NIST Advances 9 Post‑Quantum Signature Algorithms to Round 3

This diversity is intentional: NIST typically evaluates candidates from different mathematical foundations so that a weakness discovered in one family does not undermine the entire post‑quantum ecosystem.

Candidates eliminated after Round 2

Before this announcement, 14 algorithms had advanced to the second round of the additional‑signatures process.

The following five candidates did not move forward to Round 3:

• CROSS
• LESS
• Mirath
• PERK
• RYDE

Earlier documentation grouped these schemes into several approaches, including code‑based designs (CROSS, LESS) and MPC‑in‑the‑Head constructions (Mirath, PERK, RYDE).

The provided sources confirm that these algorithms were part of the previous round but do not include NIST’s detailed technical reasons for eliminating them, such as potential security concerns, performance issues, or implementation complexity. As a result, the precise evaluation rationale is not specified in the available evidence.

What happens in the third round

According to NIST’s announcement, the nine remaining algorithms will proceed to further analysis and evaluation in Round 3.

The supplied sources confirm that the third round follows approximately 18 months of evaluation but do not include detailed information about allowed specification updates or the full timeline extending through 2027.

Typically in NIST cryptographic competitions, later rounds involve deeper scrutiny of:

• security assumptions and resistance to new attacks
• implementation efficiency across hardware and software platforms
• signature size, key size, and verification speed
• suitability for real‑world deployment

However, the exact update rules and deadlines for this specific stage are not described in the sources provided.

Why this decision matters

The announcement fits into a broader global effort to secure digital systems against future quantum computers, which could break widely used cryptographic systems such as RSA and elliptic‑curve cryptography.

In August 2024, NIST published its first official post‑quantum cryptography standards:

• FIPS 203: based on CRYSTALS‑Kyber (key encapsulation)
• FIPS 204: based on CRYSTALS‑Dilithium (digital signatures)
• FIPS 205: based on SPHINCS+ (hash‑based signatures)

NIST also selected FALCON for future publication as FIPS 206, which is still under development.

The Additional Digital Signatures project exists because the first batch of standards does not cover every use case. By continuing to evaluate more algorithms, NIST aims to:

• increase cryptographic diversity
• provide options optimized for different platforms and constraints
• reduce systemic risk if vulnerabilities emerge in one family of algorithms

In short, the nine algorithms now in Round 3 represent the next generation of candidates that could eventually become official post‑quantum digital signature standards, helping governments, companies, and infrastructure providers prepare for the quantum era.