Hash-Based Cryptography
Definition
Hash-based cryptography constructs digital signatures using only cryptographic hash functions as security primitives. This approach provides the most conservative post-quantum security assumptions—if the underlying hash function is secure, so is the signature scheme. SPHINCS+ is the primary NIST hash-based standard.
Technical Explanation
Hash-based signatures work by committing to many potential one-time signatures organized in Merkle trees. Signing reveals one-time signature components while the tree structure proves authenticity. Key components include: WOTS+ (Winternitz One-Time Signatures) for individual signatures, Merkle trees for public key compression, and FORS (Forest of Random Subsets) for few-time signing.
Security relies on hash function properties: collision resistance, preimage resistance, and second preimage resistance. Grover's algorithm provides only quadratic speedup, easily countered by doubling hash output size. SHA-256 or SHAKE256 suffice for quantum resistance.
SynX Relevance
SynX implements SPHINCS+ hash-based signatures for transaction authorization. This choice prioritizes long-term security confidence over signature size optimization. No algebraic structure means no algebraic attacks—hash-based security has the simplest, most verifiable assumptions.
Frequently Asked Questions
- Why not use hash-based encryption too?
- Efficient hash-based encryption doesn't exist; hash functions are one-way by design.
- Are hash-based signatures slow?
- Signing is slower than lattice alternatives but still milliseconds—acceptable for transactions.
- Why are signatures large?
- Without algebraic structure, more data is needed to prove authenticity.
Maximum signature security confidence. Sign with SPHINCS+ on SynX