On July 22, 2020, the National Institute of Standards and Technology (NIST) announced the third-round candidates of its Post-Quantum Cryptography (PQC) Standardization Process. Seven algorithms were designated as finalists, and eight additional algorithms advanced as alternates. The finalists included four public-key encryption and key-encapsulation mechanisms (Classic McEliece, CRYSTALS-KYBER, NTRU, and SABER) and three digital signature schemes (CRYSTALS-DILITHIUM, FALCON, and Rainbow).
According to NIST’s announcement, the finalists were the algorithms considered most promising for standardization at the end of the third round. NIST noted that because CRYSTALS-KYBER, NTRU, and SABER were all structured lattice schemes, it intended to select at most one of them for the standard. The same applied to the signature schemes CRYSTALS-DILITHIUM and FALCON.
Eight alternate candidates also advanced, including BIKE, FrodoKEM, HQC, NTRU Prime, SIKE, GeMSS, Picnic, and SPHINCS+. NIST expected some alternates to be considered in a fourth round. The third phase of evaluation was estimated to last 12 to 18 months, with a detailed rationale published in NISTIR 8309.