Cryptographic Message Syntax (CMS) Content Constraints Extension

This document specifies the syntax and semantics for the CryptographicMessage Syntax (CMS) content constraints extension. This extension isused to determine whether a public key is appropriate to use in theprocessing of a protected content. In particular, the CMS contentconstraints extension is one part of the authorization decision; it isused when validating a digital signature on a CMS SignedData contentor validating a message authentication code (MAC) on a CMSAuthenticatedData content or CMS AuthEnvelopedData content. The signedor authenticated content type is identified by an ASN.1 objectidentifier, and this extension indicates the content types that thepublic key is authorized to validate. If the authorization check issuccessful, the CMS content constraints extension also providesdefault values for absent attributes.