Shielded Bitcoin: private payments on Bitcoin without a soft fork?

Every Bitcoin payment is public: anyone can see the amounts and follow coins from address to address. On 24 September 2026 the New York research lab [alloc] init published Shielded Bitcoin, a proposal for private transfers directly on Bitcoin, with no soft fork. Its founder, Misha Komarov, presents it at three conferences this autumn.

The design borrows from Zcash, a separate cryptocurrency known for private payments:

• Your bitcoin inside the system is held as an encrypted note. Only you can read it.
• When you spend it, the transaction publishes a zero-knowledge proof: a short piece of math that shows the payment follows the rules without revealing who paid whom or how much.
• All the data is written on Bitcoin. Bitcoin nodes do not check the private rules; separate software reads the data in block order and rebuilds the private balances. Any two correct programs get the same result.

The white paper says a shielded transfer hides the amount, sender, receiver and its place in the payment graph. Bitcoin itself does not change, and there is no separate blockchain, token or company in the middle.

• Getting in and out. The September paper covers transfers inside the system. How bitcoin moves into the pool and back out is left for a second paper.
• Experimental cryptography. That entry and exit relies on the team's PIPEs research and a technique called witness encryption. Komarov calls it "still pretty experimental". The lab said in September that it had cut the encrypted files the scheme needs to about 8 terabytes.

Adding privacy to Bitcoin's own rules would need a soft fork, and those are slow and hard to agree on, as the BIP-110 episode showed. Shielded Bitcoin tries to avoid that. Critics and supporters are now testing whether the assumptions hold. Komarov has urged Bitcoin users to give feedback now, saying that in about a year it would be too late to shape the design.

All three conferences are on our calendar and in Events.