Anonymous Post-Quantum Cryptocash (Full Version)

In this paper, we construct an anonymous and decentralized cryptocash system which is potentially secure against quantum computers. In order to achieve that, a linkable ring signature based on ideal lattices is proposed. The size of a signature in our scheme is O(logN), where N is the cardinality of the ring. The framework of our cryptocash system follows that of CryptoNote with some modifications. By adopting the short quantum-resistant linkable ring signature scheme, our system is anonymous and efficient. We also introduce how to generate the verifying and signing key pairs of the linkable ring signature temporarily. With these techniques, the privacy of users is protected, even though their transactions are recorded in the public ledger.