The password-based standard security handler of the PDF specification, identified by a /Filter value of /Standard.
The PDF specification defines one security handler that should be implemented by all PDF conform libraries and applications. This standard security handler allows access permissions and a user password as well as an owner password to be set. See StandardSecurityHandler::EncryptionOptions for all valid options that can be used with this security handler.
The access permissions (see StandardSecurityHandler::Permissions) can be used to restrict what a user is allowed to do with a PDF file.
When a user or owner password is specified, a PDF file can only be opened when the correct password is supplied.
See: PDF1.7 s7.6.3, PDF2.0 s7.6.3
The padding used for passwords with fewer than 32 bytes. Only used for revisions <= 4.
See: PDF1.7 s184.108.40.206