How are oil tankers using secret codes & crypto to pass through the Strait of Hormuz?

Iranian Navy is doing background checks on oil tankers passing through the Strait of Hormuz to make sure they have no US/Israel links, Bloomberg reported. Once cleared, ships are asked to pay a "toll", which has a starting price of $1/barrel, in Chinese yuan or cryptocurrency. They then get a secret permit code, which they broadcast while crossing the Strait.