Feature: Support encrypted documents

[PrinsFrank]

Currently encrypted documents are not supported. It would be really nice if we could support those. See #66 for an example file

[nnbai]

Hi,

Currently, the parser throws an exception if it encounters an encrypted PDF file. Before fully implementing support for encryption, could the parser allow to continue processing the file? It would be beneficial if the parser could at least allow navigate through pages and objects despite the encryption.

Alternatively, making the exception thrown by the Document class optional could be a solution. This way, exceptions would only be thrown when an encrypted string or stream is encountered.

Thanks,
Niranjan

[PrinsFrank]

@nnbai Thanks for reaching out! Support for encrypted documents is almost complete, I'm just running into one or two very stubborn bugs which result in the current implementation failing on password verification.

We could try to read as much info as possible and ignore encryption as far as possible, but that will result in a Backwards incompatible change as soon as proper encryption support has been added, so I'd rather focus on finishing that. You can see the current status of that in this pr: #282

I'm maintaining this library next to my full-time job, and I'm also working on some other hobby projects, so I'm juggling hobbies here. I'll take a proper stab at this soon!

[nnbai]

Perfect! Thank you for the update!
I am looking forward to see the encryption support implemented soon.