Researchers from Alloc Init have introduced a novel system called Shielded Bitcoin, which seeks to enable private transactions on the Bitcoin network similar to those in Zcash, but without requiring a soft fork. This proposal utilizes zero-knowledge proofs and encrypted notes to obscure transaction details such as amounts, senders, and receivers.
By leveraging Bitcoin as a "neutral publication and ordering layer," Shielded Bitcoin aims to enhance user privacy without altering the core consensus of the Bitcoin protocol. The proposal suggests that separate software, known as indexers, would validate zero-knowledge proofs and ensure that funds are not double-spent.
Despite its innovative approach, the proposal has received mixed feedback. Developer Vadim Zavodil expressed skepticism, noting that a new privacy system would lack the established anonymity set that Zcash has built over time. He emphasized that the effectiveness of privacy relies heavily on user participation.
Concerns regarding quantum resistance were also raised by Pierre-Luc Dallaire-Demers, who highlighted that the current design is not equipped to withstand potential quantum computing threats. In contrast, Eli Ben-Sasson, co-author of the Zerocash paper, expressed optimism about the proposal's potential for enhancing privacy and scalability on Bitcoin's base layer.