Shielded Bitcoin: A Private Payments Proposal for the Main Chain

A team of researchers from [[alloc] init], a New York cryptography lab, has proposed a plan to bring private transactions to Bitcoin without changing its core rules. The plan, known as Shielded Bitcoin, is designed to hide transaction amounts and counterparties while keeping the value stored in encrypted records called 'notes.' This approach is inspired by Zcash's 'shielded' payments but does not require any changes to Bitcoin's base code.

The researchers claim that their design can provide strong privacy guarantees without sacrificing transparency. Each user would have separate viewing keys, allowing them to share specific transactions with others while keeping the rest of their data private. This feature is particularly relevant in today's regulatory environment, where companies are under pressure to comply with anti-money laundering and know-your-customer laws.

However, there are several challenges that need to be addressed before Shielded Bitcoin can become a reality. The team has identified three main catches: the lack of an entry-and-exit mechanism for users to move their funds in and out of the private system, the increased block space required for shielded transfers, and the reliance on a one-time trusted setup ceremony.

While some experts have expressed enthusiasm for the proposal, others have raised concerns about its feasibility. Helius cofounder Mert Mumtaz, a vocal Zcash supporter, called it 'a synthetic ledger with significant tradeoffs' that would require 'years of additional research.'