Optimized Quantum Implementation of SEED

With the advancement of quantum computers, it has been demonstrated that Grover’s algorithm enables a potential reduction in the complexity of symmetric key cryptographic attacks to the square root. This raises increasing challenges in considering 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.