This document defines the Cryptographic Message Syntax (CMS) encrypted key package content type@ which can be used to encrypt a content that includes a key package@ such as a symmetric key package or an asymmetric key package. It is transport independent. CMS can be used to digitally sign@ digest@ authenticate@ or further encrypt this content type. It is designed to be used with the CMS Content Constraints (CCC) extension@ which does not constrain the EncryptedData@ EnvelopedData@ and AuthEnvelopedData.