Bitcoin Optech's avatar
Bitcoin Optech
_@bitcoinops.org
npub1hkuk...432p
We provide weekly newsletters, workshops, case studies, and research for the #Bitcoin community.
Bitcoin Optech newsletter #417 is here: - describes a draft BIP for relaying stale block tips between peers - summarizes a draft BIP for cross-input signature aggregation - examines a design for attaching post-quantum witness data - links to a discussion of post-quantum output types - summarizes discussions around transaction expiry - points to a proposal for layered quantum recovery of hashed addresses - describes a proposal to add a prunable block region for arbitrary data - Optech Newsletter #417 Podcast Ram and w0xlt posted to the Bitcoin-Dev mailing list about the proposal for an opt-in P2P message for relaying stale tips between peers... Fabian Jahr posted to the Bitcoin-Dev mailing list a draft of BIP460 for transaction-wide cross-input signature aggregation (CISA) of taproot-style keypath spends... Pieter Wuille posted to Delving Bitcoin a design for attaching post-quantum witness data without repeating all of segwit’s deployment costs... Pieter Wuille opened a Delving Bitcoin thread to centralize discussion of post-quantum output types... Josh Doman posted to Delving Bitcoin a construction for expiring HTLCs without free relay, then generalized it in a follow-up on input-triggered transaction expiry... Shinobi posted to the Bitcoin-Dev mailing list and cross-posted to Delving Bitcoin a layered recovery plan for coins secured by hashed address types... MrHash posted to Delving Bitcoin companion BIP drafts for Segregated Data, a soft fork that would add a prunable, script-isolated block region for arbitrary data carriage... Bitcoin Optech will host an audio recap discussion of this newsletter streaming live on X/Twitter Tuesday at 16:30 UTC.
Rob Hamilton, PortlandHODL, Chandra Pratap, and fabohax joined Optech to discuss Newsletter #416: - Move funds secured by COLDCARD-generated keys - Wallets generated by COLDCARD at risk of theft - Disclosure of two DoS vulnerabilities in Core Lightning - Proof of concept for a zero-knowledge proof of reserves - Selected Q&A from the Bitcoin Stack Exchange - And more You can listen on our website: Fountain: https://fountain.fm/show/nnl3QRRuNyxBry8BBoH4 Spotify: Apple Podcasts:
Bitcoin Optech newsletter #416 is here: - warns about a severe vulnerability affecting wallets generated by COLDCARD signing devices - summarizes the disclosure of two denial-of-service vulnerabilities in Core Lightning - describes a proof of concept for a zero-knowledge proof of reserves - summarizes popular Q&A from Stack Exchange - Optech Newsletter #416 Podcast If you used a COLDCARD to generate a wallet, any funds received by that wallet are at risk of theft and should be carefully moved to an unaffected wallet as soon as possible... On 30 July 2026, some Bitcoin users discovered that funds from their COLDCARD wallets had been stolen in a series of unexpected transactions on 29 July. Over the course of the day, a bug was identified in the firmware of the COLDCARD that causes wallets to be generated with insufficient entropy. As of this writing, estimated losses exceed 1,000 BTC, a figure that may continue to rise as the situation develops... Chandra Pratap posted to Delving Bitcoin about two denial-of-service (DoS) vulnerabilities he found in Core Lightning... fabohax posted about zkPoH (“zero-knowledge proof-of-hodl”), a proof of concept for a non-custodial proof of reserves system for Bitcoin... Selected Q&A from Bitcoin Stack Exchange - What is Bitcoin’s objective definition of transaction neutrality? - Why does BIP110’s decentralization benefit not outweigh its impact on transaction neutrality? - Why does BIP110 require a 55% signaling threshold if its nodes reject non-signaling blocks? - Why use ElligatorSwift encoding in BIP324? - Was the OP_SUCCESSx reservation in BIP342 designed with specific opcode families in mind? - What is the difference between the long-term feerate and the discard feerate? - What is the quickest method for migrating a legacy wallet to a descriptor wallet on a pruned node? - Is there historical data on orphan/stale block rates during high-fee periods? Bitcoin Optech will host an audio recap discussion of this newsletter streaming live on X/Twitter Tuesday at 16:30 UTC.
PSA: Wallets generated by Coldcard at risk! Wallets generated by Coldcard Mk3 using a firmware version 4.0.1 (March 2021) or later, up to the latest version may be vulnerable to theft, unless used in combination with a strong passphrase or entropy was generated externally. Please see the Coinkite security advisory (https://blog.coinkite.com/coldcard-mk3-seed-generation-warning/). The attack is easy to reproduce with LLM assistance. There are reports that Mk2, Mk4, and Mk5 may be affected by (weaker) variants of the same vulnerability. If your wallet may be affected, please carefully move your funds to an unaffected wallet ASAP.
