Bitcoin researchers have proposed a system for private transfers directly on the network without requiring a soft fork or changes to its consensus rules.

The Sept. 24 paper from [[alloc] init] researchers Clara Shikhelman, Mikhail Komarov, and Aleksei Moskvin introduces Shielded Bitcoin, a metaprotocol designed to conceal transaction amounts, senders, recipients, and links between transfers while publishing its protocol data through Bitcoin mainnet.

The design adapts techniques pioneered by Zcash, including encrypted notes, public nullifiers and zero-knowledge proofs, but does not introduce a separate blockchain. Bitcoin instead provides the publication and ordering layer from which participants reconstruct the private transaction state.

That would extend Bitcoin privacy beyond existing techniques such as CoinJoin, PayJoin and Silent Payments, which can complicate transaction tracing or reduce address reuse but leave amounts and other transaction details visible.

The proposal avoids waiting for a Bitcoin upgrade by moving the privacy logic above the network’s consensus rules.

Users would hold BTC-denominated value as encrypted notes. When funds are transferred, the sender would publish an envelope containing encrypted outputs, public nullifiers marking previously held notes as spent, and a zero-knowledge proof establishing ownership and value conservation.

The amount being transferred and the identities of the counterparties would remain hidden.

Bitcoin miners and nodes would not validate the shielded state themselves. Instead, implementations following the Shielded Bitcoin rules would scan BTC blocks and replay accepted transfer envelopes in their recorded order, producing a common note tree and spent-note set.

Bitcoin would therefore provide the timestamped transaction history and ordering needed to reconstruct the system, while the metaprotocol would handle encrypted balances and transfer verification.

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