2.20. Update Section 7 - Version Negotiation

2.20. Update Section 7 - Version Negotiation

Section 7 of [RFC4210] describes the use of CMP versions. This document describes the handling of the additional CMP version cmp2021, which is introduced to indicate support of EnvelopedData and hashAlg.

Replace the text of the second paragraph with the following text:

If a client knows the protocol version(s) supported by the server (e.g., from a previous PKIMessage exchange or via some out-of-band means), then it MUST send a PKIMessage with the highest version supported by both it and the server. If a client does not know what version(s) the server supports, then it MUST send a PKIMessage using the highest version it supports with the following exception. Version cmp2021 SHOULD only be used if cmp2021 syntax is needed for the request being sent or for the expected response.

Note: Using cmp2000 as the default pvno is done to avoid extra message exchanges for version negotiation and to foster compatibility with cmp2000 implementations. Version cmp2021 syntax is only needed if a message exchange uses hashAlg (in CertStatus) or EnvelopedData.