The Butterfly Protocol: Secure Symmetric Key Exchange and Mutual Authentication via Remote QKD Nodes
| Accepted | January 2026 |
|---|---|
| Authors | Sergejs Kozlovičs, Elīna Kalniņa, Juris Vīksna, Krišjānis Petručeņa, Edgars Rencis |
| Venue | Symmetry |
| DOI | 10.3390/sym18010153 |
This article introduces the Butterfly Protocol and an extended variant that allow QKD to be delivered as a service to non-QKD-capable devices, including portable and IoT systems. Key contributions include resilience against compromise of any single classical link, protection against malicious QKD users, implicit mutual authentication without dependence on large post-quantum certificates, and the Double Butterfly extension for scenarios with partially untrusted QKD infrastructure. The paper also describes TLS 1.3 integration, provides initial security analysis, and reports preliminary performance observations and implementation bottlenecks.