Post-Quantum Cryptography Key Expansion Method and Anonymous Certificate Scheme Based on NTRU

Abstract: NTRU is one of the important lattice-based post-quantum cryptography methods, offering resistance against quantum computing attacks. However, a drawback of NTRU lies in its relatively low efficiency in generating key pairs. Therefore, this study proposes an NTRU-based key expansion method that enables efficient public key expansion. Furthermore, the proposed method is applied to an anonymous certificate scheme, allowing an end entity to generate a key pair only once, after which the certificate authority can expand multiple distinct public keys for anonymity. The experimental results demonstrate that the proposed key expansion method achieves significantly higher efficiency than key pair generation.