A paper proposes private bitcoin payments with Zcash technology without changing the network's rules
The 56-page specification by Clara Shikhelman, Mikhail Komarov and Aleksei Moskvin of the firm [alloc] init still has no way to deposit real BTC or withdraw it, per CoinDesk.
Bitcoin-denominated value would be held in encrypted records called "notes". Bitcoin would store the data but not verify it: that job falls to separate software. A private transfer would take about 700 virtual bytes, versus 100 to 200 for an ordinary transaction, with fees roughly 4 times higher at the same rate, per CoinDesk.
There is no launch date, and the system relies on a trusted cryptographic setup. Mert Mumtaz described it as "a synthetic ledger with significant tradeoffs", per CoinDesk.
Sources: CoinDesk