The announcement follows a six-year effort managed by NIST, which in 2016 called upon cryptographers to devise and vet encryption methods that could resist an attack from a future quantum computer that is more powerful than the comparatively limited machines available today. The selection constitutes the beginning of the finale of the agency’s post-quantum cryptography standardization project.

The algorithms are designed for two main tasks for which encryption is typically used: general encryption, used to protect information exchanged across a public network; and digital signatures, used for identity authentication. All four of the algorithms were created by experts collaborating from multiple countries and institutions. 

For general encryption, used when we access secure websites, NIST has selected the CRYSTALS-Kyber algorithm. Among its advantages are comparatively small encryption keys that two parties can exchange easily, as well as its speed of operation. 

For digital signatures, often used when we need to verify identities during a digital transaction or to sign a document remotely, NIST has selected the three algorithms CRYSTALS-Dilithium, FALCON and SPHINCS+ (read as “Sphincs plus”). Reviewers noted the high efficiency of the first two, and NIST recommends CRYSTALS-Dilithium as the primary algorithm, with FALCON for applications that need smaller signatures than Dilithium can provide. The third, SPHINCS+, is somewhat larger and slower than the other two, but it is valuable as a backup for one chief reason: It is based on a different math approach than all three of NIST’s other selections.

Three of the selected algorithms are based on a family of math problems called structured lattices, while SPHINCS+ uses hash functions. Four additional algorithms still under consideration and are designed for general encryption and do not use structured lattices or hash functions in their approaches.

Although NIST will not publish the new post-quantum cryptographic standard for use by commercial products until 2024, NIST strongly recommends security experts and their organizations to explore new algorithms and consider how their applications will use them, but not bake them into their systems yet, as the algorithms could change slightly before the standard is finalized.

However, the Cybersecurity and Infrastructure Security Agency (CISA) and NIST offer the following steps to start preparing for the transition now by following the Post-Quantum Cryptography Roadmap, which includes:

• Inventorying organization’s systems for applications that use public-key cryptography.
• Testing the new post-quantum cryptographic standard in a lab environment; however, organizations should wait until the official release to implement the new standard in a production environment.
• Creating a plan for transitioning the organization’s systems to the new cryptographic standard that includes: 
• Performing an interdependence analysis, which should reveal issues that may impact the order of systems transition;
• Decommissioning old technology that will become unsupported upon publication of the new standard; and
• Ensuring validation and testing of products that incorporate the new standard.
• Creating acquisition policies regarding post-quantum cryptography. This process should include: 
• Setting new service levels for the transition.
• Surveying vendors to determine possible integration into your organization’s roadmap and to identify needed foundational technologies.
• Alerting the organization’s IT departments and vendors about the upcoming transition.
• Educating the organization’s workforce about the upcoming transition and providing any applicable training.

For additional guidance and background, CISA and NIST strongly encourage users and administrators to review:

• NIST Announces First Four Quantum-Resistant Cryptographic Algorithms.
• The NIST and Post-Quantum Cryptography, Post-Quantum Cryptography Standardization, and Migration to Post-Quantum Cryptography websites.