A groundbreaking new approach could help secure fast, off-chain Bitcoin transactions against the cybersecurity threats of tomorrow.

A future quantum computer powerful enough to threaten Bitcoin does not exist yet. But researchers at East Texas A&M University and three other institutions have already built and tested a defense against one of the threats it could pose.

Dr. Ahmet Kurt, an assistant professor in East Texas A&M's Department of Computer Science and Information Systems, and his collaborators have developed what they say is the first post-quantum design, implementation and evaluation for the Bitcoin Lightning Network.

And this is more than a theory about what might work someday.

Their work is detailed in the paper “PQLN: Post-Quantum Security for the Bitcoin Lightning Network's Off-Chain Surfaces,” published in September on arXiv, a digital archive where researchers share drafts of scientific papers before they undergo formal peer review. Kurt collaborated with Abdul-Salem Beibitkhan, a North American University graduate; Dr. Yacoub Hanna, an assistant professor at Florida Gulf Coast University; and Dr. Abdullah Aydeger, an assistant professor at Florida Institute of Technology.

Preparing Today for the Computers of Tomorrow

Bitcoin is the world's largest cryptocurrency, but transactions made directly through its blockchain can be relatively slow and costly. The Lightning Network was developed to address that problem.

Kurt compares the idea to the network that makes everyday credit card purchases possible. Instead of recording each payment directly on the Bitcoin blockchain, Lightning allows users to make payments through a network of channels. A payment can travel directly between two connected users or pass through other users until it reaches its destination.

“So this is the main idea of Lightning,” Kurt said. “It's pretty cool.”

But the cryptography protecting Bitcoin and Lightning faces a potential problem: quantum computing.

Quantum computers use a fundamentally different approach to computation than conventional computers. Although today's computers are not capable of breaking Bitcoin's cryptography, researchers are preparing for the possibility that sufficiently powerful machines could eventually do so.

For Lightning, that could create threats even if Bitcoin itself were someday upgraded with post-quantum protections. Lightning has its own communications and payment systems that would also need to be secured.

There is another reason researchers are working on the problem now. An attacker does not necessarily have to wait for a powerful quantum computer to begin an attack.

Kurt described a scenario in which someone records encrypted Lightning communications today. The attacker cannot read the information, so it is simply stored. Years later, however, a sufficiently powerful quantum computer could potentially decrypt that saved information, revealing details about past transactions.

It is a cybersecurity strategy known as “harvest now, decrypt later.”

Building a Solution—and Proving It Works

Kurt and his colleagues developed PQLN, or Post-Quantum Lightning Network, to protect parts of Lightning that operate outside the Bitcoin blockchain.

The researchers incorporated post-quantum cryptography into Lightning's communications, payment requests and other systems. They then implemented their Rust-Lightning design, in one of the major implementations of the Lightning Network

For Kurt, that meant months of hands-on work.

“It took a bit of time, like three, four months, at least, to properly implement it and then make sure that it was working,” he said.

The result was approximately 11,000 lines of added code and, importantly, a complete working implementation rather than a small-scale demonstration.

Testing brought another encouraging result. Kurt expected the post-quantum protections to significantly slow the system. Instead, the additional cryptographic operations took no more than 0.33 milliseconds in the researchers' tests.

The larger challenge involved data size. Post-quantum cryptography requires substantially more information to be transmitted, increasing the amount of network traffic generated when Lightning nodes communicate with one another. Depending on the cryptographic approach, the researchers found that this traffic increased approximately fourfold to tenfold.

The team also addressed one of the largest practical obstacles facing any major technological change: Not everyone will upgrade at once.

Kurt designed PQLN so that upgraded nodes can continue communicating with existing Lightning nodes. When two PQLN-enabled nodes communicate, they can use the new post-quantum protections. If one has not been upgraded, communication can continue using the existing system.

That interoperability could allow post-quantum technology to be introduced gradually instead of requiring the entire Lightning Network to change at once.

The researchers emphasize that PQLN does not make Bitcoin itself quantum-proof. Protecting Bitcoin's underlying blockchain would require separate changes. Instead, their work demonstrates that Lightning's off-chain systems can begin preparing for the quantum era independently.

Research With Real-World Reach

For Kurt, the project reflects the kind of emerging technology research taking place within East Texas A&M's Department of Computer Science and Information Systems.

The department prepares students for careers and research in areas including cybersecurity, artificial intelligence, programming, computer networks, digital forensics, data analytics and machine learning.

Kurt is based at the RELLIS Campus in Bryan, where East Texas A&M is one of the universities offering programs through the Texas A&M-RELLIS Academic Alliance. The university offers computer science-related programs at RELLIS, placing students alongside faculty members engaged in research on rapidly changing technologies and cybersecurity challenges.

PQLN may also be only the beginning.

The researchers implemented their system using Rust-Lightning, but Kurt said the approach could now be adapted for the other major Lightning implementations. More broadly, researchers and developers continue working on the challenge of preparing Bitcoin and related technologies for a future in which quantum computers could render some of today's cryptography obsolete.

News of the research quickly gained traction on X, where posts about the team's work circulated widely among cryptocurrency and technology communities.

For Kurt, whose research focuses heavily on Bitcoin, the Lightning Network and cybersecurity, seeing the project attract international attention has also provided a reminder of why he chose an academic career.

“It feels amazing,” Kurt said. “It reminds me of why I do this. Being recognized by your peers for your work is the best feeling you can have as a researcher.”

And in this case, that research is looking beyond the technology of today—toward protecting a global financial network from computers that have not even been built yet.