Multi-Armed SPHINCS+

SPHINCS+ is a quantum-resistant, stateless hash-based signature scheme standardized by NIST. Despite its strong security guarantees, it suffers from:

• Large signature sizes
• Slow signing processes

This paper focuses on mitigating the signing latency by leveraging:

• The multi-core Snapdragon 865 Mobile Platform
• Vector extensions for parallel processing

Key results:

• Achieves up to 15× speed-up over non-vectorized implementations
• Demonstrates side-channel protected versions using vectorized SHAKE-based SPHINCS+
• Suggests hash-based signatures are viable even on constrained mobile devices with proper parallelization

This work bridges secure PQ signatures and efficient mobile deployment.