Since to sign a PDF you forced the implementation of the SignatureInterface interface, is not possible to prepare N hashes from N PDF files and then send them to a signing service that accepts multiple hashes with a single signon.
For example if I use an OTP signing service.
What would be nice to have is to separate the hash calculation from the signing.
Instead to implement the Interface I would like to have something like this:
1) calculate hash from document with the new signature dictionary bytes
2) sign the hash
3) insert the signature into pdf
This way I could achieve to sign for example 100 pdf files calling the service once.
Right now must ask the user to sign in 100 times.
Thanks in advance.