Overview
- The Shielded Bitcoin whitepaper was published on Sept. 24, 2026 and proposes a metaprotocol that embeds encrypted transfer data on Bitcoin while keeping Bitcoin’s consensus rules unchanged.
- The design requires only a Bitcoin node plus an off-chain indexer to rebuild a private note state using public nullifiers and zero-knowledge proofs, which means miners and full nodes would not validate the privacy layer.
- The team 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 a key open item.
- The current prototype carries very large storage costs—reported at roughly 330 TB—while the researchers aim to reduce that footprint toward about 100 GB before a practical rollout.
- Entry and exit points still leak on-chain metadata such as timing, fees and transaction patterns, which raises limits on anonymity and leaves potential forensic and regulatory questions if the system is adopted.