Proper method to extract the hash from a PDF file?

[marTi]

It should be enough to use the right mode.

You can use this as a reference: https://hashcat.net/wiki/doku.php?id=example_hashes

thanks. Atom, can you share regexp that is used by hashcat to verify that certain PDF hash is correct? Thanks in advance.

[atom]

Well, there is no regexp in hashcat. But using my reference you should be able to write your own