Chaincode Delegation, quantum-proof signatures, shielded payments & more inside. Cryptape (npub186a…hd06)
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Chain Code Delegation: A Collaborative Custody Scheme for Private Access Control of Bitcoin Keys
Jurvis Tan shared his work with Jesse Posner on collaborative custody, called Chain Code Delegation. By withholding the BIP-32 chain code and only sharing the scalar tweaks at signing time, custodians can enforce certain policies like spend velocity controls without ever possessing an XPUB; granting them full view of a key’s entire key tree.
Without the chain code, custodians only hold a non-extended key pair. When signing is needed, the counterparty calculates and shares only the scalar tweak. Lacking the chain code, custodians cannot derive other child keys or recognize which public keys in a redeem script they didn't sign—meaning they only see the transactions explicitly given to them.
Beyond privacy benefits, chain code delegation limits security blast radius: without the chain code (or unpublished tweak), custodial keys can’t be used for unsigned UTXOs. Since tweaks are disclosed only just before spending, such UTXOs are typically consumed quickly. Even if the system is breached or a tweak leaked, attackers have only a narrow window to front-run the signature. Once the transaction is confirmed, the tweak becomes useless for future signatures.
Accept Bitcoin Donations Without a Server or Bitcoin Node
This tutorial presents a serverless, privacy-preserving, lightweight, and free method to accept on-chain Bitcoin donations via a website. The recipient doesn't need to run a server or Bitcoin node, nor use specialized software or command line tools. The only requirement is knowing how to create Bitcoin addresses and set up a serverless function (e.g., Cloudflare Workers, Netlify/Vercel Functions).
The author notes that while simple and free, this setup isn’t suitable for everyone—it doesn't support invoicing, point-of-sale, or CMS integrations.
Shielded CSV: Strengths and Challenges of a Bitcoin Privacy Protocol
Shielded CSV (and the sister protocol zkCoins) is a Bitcoin privacy protocol enabling users to send and receive payments without revealing identity, amounts, or network activity. It uses zero-knowledge proofs and client-side validation, supporting scalable Zcash-like anonymity. It embeds only 64-byte commitments into Bitcoin transactions and requires no soft fork.
The author of this article sees it as offering strong privacy with a lightweight blockchain footprint, though it comes with greater custodial requirements. True censorship resistance and trust minimization would still require supporting infrastructure—a trust-minimized bridge to and from Bitcoin.
Hash-Based Lamport Signatures: A Simple Quantum-Safe Option for Bitcoin
This study focuses on Lamport signatures—a hash-based, quantum-safe digital signature scheme first proposed in 1979. It demonstrates how quantum resistance can be achieved with minimal complexity, relying solely on hash functions and avoiding complex math or new algorithms.
The author argues that if Bitcoin moves toward quantum-safe signatures, hash-based schemes are the most suitable. While there’s no urgent quantum threat yet, the first step should be offering users a quantum-safe option. Once adopted, broader ecosystem migration can follow naturally.
Quantum Bitcoin Summit Recap: Preparing Bitcoin for the Quantum Era
Presidio Bitcoin hosted the Quantum Bitcoin Summit in mid-July, where researchers and developers explored quantum timelines, post-quantum cryptography, quantum threats to PoW, and how Bitcoin can prepare.
Widely Heard, Rarely Understood: User Profiles Behind Global Bitcoin Adoption
Cornell Bitcoin Club launched a research series on global Bitcoin adoption.
This survey across 25 countries found over 85% had heard of Bitcoin. However, only four (China, Switzerland, Hong Kong, Ukraine) had more than 20% of respondents aware of Bitcoin’s fixed 21 million supply. The takeaway: Bitcoin is widely known, but poorly understood—highlighting that it hasn’t yet reshaped how most people view money.
The report also explores Bitcoin ownership by gender, age, income, education, trust, and belief systems:
- Men are more likely than women to hold Bitcoin
- Most owners are aged 30–44, but in some countries, seniors (65+) and youth (18–29) dominate
- Lower-income groups have higher adoption rates
- People with less formal education are more likely adopters
- Those distrusting governments/financial institutions are more likely to own Bitcoin
- In developed economies, owners often work in the private sector; in emerging markets, many are self-employed, especially where traditional finance is inaccessible or untrusted
RGB v0.11.1 Launches: Create and Manage Digital Assets on Bitcoin and Lightning
RGB v0.11.1 enables anyone to create, transfer, and manage digital assets—including stablecoins, NFTs, and community tokens—directly on Bitcoin and Lightning. RGB uses client-side validation, anchoring assets to Bitcoin while keeping verification off-chain, enabling privacy and scalability without compromising trust.
Rootstock to Launch Union Bridge in Q4: A Trustless BTC-DeFi Bridge
Rootstock’s 2025 roadmap highlights the launch of Union Bridge—a trust-minimized, verifiable bridge built on BitVMX. It introduces a 1-of-n honest assumption model between Bitcoin and Rootstock, aiming to remove custodians from BTC-DeFi. Mainnet launch is planned for Q4.
IOHK: Bridging Cardano Smart Contracts to Bitcoin with RISC-V
IOHK outlines how it connects Cardano smart contracts to Bitcoin using:
- Untyped Plutus Core (UPLC) as a serialized smart contract format
- A CEK (Control, Environment, Continuation) interpreter architecture
- RISC-V, an open-source reduced instruction set architecture
The core component is BitVMX, an optimistic Bitcoin verifier that securely runs off-chain logic using RISC-V.
BitVM Alliance: Exploring an Open-Source Paradigm for Cryptographic Research
David Tse, co-founder of Babylon Protocol, discusses how the BitVM Alliance promotes open collaboration in Bitcoin innovation. Members share early ideas on Twitter/X to spark discussion—shifting from closed academic papers to open community development.