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A Benefit For All: Direct Public Involvement in Advanced Encryption Standards

When engineers and computer scientists design standardised digital communication and services such as encryption, which should guarantee security, privacy and authenticity of the messages, the intended users worldwide should have trust and confidence in these services. Transparency and public scrutiny of encryption methods are therefore crucial. Hence the evaluation of these services should not be limited to the small research community involved but should be open to all interested parties, including the general public.

The authors of today’s post, which forms part of a larger series of blogs that representatives of the LERU focus group on Public Engagement are writing to inspire and inform academics, societal partners and citizens who have a keen interest in Public Engagement, are Prof. dr ir Vincent Rijmen, and Prof. em. dr ir Joos Vandewalle, both from LERU University KU Leuven, Belgium.

Prof. em. dr ir Joos Vandewalle
Prof. dr ir Vincent Rijmen

While the theme of Public Engagement of research is often focused on Citizen Science, their post intends to widen the scope of public evaluation to research activities such as encryption, where outsiders like citizens, communities and institutions are critically involved.

A considerable amount of modern encryption is conducted through the Advanced Encryption Standard (AES), an open standard published by the US National Institute for Science and Technology (NIST).1 NIST is a US Government organization of the Department of Commerce that is working with industry and academia to enhance economic security and improve quality of life for regular citizens.

This post focuses on Vincent’s own work as one of the two designers of the Rijndael algorithm, which was selected in the AES competition, and that hence was standardized as AES. Vincent and Joos describe the process of setting up an open standard for encryption of digital messages and the engagement of the public, they argue that the engagement of the public in encryption standards has significant societal value.

The History of Encryption and Public Engagement

Historically, the field of encryption, data security and cryptography has been the playground of secretive government services and spies. For a long time, it was an area of closed science by definition. The widespread use of the computer, internet and smartphone and the increased reliance on digitally stored data resulted in an increased interest in cryptography, as well as its uses for civilian purposes. Today, if you commute using public transport, while drinking a coffee that you paid for with your credit card and read the daily news on your smartphone, then you have used encryption at least three times before you even reach your office.

It was commonly felt in the 1990s that progress in computing power over the past decades had made the then-commonly used Data Encryption Standard (DES) obsolete and vulnerable to attack. At this point, NIST initiated the development process of a new standard, making it a fully open process from the very start.

NIST launched an open competition for encryption algorithms, declaring that all submitted algorithms and their evaluations would be fully open to the public. NIST representatives travelled around the world to solicit submission from research groups in academia, and industry, and even the wider public. They organized open workshops and conferences to engage academics and the public.

This was the moment Vincent and his colleague, Dr Joan Daemen, as young postdoc researchers in cryptography at KU Leuven, joined forces to submit a proposal. After a five-year standardization process, in which fifteen competing designs were presented and publicly evaluated, the Rijndael cipher of Vincent and Joan was selected in 2001 as the most suitable. Among the quoted reasons were the mathematical elegance of the design, which allowed more easy verification of its security, and its high speed on a variety of computing platforms (high-end servers, ordinary desktop computers, smartcards, embedded devices).

Public Engagement as a Research Strength

Two important reasons to opt for a fully open process were the following. Firstly, making every detail of the design and the evaluation process public, increased public confidence in the standard. A closed design would typically suffer from the suspicion that it might include hidden backdoors, such as deliberately inserted weaknesses, allowing organizations in the know to break the security.

Secondly, they relied on public scrutiny to eliminate accidental weaknesses. Were a serious weakness in a worldwide standard to be discovered, this would force the quick installation of new algorithms and software in billions of smartphones and computers, thereby creating headline news. This undesired possibility motivated many researchers to study the security of the standard and to publish their findings in the hope to become famous overnight.2

Cryptography is excellently suited to Public Engagement and Citizen Science because it has a characteristic or distinctive property, which is that, within the field, researchers are developing methods that should act against methods developed by other researchers. This is quite rare in science. While science and technology in general can be seen as a means for humankind to outwit nature – for example where we build houses to keep out the cold or the heat – cryptography is more a matter of humans trying to outwit other humans. Cryptographers do not face the impartial laws of physics: instead, they face their fellow cryptographers, as well as cybercriminals.

