East Texas A&M Builds First Implemented Post-Quantum Lightning Design

Researchers at East Texas A&M University have developed what they describe as the first implemented and experimentally evaluated post-quantum design for Bitcoin’s Lightning Network, protecting off-chain communication and payment functions without requiring changes to Bitcoin consensus.

The PQLN research, published by Ahmet Kurt, Abdul-Salem Beibitkhan, Yacoub Hanna and Abdullah Aydeger, covers Lightning gossip, peer transport, invoices, payment onions and BOLT 12 offers. The team implemented the system in rust-lightning and tested it with real Lightning nodes.

PQLN uses ML-DSA digital signatures and ML-KEM key exchange alongside Lightning’s existing cryptography. Both algorithms are standardized by the U.S. National Institute of Standards and Technology under FIPS 204 and FIPS 203.

PQLN Protects Five Lightning Surfaces

Lightning currently relies heavily on secp256k1 elliptic-curve cryptography. A sufficiently capable quantum computer running Shor’s algorithm could derive secret keys from exposed public keys, creating risks including node impersonation, forged invoices, transport decryption and payment-route deanonymization.

The system addresses the existing Lightning quantum risk without attempting to replace Bitcoin’s on-chain cryptography.

PQLN distributes post-quantum node identities through BOLT 7 gossip, adds ML-KEM to the BOLT 8 transport handshake, signs BOLT 11 invoices with ML-DSA and adds post-quantum protections to BOLT 12 offers. Payment onions under BOLT 4 retain their existing format while hybrid ML-KEM secrets are carried alongside them.

Funding, commitment and penalty transactions remain outside the system. Their keys are rooted in Bitcoin transactions and would require changes at the Bitcoin protocol level to receive equivalent protection.

Bitcoin developers are separately discussing protocol-level approaches such as BIP 360, while StarkWare demonstrated a quantum-safe transaction on Bitcoin mainnet in August without altering consensus rules.

Cryptographic Overhead Stays Below One Millisecond

Testing found that post-quantum computation added relatively little processing time. The slowest cryptographic operation measured by the researchers, ML-DSA signing, took 0.33 milliseconds.

Payments over an emulated 50-millisecond internet connection took an additional 19 to 53 milliseconds per hop. Most of that delay came from transmitting larger post-quantum data rather than performing the cryptographic calculations.

Bandwidth produced a substantially larger cost. A PQLN node downloaded roughly 10 times as much gossip data and stored about nine times as much as an unmodified node when using ML-DSA. Applying the measurements to a network with roughly 33,000 public channels would increase an initial gossip download from about 26 MB to approximately 270 MB.

Using the smaller FN-DSA-512 signature scheme reduced gossip growth to roughly four times the existing level.

Existing Lightning Nodes Remain Compatible

The researchers tested 12 configurations combining PQLN and standard Lightning nodes. Payments completed when upgraded and unmodified nodes shared a route, with connections falling back to classical cryptography when post-quantum protection was unavailable.

Operators can instead enable a mode that rejects such downgrades and stops the payment before an HTLC is sent.

The open-source implementation adds roughly 11,000 lines to a research fork of rust-lightning. Its developers describe the code as a research artifact rather than a production release, with additional interoperability testing against Core Lightning, LND and Eclair still required.

NIST has already standardized ML-KEM and ML-DSA and says organizations should begin migrating from quantum-vulnerable public-key cryptography now. Its current transition plan calls for vulnerable algorithms to be deprecated and ultimately removed by 2035, with higher-risk systems expected to transition earlier.

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