The Shielded Bitcoin privacy paper was published by Clara Shikhelman, Mikhail Komarov, and Aleksei Moskvin of the cryptography firm alloc. The paper proposes enabling private Bitcoin payments by adapting Zcash technology to hold bitcoin-denominated value as encrypted notes. The proposal describes transfers that use those encrypted notes to represent and move value while keeping amounts and the identities of senders and recipients private.
The Shielded Bitcoin design represents bitcoin-denominated value as encrypted notes that hold value while concealing transactional details. When an encrypted note is spent, the system publishes a marker and a mathematical proof that demonstrate the sender owned the referenced funds and had not created new ones. Those published proofs and markers serve to show ownership and the absence of illicit creation without revealing the transferred amount or the identities of the sender and recipient. The mechanism thus separates public verification of ownership and supply integrity from the confidentiality of amounts and counterparties, with the encrypted notes preserving privacy for the transaction details.
Zcash shielded pools held about 4.9 million ZEC on Friday, an amount that was up 14% from July 30. That total represented roughly 29% of issued coins. The held ZEC were reported as worth about $7.8 billion. These pool figures are presented in the context of activity covering late July through early September.
Zcash recorded roughly 63,000 shielded transactions last week. That weekly count was its busiest week for private transfers since 2022 and the fourth-highest on record. Across Zcash’s network, reported transfer volume exceeded $23 billion for the same week. That weekly transfer total was reported as the largest since 2021 and the second-highest in the network’s history.
The summarized figures focus on shielded-pool holdings, the share of issued coins held there, weekly shielded transaction counts, and total reported weekly transfer value. All figures reflect the reported activity from late July through early September.
The Zerocoin privacy concept was proposed in 2013 as a privacy extension to Bitcoin. Subsequent research under the Zerocash name developed those ideas further. That Zerocash research evolved into the Zcash project, which launched as a separate cryptocurrency in 2016. Since its launch, Zcash lets users choose between transparent payments and shielded payments, offering an option to execute transactions that conceal amounts and counterparties or to use conventional transparent transfers. Together, these published milestones trace a line from the 2013 Zerocoin proposal, through Zerocash research, to the 2016 launch of Zcash and to the network feature that provides selectable transparent or shielded payment modes.
The Shielded Bitcoin paper’s summary notes the concept currently lacks a finished way to lock up real BTC and release it again. The proposal would publish transfer data on Bitcoin while leaving verification checks to separate software that anyone could run. That approach places the transfer-recording on Bitcoin and offloads the privacy-related checks to external programs. The paper notes this arrangement could potentially allow a transaction to be confirmed even if the private payment failed Shielded Bitcoin’s checks.
These considerations appear in the paper’s summary. They are described there as current limitations of the concept.
