On September 6, 2022, the National Institute of Standards and Technology (NIST) issued a formal call for additional digital signature proposals to be considered in its Post-Quantum Cryptography (PQC) Standardization Process. The call was prompted by the absence of remaining non-lattice-based digital signature candidates following the third round.
According to the call for proposals, NIST stated it was primarily interested in general-purpose signature schemes not based on structured lattices, as two lattice-based signature schemes (CRYSTALS-Dilithium and FALCON) had already been selected for standardization. NIST also expressed interest in signature schemes with short signatures and fast verification for certain applications such as certificate transparency.
Submissions were due by June 1, 2023. NIST received 50 proposals, of which 40 were deemed complete and accepted for first-round evaluation. NIST indicated this process would be smaller in scope than the original PQC competition but would still require several years of analysis.