International Association
for Cryptologic Research

With the advancement of quantum computers, it has been demonstrated that Shor's algorithm enables public key cryptographic attacks to be performed in polynomial time. In response, NIST conducted a Post-Quantum Cryptography Standardization competition. Additionally, due to the potential reduction in the complexity of symmetric key cryptographic attacks to square root with Grover's algorithm, it is increasingly challenging to consider symmetric key cryptography as secure. In order to establish secure post-quantum cryptographic systems, there is a need for quantum post-quantum security evaluations of cryptographic algorithms. Consequently, NIST is estimating the strength of post-quantum security, driving active research in quantum cryptographic analysis for the establishment of secure post-quantum cryptographic systems. In this regard, this paper presents a depth-optimized quantum circuit implementation for SEED, a symmetric key encryption algorithm included in the Korean Cryptographic Module Validation Program (KCMVP). Building upon our implementation, we conduct a thorough assessment of the post-quantum security for SEED. Our implementation for SEED represents the first quantum circuit implementation for this cipher.