One "Key-Info:" field is included for each of a message's named recipients. In addition, it is recommended that PEM implementations support (as a locally-selectable option) the ability to include a "Key-Info:" field corresponding to a PEM message's originator, following an Originator-ID or "Originator-Certificate:" field and before any associated Recipient-ID fields, but inclusion of such a field is not a requirement for conformance with this RFC.
Each "Key-Info:" field is interpreted in the context of the most recent preceding Originator-ID, "Originator-Certificate:", or Recipient-ID field; normally, a "Key-Info:" field will immediately follow its associated predecessor field. The "Key-Info:" field's argument(s) differ depending on whether symmetric or asymmetric key management is used for a particular recipient.