SPHINCS+
What is SPHINCS+?
SPHINCS+A stateless hash-based digital-signature scheme standardized by NIST as FIPS 205 (SLH-DSA) in August 2024, offering conservative post-quantum security with no structured-math assumptions.
SPHINCS+ is a stateless hash-based signature scheme that combines few-time Winternitz signatures with hypertrees and FORS, deriving its security purely from the properties of an underlying hash function (SHA-2 or SHAKE). Because the security argument relies only on hash-function assumptions, it is the most conservative NIST PQC choice and a useful hedge against future cryptanalysis of lattice problems. NIST finalized it as FIPS 205 (SLH-DSA) in August 2024 with multiple parameter sets balancing signature size (around 8-50 kB) against signing speed. Typical use cases include long-lived firmware and software signing, where verification cost is acceptable and longevity matters most.
● Examples
- 01
Used for firmware-update signing on devices that must remain trustworthy for decades.
- 02
Selected as the hash-only fallback signature in PQC migration plans for code signing.
● Frequently asked questions
What is SPHINCS+?
A stateless hash-based digital-signature scheme standardized by NIST as FIPS 205 (SLH-DSA) in August 2024, offering conservative post-quantum security with no structured-math assumptions. It belongs to the Cryptography category of cybersecurity.
What does SPHINCS+ mean?
A stateless hash-based digital-signature scheme standardized by NIST as FIPS 205 (SLH-DSA) in August 2024, offering conservative post-quantum security with no structured-math assumptions.
How does SPHINCS+ work?
SPHINCS+ is a stateless hash-based signature scheme that combines few-time Winternitz signatures with hypertrees and FORS, deriving its security purely from the properties of an underlying hash function (SHA-2 or SHAKE). Because the security argument relies only on hash-function assumptions, it is the most conservative NIST PQC choice and a useful hedge against future cryptanalysis of lattice problems. NIST finalized it as FIPS 205 (SLH-DSA) in August 2024 with multiple parameter sets balancing signature size (around 8-50 kB) against signing speed. Typical use cases include long-lived firmware and software signing, where verification cost is acceptable and longevity matters most.
How do you defend against SPHINCS+?
Defences for SPHINCS+ typically combine technical controls and operational practices, as detailed in the full definition above.
What are other names for SPHINCS+?
Common alternative names include: SLH-DSA, FIPS 205.
● Related terms
- cryptography№ 846
Post-Quantum Cryptography
Classical cryptographic algorithms designed to remain secure against attacks by both classical and large-scale quantum computers.
- cryptography№ 247
Cryptographic Hash Function
A deterministic one-way function that maps arbitrary-length input to a fixed-length digest, designed to be collision-, preimage-, and second-preimage-resistant.
- cryptography№ 321
Digital Signature
A public-key cryptographic mechanism that proves the authenticity, integrity and non-repudiation of a message or document.
- cryptography№ 252
CRYSTALS-Dilithium
A lattice-based digital-signature scheme standardized by NIST as FIPS 204 (ML-DSA) in August 2024 and intended as the post-quantum replacement for RSA, DSA, and ECDSA signatures.
- cryptography№ 404
Falcon (Signature Scheme)
A lattice-based post-quantum signature scheme over NTRU lattices, selected by NIST in 2022 for compact signatures and now being finalized as FIPS 206 (FN-DSA).
- cryptography№ 732
NIST PQC Standardization
The multi-year NIST process that selects and standardizes post-quantum cryptographic algorithms; its first three standards, FIPS 203, 204, and 205, were published in August 2024.