The advent of quantum computing will transform the field of cryptography forever: Current cryptographic protocols rely on the hardness of number-theoretic problems, which can be efficiently solved by Shor's algorithm, rendering these encryption methods insecure.
The first post-quantum secure algorithms have been standardized. To further improve cryptoagility, National Institute of Standards and Technology (NIST) has recently initiated an additional standardization effort for post-quantum digital signatures. This chapter explores signature schemes based on coding theory, providing an overview of general design principles, specific schemes, and implementation aspects.
An alternative solution to the threat posed by quantum computers is Quantum Key Distribution (QKD), which leverages principles of quantum mechanics to provide secure key exchange. QKD allows two parties to exchange keys securely, with the assurance that any eavesdropping attempts can be detected, thereby addressing the key distribution problem inherent in classical cryptography. This chapter illustrates the potential of QKD and the challenges involved in its implementation.