Issue #907: Bitcoin Core v0.21.0 has been released

Bitcoin Core v0.21.0 was released earlier this morning. It's a good day for Bitcoin because this release comes with a number of updates that improve UX and privacy, harden the P2P layer, and make the testing suite more robust for Bitcoin Core users.

A couple of notable changes that will improve privacy and security at the P2P layer are the way transactions are broadcast and rebroadcasted to the network and the addition of 'anchors.dat' to increase the potential for node eclipse attacks. The change to transaction (re)broadcasting improves user privacy by rendering a common timing heuristic obsolete and making it harder to tie a broadcasted transaction to a particular IP address.

Descriptor wallets have also been added to Core, which will dramatically improve wallet management UX. Bitcoin Core users will now be able to label and separate different wallets with different spending conditions. UTXOs tied to addresses that only need a single signature to move, UTXOs locked in multisig wallets, and UTXOs locked in wallets with other types of unique spending conditions can now be presented in distinct ways to reduce the confusion and stress that can come with UTXO management.

BIP 339 has been merged and activated in v0.20.0, which adds a new way for transactions to be relayed across the P2P network. Now nodes will be able to relay the wtxid associated with a certain transaction instead of just a txid. Apparently this will help the efficiency of transaction relay and eliminate the possibility of transaction witnesses being malleated with a txid.

anchors.dat being added to the protocol will help individual nodes protect themselves from being eclipse attacked after having their node go offline. It does this by storing two previous peers in the anchors.dat file and reconnecting with them upon reboot. This reduces the chances of being fed bad data from a group of malicious peers. If you can assume that the two peers in the anchors.dat file aren't malicious themselves.

There's a lot of other cool things included in this update including support for Tor v3, Taproot being merged, and Signet officially being added. I recommend you freaks go check out the specs if you get a chance.