<style> .reveal { font-size: 24px; } . reveal h1 h2 { font-family: "League Gothic", Impact, sans-serif; color: #eee8d5; font-family: "League Gothic", Impact, sans-serif; line-height: 0.9em; letter-spacing: 0.02em; text-transform: uppercase; text-shadow: none; } .reveal ul { font-size: 5 em ; line-height: 1.2 em ; } .reveal pre code { font-size: 0.7em ; margin: 0px 60px 0px 60px; .reveal p { line-height: 1 em ; } .reveal blockquote { font-size: 1 em ; line-height: 1.2 em ; } </style> <img src="https://hackmd.io/_uploads/HkEB3VdmT.jpg" width=1024> <font size="7">FROST CLI #Gordian Meeting 9/6/25</font> --- ## <img src="https://i.imgur.com/QyDl5nK.png" width="192" height="192"></br> What is Blockchain Commons? <font size=6> * We are a community interested in self-sovereign control of digital assets. * We bring together stakeholders to collaboratively develop interoperable infrastructure. * We design decentralized solutions where everyone wins. * We are a neutral "not-for-profit" that enables people to control their own digital destiny. </font> --- Thank you to our FROST Sponsor!  Become a sponsor! Mail us at team@blockchaincommons.com --- ## <img src="https://i.imgur.com/QyDl5nK.png" width=50 height="50">Two Great Tools <font size=6> * We've been working with two great tools * ZF FROST * https://frost.zfnd.org/ * Bitcoin Dev Kit (BDK) * https://bitcoindevkit.org/ </font> --- ## 🧩 Our Biggest Puzzle <font size=6> * How Do We combine ZF FROST & BDK for PSBT Signing? * ZF FROST Needed Secp256K1-TR Ciphersuite * BDK Needed to Apply Signature - But Also Needed a "Tweak" to Avoid a Taproot Attack - Transaction hash must be extracted - Key Material is tweaked - Signature is reinserted </font> --- ## ❄️ ZF FROST <font size=6> * We Built on Existing FROST CLI Tools * https://github.com/ZcashFoundation/frost-tools * Submitted PR for Secp256K1-TR Ciphersuite * https://github.com/ZcashFoundation/frost-tools/pull/537 * Also have a branch which does Taproot tweak * https://github.com/BlockchainCommons/zcash-frost-tools/pull/2 </font> --- ## 🧰 BDK <font size=6> * Extracting hash wasn't available in CLI. * (Tweaking is an external process.) * Reinserting signature wasn't available in CLI. * Had to use libraries & write two tools to extract & reinsert sig * But: * It's unclear who should be tweaking. * There may be privacy concerns for tweaking BIP-32 derivations. * Tweaking may not be necessary with FROST DKG. * More on this all after our demo! </font> --- ## <img src="https://i.imgur.com/QyDl5nK.png" width=50 height="50">Blockchain Commons Demo <font size=6> * Demo: * Spend Taproot (P2TR) Bitcoin * On a private regtest network * Using a 2‑of‑3 FROST signature * We will: * Create 3 keyshares with Trusted Dealer * Create a PSBT * Run `sighash-helper` to get Taproot key‑path sighash * Sign with FROST * Inject signature with `psbt-sig-attach` * Transmit! * Over to Wolf! </font> --- ## ❄️ ZF FROST DKG Open Questions <font size=6> * We were unable to get the ZF Distributed Key Generation (DKG) server to work, it may be a few steps behind the TD (Trusted Dealer) code. * There doesn't seem to be any standards for the DKG values. I don't believe any of the three DKGs we've tested can be used with a different FROST signing system. </font> --- ## ❄️ ZF FROST Open Questions <font size=6> **On PRs:** * What is the status of PRs to ZF FROST? * Does DKG make that Taproot tweak unnecessary? * Does it make sense to submit tweak PR? * Do we need to add optionality to tweak PR? **On Reviews:** * Did Schnorr BIP340 get security reviewed? * Will Zcash be doing more security reviews? </font> --- ## 🧰 BDK Open Questions <font size=6> * Should BDK expose retrieving hash? * SHould BDK expose re-inserting signature? * Who would we talk to to make this happen? * What if there is no requirement for tweak? * (e.g., with FROST DKG) </font> --- ## 🔮 Other Open Questions <font size=6> * Which party is really responsible for applying the Taproot tweak? * What should be done when it's not required? * Can we make the tweak more private by doing it at a different place? </font> --- ## ❄️ FROST is Coming! <font size=6> - We have a variety of resources and results from previous FROST workshops at: https://developer.blockchaincommons.com/frost/ - We will have more focused FROST meetings this fall. - If you'd like to present, let us know! - ***Library Implementers:*** Tell us about your tech and roadmap - ***Developers:*** Tell us about your needs and use cases </font> --- <img src="https://i.imgur.com/QyDl5nK.png" width="128" height="128"></br> www.BlockchainCommons.com <img src="https://avatars.githubusercontent.com/ChristopherA?s=195"> Christopher Allen (@ChristopherA)