LULA I: Rollback-Resilient Hash-Based Signatures with Cache-Accelerated Signing

LULA is Ring0 Labs’ research family of hash-based signature schemes. LULA I produces 5,720-byte signatures. With a 72 MiB signing cache, median signing takes 3.59 ms for 32-byte messages; median verification takes 0.12 ms. Loading a saved cache and producing the first signature takes 5.70 s median. After complete cache loss, three first-signature runs took 330–338 s. The paper examines these memory–latency tradeoffs and compares measured implementations. Rollback-security transfer is conditional; full reference-signer security remains open.