Inside the 'Shielded Bitcoin' paper that proposes private BTC payments using Zcash tech

Mert Mumtaz, cofounder of Helius, which provides infrastructure for Solana developers, and a Zcash proponent, described the proposal on X as “a synthetic ledger with significant tradeoffs.”

He pointed to “a trusted setup” and “no fee anonymization,” meaning the Bitcoin wallet paying to publish a private transfer could still be visible. He also criticized the absence of a deposit and withdrawal mechanism, writing that there was “no in-protocol mechanism for getting actual BTC in or out (which means you are holding synthetics).”

“I respect that people are working on this and taking notes from zcash finally,” he wrote, adding that the proposal would require years of additional research and development.

Cypherpunk, a company that holds and mines Zcash, welcomed the research but did not perceive it as competition for the existing network. “Privacy works best when built into the base layer. Not requiring Bitcoin changing is this design's biggest selling point, and also its biggest drawback,” the company wrote.

“More privacy on Bitcoin is good for everyone,” the firm added.

Meanwhile, [alloc] init acknowledges several of those limits. Their reference design used in the paper requires a cryptographic setup whose security depends on at least one participant acting honestly. Transfer timing and fee payments remain visible, while an efficient way for lightweight wallets to verify the reconstructed payment history is listed as future work.