It is essentially a process of measure and countermeasure, where one party tries to imagine all the possible ways by which another party will try to evade defensive measures. However, history has shown time and again that designers of encryption methods are too optimistic about the efficacy of their work. Cryptographers working in closed circles need to be constantly on guard to avoid making this mistake. In comparison, cryptographers working in the open world automatically receive input from outsiders, who will study their work from different angles and quickly reveal shortcomings.

The AES development process was a Public Engagement/Citizen Science success story. During the whole process there were inputs made by academics, by researchers from industry, and by interested individuals. All inputs were bundled and addressed in public reports written by NIST employees.

The costs and benefits of Public Engagement/Citizen Science

However, Public Engagement/Citizen Science also has a cost for the designers. It takes effort to process and evaluate citizens’ contributions. Typically, these efforts are duplicated to a larger degree than would be the case when all research is planned centrally and executed in a few labs. Professional researchers, who are not used to sharing their research with people outside their scientific community, also need to develop their communication skills. Sometimes researchers can believe Public Engagement is a waste of time.

Moreover, in the case of AES, openness implies that it is freely available for anyone to use. The algorithm is available for free to everyone, and the researchers and citizens who invented it and continue to evaluate it for weaknesses do not receive any direct financial compensation for their efforts. Although free and public availability was an explicit requirement of NIST, this is an aspect that could lead to many incredulous remarks including poor commercial interest, weak valorization efforts – in other words, failing to recognise the value or an algorithm – or even naivety on the part of the designers.

However, many researchers and citizens are not primarily driven by the desire to make money. Instead, they dream about making a positive impact on their society, and contributing to new or better products or services that are used to improve the lives of other people: being recognized for this activity is already a very satisfactory experience. Making significant contributions to open science has many benefits for the designers. The fact that one has a proven record of achievement leads to better positions on the job market, opportunities to participate in other interesting projects, and more chances to meet people in related fields. An added benefit of the public nature of the algorithm is that anybody in the world can implement it in the systems that they design. This is a key reason for the widespread use of AES in billions of devices and services like the end-to-end encryption of WhatsApp, wherein citizens contributed by checking the speeds and security of the competing methods on various competing platforms,

Finally, we would recommend that every researcher seize any opportunities for participation in open competitions and open standards that invite Public Engagement. Even if your contribution is ultimately not selected, a competition is a unique opportunity to collaborate with people having very different backgrounds and points of view. Such interaction often results in valuable feedback and is always refreshing.

Contributors
Vincent Rijmen, is Professor at KU Leuven, Belgium, and with Joan Daemen he is the designer of the Rijndael algorithm, that was selected in the AES competition. He studies mathematical theories for the design of symmetric cryptography primitives, the design and cryptanalysis of primitives for symmetric cryptography: block ciphers, hash functions, MACs, stream ciphers. A driving force is the formalization of both the design and the practice of cryptanalysis by introducing slightly more advanced concepts from mathematics. He is currently heading an active research group in the COSIC division of KU Leuven.

Joos Vandewalle, is Professor emeritus at KU Leuven, and a former President of the Royal Flemish Academy of Belgium for Sciences and the Arts, KVAB. He supervised 43 PhD students (the two designers of the Rijndael algorithm among them) and performed research in mathematical engineering and design of algorithms for signal processing, data science and cryptography.

1 NIST estimates the economic benefit of the AES at $250 Billion.

2 Here you can read an example of a newstory offering such an outcome:


OpenEdition suggests that you cite this post as follows:
joosvandewalle (March 26, 2025). A Benefit For All: Direct Public Involvement in Advanced Encryption Standards. LERU Public Engagement Scholarly Blog. Retrieved May 15, 2026 from https://lerupesb.hypotheses.org/260


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