🚀 go-pugleaf

Sorry, just so that I can clear up what's happening in my head:

1) You have a PDF file that is encrypted with AES by an external application, not using Acrobat's internal AES encryption.

2) You want to write a plug-in that will identify these files, decrypt them, and then read the decrypted stream from memory and open it in the Acrobat viewer.

This is certainly possible, but by no means trivial. You would need to write your own handler to identify the encrypted files, decrypt them using your own implementation of AES (there are open-source libraries available you could use) and then write your own ASFileSys to read the unencrypted stream from memory.

This begs the question - as of Acrobat 9, 256-bit AES encryption is supported by Acrobat natively. Why not just use the existing functionality? You can even write your own PDCryptHandler interface to it if you want to replace the existing interface, and that is still much less work than you are describing above.