Lightning creator says the quantum threat to Bitcoin is remote but cannot be ignored

Source: PortaldoBitcoin Original Title: Lightning Creator Says Quantum Threat to Bitcoin Is Remote but Cannot Be Ignored Original Link: The threat that quantum computers pose to Bitcoin is still far from materializing, but it should not be treated as science fiction. That’s how Tadge Dryja, one of the leading researchers in the Bitcoin ecosystem and co-creator of the Lightning Network—the second-layer solution used for instant payments on the network—sees the topic.

In an interview, he said he believes the disruption could take decades, but that even a small probability is still too dangerous to ignore. “I’d probably bet it doesn’t happen in my lifetime. But even if there’s only a 5% chance, that’s already bad enough that we shouldn’t stop preparing,” he said.

He also noted that Bitcoin has more of a safety margin than other technologies, since it isn’t at risk from “harvest now, decrypt later”—where governments or attackers store data today to break it in the future. “In Bitcoin, if you discover someone’s private key 30 years later, the coins have already moved. So the urgency isn’t as great as it is for emails or encrypted communications,” he stated.

Dryja is currently working on research investigating how networks like Lightning could operate securely with quantum-resistant signature schemes. He believes it’s technically possible to make the transition, but with important limitations.

“You can make a post-quantum Lightning. It’s slower, more annoying, and maybe some things would stop working. But it’s possible,” he summarized.

One potential loss involves advanced features in development, such as PTLCs—improved versions of the contracts used to route payments on Lightning. “If we need to migrate to post-quantum signatures, we might not be able to have PTLCs. That’s disappointing because they’re cool technologies we’re developing,” he said.

Dryja also highlights a structural challenge: unlike on-chain transactions, Lightning channels require thousands of repeated signatures with the same key over the channel’s lifespan. Many post-quantum algorithms don’t work well in this model. “We’re working with signature researchers to see what we can adapt. Lightning uses keys in a completely different way from traditional Bitcoin,” he explained.

Other Vulnerabilities and the Future of the Lightning Network

Beyond the quantum threat, Dryja addressed more immediate problems with the Lightning Network, a system he and Joseph Poon created in 2015 to enable instant and cheap Bitcoin payments.

According to him, the network is essentially secure regarding the theft of funds, but it remains vulnerable to denial-of-service attacks and other malicious behaviors that don’t involve direct loss of money. “The counterparty can’t steal your funds, but they can waste your time. Many Lightning attacks are like that: they close your channel, make you spend on fees. And that’s something we still don’t know how to fully solve,” he said.

Dryja also mentioned a curious scenario: the fact that few attackers actually try to exploit these weaknesses ends up leaving the network less prepared. “One of the problems with Lightning is that everyone is kind of friends. Nobody is really trying to attack much, and that makes it hard to predict how the system will handle real attacks,” he said.

On routing challenges, he points to the privacy-versus-efficiency dilemma as one of the key points in the network’s evolution. The fact that nodes don’t know channel balances makes routing more private, but much more difficult. “If we knew a bit more about balances, the network would work better. But many advocate for total privacy. It’s a complicated trade-off,” he explained.

He also spoke about technologies that could transform Bitcoin in the coming years, such as Utreexo, a project for which he is the lead researcher, and innovations like BitVM3, Ark, and new methods of encrypted transport between nodes. “The network is becoming more resilient and more efficient, often in ways the user doesn’t even notice. I think we’ll see a lot of new things in the next ten years,” he stated.