NAC

Initial vector is required by some block ciphers. EncryptedContent abstraction should have InitialVector as an optional field.

The updated EncryptedContent format would be:

EncryptedContent     ::= ENCRYPTED-CONTENT-TYPE TLV-LENGTH
                         KeyLocator // name of encrypting key
                         EncryptionAlgorithm
                         InitialVector?
                         EncryptedPayLoad
EncryptionAlgorithm  ::= ENCRYPTION-ALOGRITHM-TYPE TLV-LENGTH
                         nonNegativeInteger // algorithm id
InitialVector        ::= INITIAL-VECTOR-TYPE TLV-LENGTH 
                         BYTE+
EncryptedPayLoad     ::= ENCRYPTED-PAYLOAD-TYPE TLV-LENGTH 
                         BYTE+