application/pkcs7-mime

Single S/MIME body wrapping a CMS blob, as opposed to a detached signature.

Definition

Unlike multipart/signed, application/pkcs7-mime puts the whole CMS into a single part that is not readable in the clear. The smime-type parameter states its purpose: enveloped-data (encryption), signed-data (opaque signature), or compressed-data. A name parameter suggests a filename, conventionally smime.p7m.

Origin

Defined in RFC 8551 (S/MIME 4.0 Message Specification, IETF, 2019), built on RFC 5652 (CMS).

Example in context

Content-Type: application/pkcs7-mime; smime-type=enveloped-data; name="smime.p7m"

Related terms

• EnvelopedData — encrypted CMS content.
• CMS — underlying binary syntax.