A Review of Block Ciphers and Its Post-Quantum Considerations

Abstract

Recent advances in cryptography aim to address threats posed by quantum computers. However, these advances have focused disproportionately on asymmetric schemes, while symmetric primitives like block ciphers have received less attention. The common assumption is that doubling block cipher key sizes provides adequate quantum resistance, but this oversimplifies the challenge. This paper provides a systematic examination of block cipher security in the quantum computing era. The paper first establishes a formal framework for understanding block cipher security, covering their mathematical foundations and essential security properties. Building on this foundation, we examine how quantum computing fundamentally challenges these security assumptions, going beyond the simple impact on key lengths. Our review of recent research reveals that quantum attacks can exploit structural vulnerabilities in block ciphers and their modes of operation, requiring more comprehensive defenses than key length adjustments alone. We analyze emerging approaches in quantum-resistant design and identify critical areas requiring further research to ensure block cipher security in a post-quantum world.

Keywords

• Symmetric encryption
• block ciphers
• key size
• advanced encryption standard (AES)
• operation mode
• Feistel networks