The Trail of Bits cryptography team is pleased to announce the open-sourcing of our pure Rust and Go implementations of Leighton-Micali Hash-Based Signatures (LMS), a well-studied NIST-standardized post-quantum digital signature algorithm. Hash-based signature schemes have much longer signatures than lattice-based signature schemes, which were recently standardized by NIST, but they are simpler to implement and require fewer novel cryptographic assumptions. The main benefit of a stateful algorithm like LMS over a stateless hash-based signature like SLH-DSA (SPHINCS+) is significantly shorter signature sizes: a signature with LMS is around 4KB, while a signature with SLH-DSA at a similar security level is closer to 40KB.