Pre-Quantum to Post-Quantum Cryptography: An Extensive Survey

The word “cryptology” was introduced by the ancient Greeks between 900 BC and 500 BC. The two primary branches of cryptology science are cryptanalysis and cryptography. Key-based cryptography, which is lately named "pre-quantum cryptography," is classified based on the number of keys used into three main categories of cryptography: symmetric key cryptography, asymmetric key cryptography and hash functions. This survey paper aims to give an overview of cryptography-related subjects. Descriptive and analytical methods are used in this extensive survey. Pre-quantum cryptography categories, including symmetric key cryptography, asymmetric key cryptography and hash functions, with detailed explanations and a comparison between the first two types. Symmetric key cryptography classification into block cipher and stream cipher, the difference between them, the essential types of stream ciphers, a comparative analysis between these types, the main structures of block ciphers, their design principles in detail and the differences between block cipher encryption algorithms are explained. Asymmetric key cryptography principles, basics and comparison of asymmetric key cryptography algorithms, in addition to the primary differences between symmetric and asymmetric key cryptography, are discussed. However, since the rapid increase in computer processing capabilities and the rise of quantum computers that can solve complicated problems that classical computers (CC) or supercomputers cannot solve in a feasible time, pre-quantum cryptography algorithms like the Advanced Encryption Standard (AES), Ron Rivest, Adi Shamir and Leonard Adleman (RSA) encryption algorithms that are used to interface with current communications protocols and networks are susceptible to attacks from quantum computers. Thus, in the era of quantum computing, pre-quantum cryptography security might be jeopardized. Therefore, post-quantum cryptography (PQC) that is strong against quantum computers has been explored. Accordingly, the recent trend of PQC algorithms, the differences among the varieties of their theoretical techniques and the selected standard mechanisms by the National Institute of Standards and Technology (NIST) are briefly expounded.