Fabian Jahr, Kruw, and Mojo joined Optech to discuss Newsletter #415: - Draft BIP for full aggregation of BIP340 signatures - Changes to services and client software including Wasabi, Coinswap, Go secp256k1, an ASMap dashboard, Wavelength - And more You can listen on our website: Fountain: https://fountain.fm/episode/DwKaI4UBnN19MQJpcEPx Spotify: Apple Podcasts:
Bitcoin Optech newsletter #415 is here: - describes a draft BIP for full aggregation of BIP340 signatures - summarizes changes to services/client software - Optech Newsletter #415 Podcast Fabian Jahr posted to the Bitcoin-Dev mailing list about a new draft BIP for full aggregation of BIP340 schnorr signatures, a standard for the DahLIAS aggregate signature scheme... Changes to services and client software: - Wasabi Wallet 2.8.0 released - Coinswap v0.2.2 released - Go secp256k1 library announced - ASMap dashboard announced - Wavelength alpha released Bitcoin Optech will host an audio recap discussion of this newsletter streaming live on X/Twitter Tuesday at 16:30 UTC.
Bitcoin Optech newsletter #414 is here: - describes a new project to apply formal verification to the Bitcoin protocol - Bitcoin Core 30.3, Bitcoin Core 29.4 - Optech Newsletter #414 Podcast Keagan McClelland posted to the Bitcoin-Dev mailing list and Delving Bitcoin about his effort to formally verify the Bitcoin protocol... Bitcoin Optech will host an audio recap discussion of this newsletter streaming live on X/Twitter Tuesday at 16:30 UTC.
Bitcoin Optech newsletter #413 is here: - describes research into using fountain codes to allow pruned nodes to contribute to initial block download - Bitcoin Core 31.1, LND v0.20.2-beta - Optech Newsletter #413 Podcast Lucas Lima posted to Delving Bitcoin about his latest research on using fountain codes to allow pruned nodes to contribute to Initial Block Download (IBD), without significantly increasing their storage requirements... Bitcoin Optech will host an audio recap discussion of this newsletter streaming live on X/Twitter Tuesday at 16:30 UTC.
Conduition and Jeremy Rubin joined Optech to discuss Newsletter #412: - Benchmarking SLH-DSA STARK aggregation - Bird of Prey 2 (BoP-2) non-malleable schnorr and PQ signatures - Lattice-based signatures - Public key recovery for P2MR EC leaves - Aligning privacy incentives in P2MR - Prohibit merkle internal node preimages that encode minimal 64-byte transactions - Triggering EC disabling with a NUMS point spend or hashrate majority - And more You can listen on our website: Fountain: https://fountain.fm/episode/y6XkElTaP2wZFzmAsY8n Spotify: Apple Podcasts:
Bitcoin Optech newsletter #412 is here: - links to benchmarking around SLH-DSA STARK aggregation - points to discussion of a paper on constructing hybrid strongly-unforgeable signature schemes - examines lattice-based PQ signatures - describes a proposal for public key recovery for P2MR EC leaves - summarizes a thread on aligning privacy incentives in P2MR - describes and alternative to banning all 64-byte transactions - summarizes a proposal to trigger EC disabling with a NUMS point spend or hashrate majority - Optech Newsletter #412 Podcast Remix7531 posted to the Bitcoin-Dev mailing list his benchmark results for aggregating many SPHINCS signature verifications into a single STARK proof... Pieter Wuille posted to Delving Bitcoin about a EuroCrypt 2026 paper on constructing hybrid strongly-unforgeable signature schemes from a schnorr-like scheme and an arbitrary post-quantum signature scheme... Nikita Karetnikov posted to Delving Bitcoin and cross-posted to the Bitcoin-Dev mailing list about a Blockstream blog post comparing post-quantum signature families, where lattice-based schemes appear favorable on size and functionality... starius posted to Delving Bitcoin a proposal to add a recoverable elliptic curve (EC) key leaf type to BIP360 (P2MR). The idea is to recover the EC public key from the schnorr signature... Conduition posted to the Bitcoin-Dev mailing list a proposed BIP360 (P2MR) change to require every P2MR control block to include at least one 32-byte merkle authentication path (i.e. ban depth-zero script trees)... Jeremy Rubin posted to the Bitcoin-Dev mailing list a draft BIP proposing an alternative to the consensus cleanup (BIP54) rule making 64-byte witness-stripped transactions consensus-invalid... Pieter Wuille wrote to the Bitcoin-Dev mailing list about codifying the expected future disabling of elliptic curve (EC) spending paths within new post-quantum output types such as BIP360 (P2MR) and P2TRv2... Bitcoin Optech will host an audio recap discussion of this newsletter streaming live on X/Twitter Tuesday at 16:30 UTC.
