Adobe Reader XI search fail when pdf fileIdentifier (/ID) is set

Question

I am part of the R&OS pdf class for php developer team and noticed some strange behavior in Adobe Reader XI (11.0.5)

When a pdf file includes the fileIdentifier (/ID entry in trailer part) Adobe Reader failed to search for the text content.

Once I remove the /ID entry search is fully functioning.

Foxit Reader and Chrome reader search worked in both cases

Does anybody know why Adobe Reader (AAR) is behaving like this?

In addition I added both pdf files on pastebin.com. So you can download and test from there. Simple store it with the extension ".pdf"

http://pastebin.com/an5NaZcv - search failed

http://pastebin.com/ZyFZNQ36 - search ok

BINARY FILE WHICH IS NOT WORKING: bug is fixed

I reported this as bug in my application here: https://sourceforge.net/p/pdf-php/bugs/71/

Thank you in advanced

Answer 1

I am pretty much sure I solved it by clearing the fast search cache in Adobe Reader.

My explanation why this problem occurs:

Even without encryption, the fast find feature from Adobe Reader is using the /ID entry (if it is set) to somehow identify all text content of the document.

Once I have cleared the fast find cache from "Preferences -> Search" I was again able to search

So in future I will use something similar to md5(#timestamp#) to make sure every document has its own unique fileIdentifer stored in /ID entry of the document trailer.

Thank you for your hints

Regards, Ole