December.
New testnet.

The bitcoin network also got a new testnet, Signet. It is distinguished from its predecessors by its centralized control, which increases reliability.

As a reminder, ForkLog published a translation of Aaron van Wirdum’s article on the principles of Taproot, explaining why this solution will make bitcoin stronger.