The Complex Path to Quantum Resistance

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The Complex Path to Quantum Resistance
Communications of the ACM, September 2021, Vol. 64 No. 9, Pages 46-53
By Atefeh Mashatan, Douglas Heintzman

“As quantum computers are developed at a rapid pace, and with early models already on the market, the overall perception of the ICT community toward a quantum reality is slowly changing.”


There is a new technology on the horizon that will forever change the information security and privacy industry landscape. Quantum computing, together with quantum communication, will have many beneficial applications but will also be capable of breaking many of today’s most popular cryptographic techniques that help ensure data protection—in particular, confidentiality and integrity of sensitive information. These techniques are ubiquitously embedded in today’s digital fabric and implemented by many industries such as finance, health care, utilities, and the broader information communication technology (ICT) community. It is therefore imperative for ICT executives to prepare for the transition from quantum-vulnerable to quantum-resistant technologies.


This transition will be particularly complex, time-consuming, and expensive for larger organizations with vendor dependencies and/or legacy infrastructure. Hence, it is critical that ICT leaders spend adequate time—now, while they have the luxury to do so—on planning the transition and determining their next steps. Otherwise, they may find their organizations in a chaotic state, scrambling to meet a compliance deadline or to prevent an actual loss of confidentiality or integrity of their, their customer’s, or their partner’s sensitive information. The absence of a well-thought-out plan could result in further delays and security vulnerabilities. Ultimately, it could have drastic implications for their core businesses and bottom lines.


The good news is that security systems not susceptible to quantum attacks (that is, those that are quantum-resistant), can be implemented using today’s classical computers. Organizations will not need quantum computers to resist attacks by another party’s quantum computer. Several algorithms that are mathematically shown to be quantum-resistant already exist.


Standardization bodies such as the National Institute of Standards and Technology (NIST) in the U.S. and the European Telecommunications Standards Institute (ETSI) in Europe have been working on the standardization of quantum-resistant primitives since 2015, promising a final set of alternatives by 2025. In many cases, however, these algorithms may not be compatible with current hardware or software. For example, when existing algorithms are hardcoded in a piece of hardware, replacing the quantum-vulnerable algorithm with a quantum-resistant alternative involves swapping out the hardware.


Given the serious nature of the threat, the question organizations should be asking is how can the process of transitioning to quantum-resistant systems be accomplished in a timely and cost-effective manner, even as the solutions have yet to be standardized?


The industry’s challenge is in migrating to compatible hardware platforms and ensuring the software running on those platforms is upgraded to use quantum-resistant protocols. Depending on the needs of an organization and its approach to cryptography management, modifications to digital information security systems can range from relatively straightforward, quick, and inexpensive; to massively complex, drawn-out, and costly. The transition to a quantum-resistant state is no exception.


Competing quantum-resistant proposals are currently going through academic due diligence and scrutiny by industry leaders. Until the newly minted quantum-resistant standards are finalized, ICT leaders should do their best to plan for a smooth transition. This article provides a series of recommendations for these decision-makers, including what they need to know and do today. It will help them in devising an effective quantum transition plan with a holistic lens that considers the affected assets in people, process, and technology. To do so, the decision-makers first must comprehend the nature of quantum computing in order to grasp the impact of the impending quantum threat and appreciate its magnitude.


Threat to Cybersecurity

Quantum computing’s main potential threat to information security is in cryptography. Cryptography runs behind the scenes, out of the user’s view, to keep information and communications secure. Two broad types of cryptography exist: symmetric/secret key and asymmetric/public key. Understanding the difference between the two is critical, as quantum computing impacts each differently.



When planning a response strategy, security professionals need to be concerned about two forms of attacks: real time and harvest-then-decrypt.


Real-time attacks occur when a quantum computer is in the hands of an adversary. As mentioned, asymmetric cryptography relying on IFP or DLP is catastrophically vulnerable to a scalable quantum computer attack. Symmetric cryptography is vulnerable, at least with its current key sizes, for slightly different reasons. Organizations or individuals whose communications, transactions, and authentications are still using current asymmetric or symmetric algorithms could be attacked when a scalable quantum computer is realized.12 These real-time attacks are not currently possible, because a scaled-quantum computer is not yet available.


The harvest-then-decrypt attack happens when an adversary captures and stores encrypted data and sits on it until a quantum computer becomes available to provide a means for decryption. Depending on the sensitivity or the shelf life of the data, this type of attack can be a serious current threat. Malicious actors could harvest encrypted data today, put it aside for a few years, and wait for the availability of an affordable quantum computer so they can decrypt that data. Considering the many well-publicized large-scale security breaches of companies such as Yahoo in 2013 and 2014, Marriott Starwood Hotels in 2018, and Capital One in 2019, this threat is very real. (Note that in 2019 alone, four billion records were breached.) In the meantime, a constant game of cat and mouse is being played out between the attackers who seek to cause harm and the security professionals who are tasked with stopping them.


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About the Authors:

Atefeh Mashatan is an associate professor at the Ted Rogers School of Information Technology Management and the founder and director of the Cybersecurity Research Lab at Ryerson University. Mashatan’s expertise at the frontlines of the global cybersecurity field was recognized by SC Magazine in 2019, when she was named one of the top five Women of Influence in Security.

Doug Heintzman is a technology strategist with 30 years of experience in enterprise software. He consults with companies around the world on innovation and technology disruption.