Bitcoin Core 0.21.0 released

On January 14, the updated Bitcoin Core client was released. Support for Tor Network V3 addresses and descriptor wallets was added; bugs were fixed and performance improved. The work was led by 100 developers over six months.

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

— Bitcoin Core Project (@bitcoincoreorg) January 14, 2021

Descriptor wallets

These wallets use scripts instead of keys, which provides greater flexibility on the backend. The scripts can include private keys, which is typical of traditional wallets, but they are not limited to them.

Descriptor wallets allow users to classify unspent transaction outputs (UTXOs) based on the types of conditions required to spend them. For example, one wallet could be used for receiving UTXOs that are spendable with a signature, and another — multisignature. The innovation foreshadows future hardware-wallet integration.

This change is aimed primarily at developers who build software on top of the Bitcoin Core kernel. Users who already have a Bitcoin Core wallet will not be affected. For those planning to run a node, an option to select a descriptor wallet will now be available. By 2023, traditional wallets may be fully replaced by the new type. заменить

Block filtering

The release introduces a new block-filtering system for light clients that do not store the full history of Bitcoin transactions and download only a portion of the blockchain using so-called Bloom filters. The filters query data from relatively random nodes, but they can reveal all of a user\’s addresses.

To address the issue in Bitcoin Core 0.21.0 they implemented an alternative mechanism known as “client-side block filtering” (BIP 157/158). Instead of light wallets generating filters to send to full nodes, the full nodes generate them for each block and send them to light clients on demand.

Another privacy risk stemmed from the settings for relaying transactions, which occurred every 15 minutes until inclusion in a block. Bitcoin Core 0.21.0 reduces the frequency at which it attempts to rebroadcast transactions to once every 12–36 hours. This makes tracing the identity of a transaction more difficult.

Tor V3 support

As part of the recent Tor protocol upgrade, V3 addresses were introduced. Compared with the previous version, they feature more robust cryptography and less information disclosure. By 15 October 2021, developers will release new client versions that disable V2 addresses.

Bitcoin Core 0.21.0 added support for a new address format, enabling nodes to connect when joining private networks.

Schnorr/Taproot update

The Schnorr/Taproot upgrade will be the first in the Bitcoin protocol since the launch of Segregated Witness (SegWit) in August 2017. Activation timelines are unknown, but the code has already been added to Bitcoin Core 0.21.0. This means it will no longer be subject to changes. Application developers can begin building software around the upgrade.

What is Taproot?

There is currently no activation logic required to enable it in the clients. It may be included in one of the upcoming minor Bitcoin Core releases in the coming months. In December Taproot upgrade support reached 91% of the total Bitcoin hashrate.

New testnet

The Bitcoin network has also gained a new testnet, Signet. It differs from its predecessors in centralised control, which increases reliability.

ForkLog previously published a translation of Aaron van Wirdum’s article explaining how Taproot works and why this development will strengthen Bitcoin.

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