Add support for encrypting documents with an AES-128 algorithm.

From the Part 4: PAdES Long Term - PAdES-LTV Profile (ETSI TS 102 778-4) Specification: 

"Validation of an electronic signature requires data to validate the signature such as CA certificates, Certificate Revocation List (CRLs) or Certificate status information (OCSP) commonly provided by an online service (referred to in the present document as validation data). If the document is stored and the signatures are to be verifiable long after first created, in particular after the signing certificate has expired, the original validation data may no longer available or there may uncertainty as to what validation data was used when the document was first verified."

In version 1 there are three profiles that have different levels of detail in their structure: Basic (B), Comfort (C) and Extended (X): https://mind-forms.de/e-rechnung/welches-zugferd-profil-kann-ich-verwenden/ 

Add support for /TR (Transfer Function) property of SMask.

Add support for the PAdES-BES signature standard

When writing a RadFixedPage containing widgets using the PdfPageStreamWriter.WriteContent() method an exception is thrown.

The exception: System.ArgumentNullException: 'Value cannot be null. Parameter name: context'

When importing a document with an invalid creation or modification date, an exception is thrown:

• FormatException: 'The input string '' was not in a correct format.'
• ArgumentOutOfRangeException: 'Year, Month, and Day parameters describe an unrepresentable DateTime.'

Handle the import of documents when the GoToR action`s file specification object is a string.

Add support for GoToR action

Note: related item: PdfProcessing: Introduce functionality to preserve GoToR actions during import/export