A new research paper called “PQLN: Post Quantum Security for the Bitcoin Lightning Network’s Off-Chain Surfaces” by East Texas and A&M students introduces a way to shield the Bitcoin Lightning Network from future threats caused by quantum computers.
BREAKING: East Texas A&M students have built quantum-proof protection for the Bitcoin Lightning Network.
Their solution adds encryption that quantum computers cannot break, protecting Lightning payments without changing Bitcoin itself. PIC.TWITTER.COM/CYD0HRQC98
— Ash Crypto (@AshCrypto) SEPTEMBER 22, 2026
The study focuses on parts of the Lightning Network that do not operate directly on Bitcoin’s main blockchain, including gossip messages, peer communication, invoices, offers and payment onions. The team describes PQLN as a first version that brings post-quantum cryptography to these areas, but it does not remove the current security systems, it works alongside them.
Instead of trying to make all of Bitcoin completely safe against quantum computers, the researchers focus only on Lightning off-chain communication and payment methods. They built PQLN into the rust lightning software and tested it using real Lightning nodes.
According to the paper, they wrote about 11,000 lines of code spread across 52 files, so this is not just an idea on paper, it is something real you can test.
What PQLN Changes in the Lightning Network
The researchers point out several spots in Lightning that could become weak points if quantum computers get strong enough. They list things like how information moves around the network, how nodes talk directly to each other, how invoices and offers are sent, and the onion system for payments.
With PQLN, all these parts get extra protection, but they still work with the current Lightning design. PQLN does not replace the current cryptography. Instead, it uses both: what is already there and new post quantum tools.
Basics like ECDSA, Schnorr signatures, and ECDH stick around, but now ML-DSA is used for digital signatures and ML-KEM for key agreement. Those are the post quantum algorithms the team chose for this system.
One big challenge was the size of the cryptographic data. Post quantum signatures are a lot bigger than regular ones. For example, a single ML-DSA-44 signature is 2,420 bytes long, but the BOLT 11 field (where this data usually goes) only has room for 639 bytes.
So, PQLN splits the signature into pieces rather than trying to fill it all in at once. ML-KEM also creates a size problem. Its ciphertext weighs in at 1,088 bytes, and the Lightning payment onion only allows a total of 1,300 bytes. To get around this, PQLN carries the ciphertext outside the onion message, instead of trying to fit everything inside.
The Cost of Adding Post-Quantum Protection
The research makes it clear that bringing in post-quantum security is not free, you pay with extra communication overhead. Running the crypto itself is pretty fast in their tests, usually taking 0.33 milliseconds or less. But post quantum signatures and ciphertexts are much bigger, so they use up more bandwidth.
When you send a payment through Lightning with the new protection, it takes less than 60 milliseconds per hop on a regular internet connection. So, the time spent is not really the problem, it is mainly about moving more data between nodes. Gossip traffic is where the size difference really shows. The paper says that, with ML-DSA, gossip messages can get about 10 times bigger. Since Lightning relies on gossip to spread network information, this means more bandwidth for everyone.
Security Assumptions and Remaining Limits
The security of PQLN depends on how public keys get trusted in the first place. The researchers point out that you still need a safe way to get rid and pin down each other’s keys before any powerful quantum computer is around. That is because post quantum algorithms by themselves can’t solve every trust problem, getting keys from a reliable source still matters.
The paper also does not claim to solve all of Bitcoin’s quantum risks. PQLN does not touch on-chain funds; it does not change the cryptography that protects Bitcoin coins on the main blockchain. Those still use secp256k1, and protecting them would need bigger changes to Bitcoin itself, not just a tweak to Lightning’s off-chain parts.
In short, the research offers PQLN as a step to migrate Lightning’s off-chain areas to post quantum safety. The team shows how you can mix in new signatures, key methods, and hybrid security while working with strict size limits and dealing with the extra traffic that comes from larger crypto data.
