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2023-10-25 10:57:03

Bitcoin Optech on Nostr: Bitcoin Optech newsletter #274 is here: - describes the replacement cycling attack ...

Bitcoin Optech newsletter #274 is here:

- describes the replacement cycling attack against HTLCs used in LN and other systems, examines the mitigations deployed, and summarizes proposals for additional mitigations
- notes a bug affecting a Bitcoin Core RPC
- describes research into covenants with minimal changes to Bitcoin Script
- announces a proposed BIP for an OP_CAT opcode
- summarizes popular Q&A from Stack Exchange
- Optech Newsletter #274 Recap on Twitter Spaces

https://bitcoinops.org/en/newsletters/2023/10/25/

As briefly mentioned in last week’s newsletter, Antoine Riard posted to the Bitcoin-Dev and Lightning-Dev mailing lists about a responsibly disclosed vulnerability affecting all LN implementations.

It’s possible to use transaction replacement to remove one or more inputs of a multi-input transaction from node mempools...
https://bitcoinops.org/en/newsletters/2023/10/25/#replacement-cycling-vulnerability-against-htlcs

Several mitigations have been deployed by LN implementations for replacement cycling...
https://bitcoinops.org/en/newsletters/2023/10/25/#deployed-mitigations-in-ln-nodes-for-replacement-cycling

There have been over 40 separate posts made to the Bitcoin-Dev and Lightning-Dev mailing lists in response to the disclosure of the replacement cycling attack. Suggested responses included proposed additional mitigations...
https://bitcoinops.org/en/newsletters/2023/10/25/#proposed-additional-mitigations-for-replacement-cycling

Fabian Jahr posted to the Bitcoin-Dev mailing list to announce that a bug had been discovered in Bitcoin Core’s calculation of the hash of the current UTXO set...
https://bitcoinops.org/en/newsletters/2023/10/25/#bitcoin-utxo-set-summary-hash-replacement

Rusty Russell posted to the Bitcoin-Dev mailing list a link to some research he has performed about using a few simple new opcodes to allow a script being executed in a transaction to inspect the output scripts being paid in that same transaction, a powerful form of introspection...
https://bitcoinops.org/en/newsletters/2023/10/25/#research-into-generic-covenants-with-minimal-script-language-changes

Ethan Heilman posted to the Bitcoin-Dev mailing list a proposed BIP to add an OP_CAT opcode to tapscript...
https://bitcoinops.org/en/newsletters/2023/10/25/#proposed-bip-for-op-cat

Selected Q&A from Bitcoin Stack Exchange:

- How does the Branch and Bound coin selection algorithm work?
- Why is each transaction broadcast twice in the Bitcoin network?
- Why are OP_MUL and OP_DIV disabled in Bitcoin?
- Why are hashSequence and hashPrevouts computed separately?
- Why does Miniscript add an extra size check for hash preimage comparisons?
- How can the next block fee be less than the mempool purging fee rate?
https://bitcoinops.org/en/newsletters/2023/10/25/#selected-qa-from-bitcoin-stack-exchange

Bitcoin Core 26.0rc1 is a release candidate for the next major version of the predominant full node implementation...
https://bitcoinops.org/en/newsletters/2023/10/25/#bitcoin-core-26-0rc1

Bitcoin Optech will host an audio recap discussion of this newsletter with special guests Fabian Jahr and Ethan Heilman on Twitter Spaces Thursday at 15:00 UTC. Join us to discuss or ask questions!
https://twitter.com/i/spaces/1rmxPMZzbYQKN
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