LMS Security API

Version: 1.0.0
Last Updated: 2025-01-02
Security Classification: Stateful Hash-Based Signature
Author: MetaMUI Security Team

Overview

LMS (Leighton-Micali Signature) is a stateful hash-based signature scheme standardized by NIST, providing quantum-resistant signatures.

• Algorithm Family: Hash-based signature (stateful)
• Security Levels: 128/192/256-bit
• State Management: Critical for security
• Tree Variants: Multiple parameter sets
• Standard: RFC 8554, NIST SP 800-208

Security Warnings ⚠️

1. STATE REUSE IS FATAL: Never reuse any portion of the state
2. Sequential Signing: Must maintain strict ordering
3. Limited Signatures: Fixed number of signatures per key
4. HSS Option: Hierarchical variant available for more signatures

API Functions

Similar to XMSS with LMS-specific parameters.

Security Best Practices

• Implement hardware security module for state
• Use HSS for increased signature capacity
• Monitor signature count
• Plan for key exhaustion

Security Analysis

Threat Model: LMS Threat Model

The comprehensive threat analysis covers:

• Algorithm-specific attack vectors
• Implementation vulnerabilities
• Side-channel considerations
• Quantum resistance analysis (where applicable)
• Deployment recommendations

For complete security analysis and risk assessment, see the dedicated threat model documentation.

References

1. RFC 8554: LMS
2. NIST SP 800-208

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