Introduction This document defines the syntax for private-key information and a Cryptographic Message Syntax (CMS) [RFC5652] content type for it. Private-key information includes a private key for a specified public-key algorithm and a set of attributes. The CMS can be used to digitally sign@ digest@ authenticate@ or encrypt the asymmetric key format content type. This document obsoletes PKCS #8 v1.2 [RFC5208].