Alloc Init launches 'Shielded Bitcoin' privacy proposal, no soft fork required

According to Woofun AI, the crypto research team Alloc Init has officially launched a "Shielded Bitcoin" proposal aimed at enabling privacy-preserving transactions—similar to Zcash—on the Bitcoin network without triggering a soft fork. The initiative seeks to restructure transaction privacy through technical means while preserving the underlying consensus mechanism of the base protocol. It offers a new pathway for Bitcoin users, long constrained by the blockchain's transparent ledger, to balance compliance and privacy. The effort marks the latest attempt to apply zero-knowledge proof technology in a sidechain-like context on a major public blockchain.

Technical Blueprint Released

Clara Hickelmann, Mikhail Komarov, and Alexei Moskvin jointly released the technical blueprint on Thursday. The core architecture departs from the traditional approach of having miners execute privacy protocols. Instead, it treats Bitcoin as a neutral publication and ordering layer. Under this framework, specialized indexer software assumes critical responsibilities: verifying zero-knowledge proofs, confirming that funds have not been double-spent, and reconstructing the privacy system's state.

Design Inspired by Zcash

Data compiled by Woofun AI indicates that the design draws heavily from Zcash's logic, incorporating:

• Encrypted notes
• Public nullification mechanisms to mark notes as spent
• Zero-knowledge proofs to ensure transaction validity

Notably, "Shielded Bitcoin" does not create an independent blockchain or consensus mechanism. Instead, it relies entirely on existing infrastructure for state synchronization and verification.

Privacy Concerns: The User Base Problem

The effectiveness of privacy protection is closely tied to the size of the user base—a structural weakness that has drawn sharp scrutiny from industry experts.

Developer Vadim Zavodir noted on X (formerly Twitter) that privacy depends on the size of the user group. Zcash took years to build an effective anonymity set, while a new system starting from scratch could initially face a situation where the anonymity set consists of just one person.

The researchers themselves acknowledged in supporting documentation that large deposits do not automatically translate into high anonymity. If a small number of users dominate the creation of encrypted notes, or if specific wallets exhibit unusual behavioral patterns, observers can still trace transaction links through on-chain analysis.

Security Criticism and Support

On the security front, Pierre-Luc Dalair-Demers, founder of Pauli Group, offered sharp criticism, arguing that the proposal lacks quantum resistance entirely. While he is exploring an alternative version based on post-quantum signature schemes, the current architecture remains highly vulnerable in the face of quantum computing threats.

In contrast, Eli Ben-Sasson, co-founder of Zerocash and CEO of StarkWare, expressed support. He noted that the original Zerocash paper was intended to bring privacy to Bitcoin. Although he has not yet read the new paper in detail, he looks forward to seeing the vision of achieving privacy and scalability through zero-knowledge proofs become a reality.