Shielded Bitcoin: Researchers Propose Private Transfers Without Soft Fork

Researchers have proposed a new approach to bring Zcash-style private Bitcoin transfers without requiring a soft fork of the base protocol. The proposal, titled Shielded Bitcoin, aims to hide transaction amounts, senders, receivers, and linkages to previously spent funds by relying on encrypted 'notes' and zero-knowledge proofs.

The design mirrors core Zcash components, using encrypted notes, nullifiers to prevent double-spending, and zero-knowledge proofs for transaction validity. However, Shielded Bitcoin differs from Zcash in that it is not presented as a separate shielded blockchain with its own consensus mechanism.

Instead, it aims to plug a Zcash-like privacy system into Bitcoin's existing infrastructure, using encrypted transaction artifacts and proof verification performed by external components. The researchers acknowledge that large deposits do not automatically translate into a large anonymity set, which could limit the effectiveness of the system in early stages.