Post-quantum stealth address protocols

The Stealth Address Protocol (SAP) allows users to receive assets through stealth addresses that are unlinkable to their stealth meta-addresses. The most widely used SAP, Dual-Key SAP (DKSAP), and the most performant SAP, Elliptic Curve Pairing Dual-Key SAP (ECPDKSAP), are based on elliptic curve cryptography, which is vulnerable to quantum attacks. These protocols depend on the elliptic curve discrete logarithm problem, which could be efficiently solved on a sufficiently powerful quantum computer using the Shor algorithm. In this paper, three novel post-quantum SAPs based on lattice-based cryptography are presented: LWE SAP, Ring-LWE SAP and Module-LWE SAP. Among them, the Module-LWE SAP, which is based on the Kyber key encapsulation mechanism and Dilithium signature scheme, achieves a 67% scan-time improvement over ECPDKSAP. In contrast to DKSAP and ECPDKSAP, the Module-LWE design achieves long-term quantum resistance through the hardness of Module-LWE and the post-quantum guarantees of Kyber and Dilithium. However, this improvement in scan time and the benefit of long-term post-quantum security come at the cost of substantially larger on-chain announcements and meta-addresses, resulting in a clear trade-off between computational efficiency, long-term security and storage cost.