Bitcoin Core reaches version 27.0: improvements focused on security, efficiency, and transaction management.
Version 27.0 of Bitcoin Core is now available, featuring a series of updates and technical changes designed to improve both the functionality and security of the Bitcoin network.
Obsolescence of “libbitcoinconsensus”
In version 27.0, the “libbitcoinconsensus” library is being deprecated and will be permanently removed with version 28.0. This library, used for nearly ten years, will no longer receive further updates and will be replaced by the “libbitcoinkernel” library for a more stable interaction with the UTXO set for transaction and block validation.
New format of the mempool.dat file
In terms of security, the format of the mempool.dat file, which stores unconfirmed transactions, has been modified. The new format is designed to resist alterations by external software such as antivirus programs. An option to revert to the old format is available for those who need to downgrade.
Transport layer update
The update implements version 2 of BIP324 by default, improving the connection protocols across the network. BIP324 version 2 introduces a new P2P transport protocol that features opportunistic encryption, a mild bandwidth reduction, and the ability to negotiate upgrades before exchanging application messages.
New mempool policy
The update includes the introduction of Topologically Restricted Until Confirmation (TRUC) transactions. This new policy, currently only applicable on the testnet, aims to improve the incentive structure around transaction replacements and fee bumping reliability by applying constraints on the spending of unconfirmed outputs.
Updates on RPC and external signing
Finally, changes have been made to the “addnode” RPC to align with the new default setting of the version 2 transport layer.
Support for external signing on Windows systems has been temporarily suspended due to dependencies on an outdated library. Re-enabling the functionality is planned once an alternative library is integrated.
