Represents an encoding of the signature value and key information in the signature dictionary.
(PDF 2.0) The Content shall be a DER-encoded CMS binary data object containing the signature, conform to RFC 5652 Cryptographic Message Syntax and follow one of two profiles denoted as PAdES-E-BES (Basic Electronic Signature) and PAdES-E-EPES (Explicit Policy Electronic Signature). These are defined to be compatible with the corresponding profiles defined in ETSI EN 319 122-2 (i.e., CAdES-E-BES and CAdES-E-EPES, respectively).
The original signed message digest over the document’s byte range shall be incorporated as the normal CMS SignedData field. No data shall be encapsulated in the CMS SignedData field.
At minimum the CMS object shall include the signer’s X.509 signing certificate. This certificate shall be used to verify the signature value in Content.
(PDF 2.0) Signature is a document timestamp. The Content shall be the TimeStampToken as specified in RFC 3161 as updated by RFC 5816. The value of the messageImprint field within the TimeStampToken shall be a hash of the bytes of the document indicated by the ByteRange and the ByteRange shall specify the complete PDF file contents (excepting the Content value).
The Content format is unknown.