This section identifies the alternative algorithms that shall be used to compute Message Integrity Check (MIC) values for PEM messages. Character string identifiers and ASN.1 object identifiers are assigned for incorporation in encapsulated "MIC-Info:" and "Key- Info:" header fields to indicate the choice of MIC algorithm employed.
A compliant PEM implementation shall be able to process all of the alternative MIC algorithms defined here on incoming messages. It is a sender option as to which alternative is employed on an outbound message.