Nishant Bansal and Matthew Zipkin joined Optech to discuss Newsletter #411: - LND zero-timestamp gossip DoS disclosure - Removal of the libevent library in Bitcoin Core - Selected Q&A from the Bitcoin Stack Exchange - And more You can listen on our website: Spotify: Apple Podcasts:
Bitcoin Optech newsletter #411 is here: - describes the responsible disclosure of a denial-of-service vulnerability that affected older versions of LND - summarizes popular Q&A from Stack Exchange - Optech Newsletter #411 Podcast Nishant Bansal posted to Delving Bitcoin disclosing a denial-of-service vulnerability he discovered through state-machine fuzzing of LND’s gossip handling... Selected Q&A from Bitcoin Stack Exchange - Is it a bug that OP_IF is part of the tapscript opcodes? - Why would forbidding OP_IF in tapscript be a problem? - Does a softfork always succeed? - How to set up Bitcoin Core to mine a valid block after the BIP110 activation in August 2026? - Are BIP110 blocks on a branch with lower difficulty valid? - What is the story behind Bitcoin test networks? - Why was -datacarriersize redefined in 2022, and why was the 2023 proposal to expand it not merged? - Are chains of 26 unconfirmed transactions prohibited by the wallet in Bitcoin Core 31.0? - Are there changes in Bitcoin Core 29.0 that affect memory usage? - What is Bitcoin Core’s release schedule? Bitcoin Optech will host an audio recap discussion of this newsletter streaming live on X/Twitter Tuesday at 16:30 UTC.
rkrux, Roland Bewick, and Steven Roose joined Optech to discuss Newsletter #410: - Discussion of removing RBF signaling from wallet transactions - Changes to services and client software including Sparrow, Alby, JoinMarket NG, Bark, Arké, Noah - And more You can listen on our website: Spotify: Apple Podcasts:
Bitcoin Optech newsletter #410 is here: - summarizes a discussion about wallets removing opt-in replace-by-fee signaling from the transactions they create - summarizes changes to services/client software - Optech Newsletter #410 Podcast rkrux posted to the Bitcoin-Dev mailing list proposing that wallets stop signaling opt-in RBF in the transactions they create... Changes to services and client software: - Sparrow Wallet 2.5.0 adds silent payments receiving - Bark live on Bitcoin mainnet - Arké Ark wallet announced - Noah Ark wallet announced - Alby Hub v1.23.0 released - JoinMarket NG 0.32.0 released Bitcoin Optech will host an audio recap discussion of this newsletter streaming live on X/Twitter Tuesday at 16:30 UTC.
Bitcoin Optech newsletter #409 is here: - describes a draft BIP to replace the testnet4 test network with a successor - Optech Newsletter #409 Podcast Pol Espinasa posted to the Bitcoin-Dev mailing list a draft BIP, co-authored with Fabian Jahr, to replace testnet4 with testnet5... Bitcoin Optech will host an audio recap discussion of this newsletter streaming live on X/Twitter Tuesday at 16:30 UTC.
Bitcoin Optech's avatar
Bitcoin Optech 2 months ago
Pyth and Ademan joined Optech to discuss Newsletter #408: - Post-quantum BIP324 - QR signing payloads for miniscript wallets - CTV-only vault proof of concept - Post-quantum Lightning discussion - Quantum attack game theory - BIP54 64-byte transactions and potential legitimate uses - And more You can listen on our website: Spotify: Apple Podcasts:
Bitcoin Optech's avatar
Bitcoin Optech 2 months ago
Bitcoin Optech newsletter #408 is here: - summarizes ideas to make BIP324 transport encryption quantum secure - describes a proposal to standardize QR-based signing payloads for miniscript wallets - links to a CTV-only vault proof of concept - outlines points from a post-quantum Lightning thread - summarizes a quantum attack game theory post - points to discussion of 64-byte transactions and potential uses - Optech Newsletter #408 Podcast Olaoluwa Osuntokun posted to the Bitcoin-Dev mailing list his thoughts on possible upgrades needed to make BIP324 quantum secure... Pyth posted to Delving Bitcoin a proposal to standardize the data payloads exchanged between wallet coordinators and air-gapped signing devices over QR codes when using miniscript-based spending policies... Ademan announced on Delving Bitcoin the 0.1.0 release of his CTV (BIP119) vault project called MCCV (More Complicated CTV Vault)... Olaoluwa Osuntokun (roasbeef) posted to Delving Bitcoin a breakdown of how a post-quantum Lightning Network might look... Jameson Lopp posted to Delving Bitcoin his blog post about the game theory of a quantum attack... Jeremy Rubin wrote to the Bitcoin-Dev mailing list about potential legitimate uses for 64-byte witness-stripped transactions... Bitcoin Optech will host an audio recap discussion of this newsletter streaming live on X/Twitter Tuesday at 16:30 UTC.