Overview
- The Shielded Bitcoin whitepaper was published Sept. 24 and lays out a metaprotocol that embeds encrypted notes, public nullifiers, and zero-knowledge proofs in Bitcoin transactions.
- Instead of changing Bitcoin rules, the system would publish privacy data on-chain while independent indexers rebuild a private note state and check nullifier-based spends.
- The proposal plans to use PIPEs v2 witness-encryption to enable trustless peg-in and peg-out flows, but the detailed peg construction has not yet been published and remains unfinished.
- Early implementation estimates show major obstacles: a prototype requires roughly 330 terabytes of storage with a target near 100 gigabytes, and entry/exit on-chain metadata and light-client verification could still leak links.
- If the missing peg and scaling work are solved, analysts say Shielded Bitcoin could reduce the need to use separate privacy networks like Zcash and raise new questions for regulators and blockchain forensics.