Post-quantum cryptography is crucial because of the growing threat that quantum computing poses to classical cryptographic schemes including RSA and ECC. In particular, such schemes rely on mathematical problems that quantum algorithms, such as Shor’s algorithm, can solve efficiently. To address the issue, we present an Enhanced Lattice-Based Fiat-Shamir Protocol making use of the Ring Learning With Errors (RLWE) problem for secure authentication. We add an automorphism-based security enhancement to increase resilience against algebraic attacks. We prove the correctness, efficiency, and security of the protocol via various computational experiments, which showcase the potential to offer post-quantum secure authentication against practical overhead.