Code based cryptography and quantum attacks

Chuck Easttom

S. P. Kulik, S. N. Molotkov

Abstract We discuss the photon number splitting attack (PNS) in systems of quantum cryptography with phase coding. It is shown that this attack, as well as the structural equations for the PNS attack for phase encoding, differs physically from the analogous attack applied to the polarization coding. As far as we know, in practice, in all works to date processing of experimental data has been done for phase coding, but using formulas for polarization coding. This can lead to inadequate results for the length of the secret key. These calculations are important for the correct interpretation of the results, especially if it concerns the criterion of secrecy in quantum cryptography.

Peter P. Rohde

S. N. Molotkov

Abstract Quantum key distribution (QKD) systems are open systems. Thus, an eavesdropper can actively influence the elements of the system through the communication line, altering their regular operation. One known attack is an attack with detector blinding. With such an attack, the eavesdropper can obtain the entire key and remain undetectable. The paper proposes a fundamentally new method of detecting and protecting quantum cryptography systems with phase coding against the attack with avalanche detector blinding. The proposed method is based on diverting a part of the input signal in the receiving terminal to bypass the interferometer and deliver it to the same avalanche detectors. Measuring the detector response in different time windows, both for the bypassed signal and the normal operation range, one can effectively identify the ongoing detector blinding attack. The method does not require radical changes in existing quantum cryptography systems and is quite universal, since it can be used for any phase-coded quantum key distribution protocol. The method provides a fundamental strategy of detecting and protecting against the attack at the level of the quantum key distribution protocol, and not at the level of technical ‘patches’.

János A. Bergou, Mark S. Hillery, Mark E. Saffman

Pallavi Niraj Vithalkar

New developments in quantum computing have made people worry that current security methods could be broken by quantum attacks. Some mathematical problems are hard to solve, which is how traditional encryption methods like RSA and ECC keep their secrets safe. However, quantum computers might be able to solve these issues a lot faster than regular computers, which makes these methods less safe. Because of this threat, experts have been working hard to make post-quantum cryptography methods that quantum computers can't break. These methods are made to stand up to the strength of quantum algorithms and protect the privacy, integrity, and validity of private data even when quantum attackers are present. Lattice-based cryptography is a potential method for post-quantum encryption. Its security comes from the difficulty of certain lattice problems. Lattice-based methods are thought to be safe from threats from both traditional and quantum computers because they offer good security promises. Lattice-based cryptography is a flexible way to build different types of cryptographic primitives, like encryption, digital signatures, and key sharing protocols. The study of code-based cryptography, which is based on how hard it is to decode some error-correcting codes, is another important advance. Code-based methods have been around for a long time and have been studied a lot, which makes them a good choice for security after quantum computing. Code-based cryptography is also easy to use and has strong security features, which makes it a good choice for real-world situations. Multivariate polynomial cryptography is another possible choice for cryptography after quantum computing. The safety of this method depends on how hard it is to solve systems of multivariate polynomial problems. Multivariate polynomial methods might not be as secure as lattice-based or code-based cryptography, but they are interesting options for some situations and places with limited resources.