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  • Writer's pictureDavid Mitlyng

Weekly Takeaways-June 2, 2023

Updated: Jun 19

Theme of the Week

The Need for Secure Time We all have a general idea about what it means to be secure. If you boil it down, security relies on meeting three key elements: confidentiality, integrity, and availability. Securing data is the focus of a multi-trillion dollar cybersecurity industry and the push towards a zero trust architecture. But what about securing time? Considering that all networks, financial transactions, and power grids need a common time reference, and a widespread disruption of that time source would be catastrophic. Confidentiality isn’t a concern; after all, you want everyone to know the time. But availability – having access to that time reference – and integrity - being assured the time is correct – are very important. For most commercial users, this time reference is sourced via satellite through RF signals that can be easily jammed (removing integrity) and spoofed (removing authentication). Fortunately, authentication concerns can be addressed through quantum communications. Quantum communication systems that manipulate the quantum properties of photons were developed for the secure distribution of encryption keys, known as quantum key distribution (QKD). The hardware and some of the underlining security protocols developed for QKD can also be applied for secure time distribution, effectively creating a trusted and authenticated time reference (see below). This opens the door to a whole new paradigm for a future secure time network. Last Week's Theme: Security vs. Resilience, and Why You Need Both

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The More You Know...

Secure Time through Quantum Communications Time distribution networks rely on “transferring reference clock synchronization from one point to another, often over long distances.” Over global distances this is achieved via RF signals from a global navigation satellite systems like GPS (check out this site for a good explanation of how these systems work). The satellite clock provides the time reference that is sent to the receiver via a RF signal. This signal contains a pseudorandom code (sequence of ones and zeros) that is also known by the receiver. The offset between the satellite code and the receiver code is then used to calculate the difference between the receiver and satellite clocks (or, conversely, the distance between the receiver and satellite using the speed of light).

Calculating the distance between Satellites and Receivers. Credit: Department of Geography, The Pennsylvania State University
Calculating the distance between Satellites and Receivers. Credit: Department of Geography, The Pennsylvania State University

The problem: this RF one-way time transfer design is fundamentally insecure.

An adversary that wants to spoof the signal has two methods at their disposal:

  1. If they know the pseudorandom code, they can create their own signal.

  2. They intercept the original signal and modify it or re-transmit it with time delay.

But time transfer with entangled photons eliminates these security loopholes:

  1. By replacing the pseudorandom code with random entangled photons, thereby eliminating the possibility that an adversary would be able to create their own signal.

  2. By eliminating the ability to measure and re-transmit the quantum signal due to the no-cloning theorem.

This eliminates concerns about the authentication of the time reference. The integrity of the time reference is addressed by building a resilient network.

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