decoding algorithm wanted

Question

I receive encoded PDF files regularly. The encoding works like this:

• the PDFs can be displayed correctly in Acrobat Reader
• select all and copy the test vi

Answer 1

It's only possible then you have a lot of examples (examples count stops then: possible to get all the combinations or just an linear values dependency or idea of the scenario).

also this question : How would I reverse engineer a cryptographic algorithm? have some advices.