Bitcoin Optech Newsletter #421

Bitcoin Optech Newsletter #421 highlights two key developments in the Bitcoin ecosystem. Firstly, `average_gary` presented an innovative idea on Delving Bitcoin for mining pools to pay miners using `silent payments` directly within the `coinbase transaction`. This method aims to significantly improve miner privacy by allowing them to share a static silent payment address through a `Stratum v2` encrypted channel, thereby avoiding the privacy risks associated with compromised pool databases holding `xpub`s. To adapt `BIP352 silent payments` for coinbase transactions, which lack input public keys, the pool generates an ephemeral private key to derive a sending public key (`A_send`). This `A_send` is then hashed with the block height to ensure uniqueness and prevent malicious grinding, before being included in the `coinbase scriptSig` for the miner to scan. Feedback is currently sought to formalize this proposal. Secondly, the newsletter reported the responsible disclosure of a critical `denial-of-service (DoS) vulnerability` impacting `Core Lightning (CLN)` nodes. `Erick Cestari` detailed this flaw on Delving Bitcoin, specifying that it affects `CLN versions prior to 25.09`.