A Diagrammatic Approach to Information Flow in Encrypted Communication

Björn Tackmann

Peter Hines

We give diagrammatic tools to reason about information flow within encrypted communication. In particular, we are interested in deducing where information flow (communication or otherwise) has taken place, and fully accounting for all possible paths. The core mathematical concept is using a single categorical diagram to model the underlying mathematics, the epistemic knowledge of the participants, and (implicitly) the potential or actual communication between participants. A key part of this is a `correctness' or `consistency' criterion that ensures we accurately & fully account for the distinct routes by which information may come to be known (i.e. communication and / or calculation). We demonstrate how this formalism may be applied to answer questions about communication scenarios where we have the partial information about the participants and their interactions. Similarly, we show how to analyse the consequences of changes to protocols or communications, and to enumerate the distinct orders in which events may have occurred. We use various forms of Diffie-Hellman key exchange as an illustration of these techniques. However, they are entirely general; we illustrate in an appendix how other protocols from non-commutative cryptography may be analysed in the same manner.

Steve Cordell

Kiran Adhikari, Christian Deppe

Large-scale quantum networks, known as quantum internet, hold great promises for advanced distributed quantum computing and long-distance quantum communication. It is essential to have a proper theoretical analysis of the quantum network and explore new applications and protocols that justify building such an extensive network. We propose a novel diagrammatic way of visualizing information flow dynamics within the quantum network, which preserves the causal relationship between different events at different nodes. This facilitates synchronization among network nodes, studies the error propagation, and allows for tracking valuable quantum resources. Additionally, We propose a quantum information scrambling protocol, where a specific node scrambles secret quantum information across the entire network. This protocol ensures that a malicious party would need access to a significant subset of the network to retrieve the information.

V. A. Maharramov, Tofiq Mansurov

The development of experimental quantum physics in recent years has led to the fact that the abstract ideas of quantum mechanics began to find practical application for the protection of information in a rapidly developing field such as fiber-optic communication lines (FOCL). On the basis of (smart) translucent SMART mirrors, optical splitters, switches, schemes of unidirectional, counter, bidirectional and universal multiplexers and demultiplexers, and the principle of distributing quantum encryption keys between authorized users have been developed. It is shown that it is possible to improve the speed of the process of switching and multiplexing of information flows in comparison with traditional mechanical switches. The paper proposes a circuit solution for an all-optical network (All-Optical Networks – AON) with the possibility of generating and distributing quantum encryption keys between authorized users. The aim of this work is to develop a principle for constructing quantum systems for the secure distribution of encryption keys on all-optical networks between selected (4 or more) users, as well as methods for generating, transmitting and receiving these keys in real time. In this regard, there is a need to develop a switch and a multiplexer of information flows.

Yi-Ting Chiang, Tsan‐sheng Hsu, Churn‐Jung Liau +4 more