Shielded Bitcoin proposes Zcash-style privacy on Bitcoin without a fork

Cryptography research firm Alloc Init published a paper on Shielded Bitcoin, a design for Zcash-style private transfers on Bitcoin's base layer without consensus changes. Recipients, amounts and the path between coins would sit in encrypted notes, but moving value in and out still relies on vaults enforced by an unfinished witness-encryption construction.

• No soft forks, no bridges, no operators — just Bitcoin
• Privacy comes from encrypted notes instead of the public UTXO graph
• On- and off-ramps depend on vaults using unfinished witness encryption
• Architecture is closer to Zcash than to Tornado Cash, not a mixer