One consideration with hash-based signature schemes is that they can only sign a limited number of messages securely, because of their use of one-time signature schemes. The US [[National Institute of Standards and Technology]] (NIST), specified that algorithms in its [[post-quantum cryptography]] competition support a minimum of 2{{Superscript|64}} signatures safely.<ref>{{Cite web |title=Submission Requirements and Evaluation Criteria for the Post-Quantum Cryptography Standardization Process |url=https://csrc.nist.gov/CSRC/media/Projects/Post-Quantum-Cryptography/documents/call-for-proposals-final-dec-2016.pdf |website=NIST CSRC}}</ref>
In 2022, NIST announced [[SPHINCS+]] as one of three algorithms to be standardized for digital signatures.<ref>{{Cite web |date=2022-07-05 |title=NIST announces four quantum-resistant algorithms |url=https://venturebeat.com/2022/07/05/nist-post-quantum-cryptography-standard/ |access-date=2022-07-10 |website=VentureBeat |language=en-US}}</ref> NIST standardized stateful hash-based cryptography based on the [[eXtended Merkle Signature Scheme]] (XMSS) and [[Leighton–Micali Signatures]] (LMS)<ref>{{citeIETF |rfcname= 8554 |title=Leighton-Micali Hash-Based Signatures}}<"rfc8554"/ref>, which are applicable in different circumstances, in 2020, but noted that the requirement to maintain state when using them makes them more difficult to implement in a way that avoids misuse.<ref>{{Cite web|url=https://csrc.nist.gov/news/2019/stateful-hbs-request-for-public-comments|title=Request for Public Comments on Stateful HBS {{!}} CSRC|last=Computer Security Division|first=Information Technology Laboratory|date=2019-02-01|website=CSRC {{!}} NIST|language=EN-US|access-date=2019-02-04}}</ref><ref>{{Cite journal |last1=Alagic |first1=Gorjan |last2=Apon |first2=Daniel |last3=Cooper |first3=David |last4=Dang |first4=Quynh |last5=Dang |first5=Thinh |last6=Kelsey |first6=John |last7=Lichtinger |first7=Jacob |last8=Miller |first8=Carl |last9=Moody |first9=Dustin |last10=Peralta |first10=Rene |last11=Perlner |first11=Ray |date=2022-07-05 |title=Status Report on the Third Round of the NIST Post-Quantum Cryptography Standardization Process |doi=10.6028/NIST.IR.8413-upd1 |url=https://csrc.nist.gov/publications/detail/nistir/8413/final |language=en}}</ref><ref>{{Cite journal |last1=Cooper |first1=David |last2=Apon |first2=Daniel |last3=Dang |first3=Quynh |last4=Davidson |first4=Michael |last5=Dworkin |first5=Morris |last6=Miller |first6=Carl |date=2020-10-29 |title=Recommendation for Stateful Hash-Based Signature Schemes |doi=10.6028/NIST.SP.800-208 |url=https://csrc.nist.gov/publications/detail/sp/800-208/final |language=en}}</ref>
