NIST publishes its updated guidance on crypto agility
4 MARCH 2025, GAITHERSBURG
NIST Cybersecurity White Paper 39, "Considerations for Achieving Cryptographic Agility: Strategies and Practices," examines how organizations can replace and adapt cryptographic algorithms in protocols, applications, software, hardware, firmware and infrastructure while keeping systems running. Practitioners call this ability to swap algorithms crypto agility. NIST released the initial public draft on 4 March 2025, with updates on 5 March, and took comments through 30 April 2025. NIST also said it planned a virtual workshop to help stakeholders develop sector-specific crypto agility strategies. A second public draft followed on 17 July 2025.
NIST published a final version on 19 December 2025. NIST's record for the update, CSWP 39upd1, gives its date as 29 June 2026 and says it supersedes the 19 December 2025 final. The upd1 record is therefore the current publication, not the December final or the second public draft. It lists nine contributors from NIST, Vigil Security, Strativia and Trusted Cyber Annex, including Elaine Barker, Lily Chen, David Cooper and Dustin Moody, and covers cryptographic agility, algorithms, APIs, risk management and transition strategies.
The paper responds to the need to migrate algorithms because of quantum computing and other emerging threats, and it surveys trade-offs, challenges and operational mechanisms. It also fed the maturity-model thinking that practitioners use to assess crypto agility.
The paper speaks to security architects, product teams and standards bodies planning for algorithm change, and to federal agencies facing the 2026 migration deadlines.
Why it matters. Crypto agility determines how costly the next algorithm change will be, so this paper is a practical reference for architecture and procurement decisions. Executives should expect auditors and boards to ask whether critical systems can change algorithms without replacement. The guidance is a NIST white paper, not a mandate.