Threats Posed by Quantum Computers to State-of-the-Art Encryption Schemes

William Johnston Buchanan, Alan Woodward

The emergence of practical quantum computers poses a significant threat to the most popular public key cryptographic schemes in current use. While we know that the well-understood algorithms for factoring large composites and solving the discrete logarithm problem run at best in superpolynomial time on conventional computers, new, less well understood algorithms run in polynomial time on certain quantum computer architectures. Many appear to be heralding this next step in computing as ‘the end of public key encryption’. We argue that this is not the case and that there are many fields of mathematics that can be used for creating ‘quantum resistant’ cryptographic schemes. We present a high-level review of the threat posed by quantum computers, using RSA and Shor’s algorithm as an example but we explain why we feel that the range of quantum algorithms that pose a threat to public key encryption schemes is likely to be limited in future. We discuss some of the other schemes that we believe could form the basis for public key encryption schemes, some of which could enter widespread use in the very near future, and indicate why some are more likely to be adopted.

Sandeep Dommari

Zhixin Liu, Qiaoling Xie, Yongfu Zha +1 more

Abstract Asymmetric encryption has some important applications in the field of communication. In classical computers, most public key encryption schemes are designed based on computational assumption. In other words, they can ensure computational security. When the computing power is large enough, it will pose a threat to these encryption schemes. We propose a quantum public key encryption scheme which based on properties of quantum physics. Our scheme realizes encryption and decryption with few resources and does not rely on any computational assumption. The key in our scheme consists of classical bits and qubits. Where the private key are classical bit and public key are qubits. The public key are generated through private key. We analyze the performance and security of the scheme. Our scheme ensures the information-theoretic secure and can be implemented easily.

Gorjan Alagic, Anne Broadbent, Bill Fefferman +3 more

Zach Kirsch, Ming Chow

Jack Loughridge, Charuka Herath, Yogachandran Rahulamathavan +5 more

The advent of quantum computing poses a significant threat to traditional cryptographic algorithms, including RSA, Diffie-Hellman, and Elliptic Curve Cryptography, due to the capabilities of quantum algorithms like Shor’s algorithm. Post-quantum cryptography (PQC) has emerged to address these challenges, with lattice-based cryptography (LBC) being a prominent candidate. LBC, underpinned by hard mathematical problems like Learning with Errors (LWE) and Ring-LWE (RLWE), offers robust security against quantum and classical adversaries. In parallel, Ciphertext-Policy Attribute-Based Encryption (CPABE) has become a critical tool for enabling fine-grained access control in data-sharing scenarios, such as secure cloud storage and IoT. While existing CP-ABE implementations rely on bilinear pairings vulnerable to quantum attacks, lattice-based CPABE schemes provide a quantum-resistant alternative. Despite their potential, these schemes face challenges in computational efficiency, collusion resistance, and implementation correctness. Our contributions include a detailed mathematical breakdown of one of the state-of-the-art (SOTA) lattice-based CP-ABE schemes and a novel correctness proof for the same scheme.