Siemens Siemens Entrust Entrust This document describes the Internet X.509 Public Key Infrastructure (PKI) Certificate Management Protocol (CMP). Protocol messages are defined for X.509v3 certificate creation and management. CMP provides interactions between client systems and PKI components such as a Registration Authority (RA) and a Certification Authority (CA). This document obsoletes RFC 4210 by including the updates specified by CMP Updates RFC 9480 Section 2 and Appendix A.2 maintaining backward compatibility with CMP version 2 wherever possible and obsoletes both documents. Updates to CMP version 2 are: improving crypto agility, extending the polling mechanism, adding new general message types, and adding extended key usages to identify special CMP server authorizations. Introducing CMP version 3 to be used only for changes to the ASN.1 syntax, which are: support of EnvelopedData instead of EncryptedValue, hashAlg for indicating a hash AlgorithmIdentifier in certConf messages, and RootCaKeyUpdateContent in ckuann messages. In addition to the changes specified in CMP Updates RFC 9480 this document adds support for management of KEM certificates.