Composable security of quantum position-based cryptography (25rit933)

The Banff International Research Station will host the "Composable security of quantum position-based cryptography" workshop in Banff from August 10 to August 24, 2025.

Imagine that you are sitting in front of your computer and are about to enter your account information into your bank's website, because you need to transfer money to your sibling who lives abroad. Suddenly, you start to worry: is this website really genuine? After all, scammers can fake the appearance of a website. If you could somehow ensure that the server with which you are interacting is located in the basement of your bank's local branch, you could rest assured, since it is very difficult to enter the bank's server room without permission. This illustrates the idea behind position-based cryptography: using the position of a party as a credential instead of, e.g., a secret key. The key building block for this novel kind of cryptography is secure position verification.

Unfortunately, secure position verification is impossible using ordinary computers. However, with quantum technologies, the situation changes---quantum information, unlike classical information, cannot be copied. This fact allows us to find protocols for secure position verification and, as a result, quantum position verification has recently attracted a lot of interest from researchers in quantum information theory. For position-based cryptography to be useful, however, we need to make sure that position-verification protocols stay secure if they are integrated into more complex communication protocols. Therefore, in our project we will develop a mathematical framework for proving composable security of such protocols, which will bring us one step closer to making quantum position-based cryptography a reality.

The Banff International Research Station for Mathematical Innovation and Discovery (BIRS) is a collaborative Canada-US-Mexico venture that provides an environment for creative interaction as well as the exchange of ideas, knowledge, and methods within the Mathematical Sciences, with related disciplines and with industry. The research station is located at The Banff Centre in Alberta and is supported by Canada's Natural Science and Engineering Research Council (NSERC), the U.S. National Science Foundation (NSF), and Alberta's Advanced Education and Technology.