Authentic Technical Gibberish

A chocolaty technology blog with a gooey center

Monthly Archives: October 2011

Viewing Encrypted PDF Documents on iOS 4.3.x Devices

The Context

I recently became a landlord (weird name if you think about it) and I had the need to send pseudo sensitive PDF documents over email to my tenants.  When I send any Personally Identifiable Information (PII) electronically I like to have a small measure of protection rather than just sending over everything “in the clear”.  I say small measure because there are a variety of ways of circumventing PDF encryption.  PDF encryption is analogous to using door knob locks in a house or TSA locks on your luggage,  the goal is to make the target annoying enough that the thief moves on to to something easier.  Once I sent these documents I had the need to view them on my iPhone.

Side Note

I use OS X exclusively for my computing needs and there are many tools for creating encrypted PDF files including the  The best program I have found to do this task, however, is PDFKey Pro.  PDFKey Pro allows you to set fine grained control over how you encrypt the document, what encryption algorithm is used, and how many bits.  PDFKey Pro’s interface is also extremely easy to use.

The Problem

When I viewed the PDF documents on my iPhone I got a blank page!  Of course I went into research mode to try to fix the problem.

The Research

I run a jailbroken iPhone running iOS 4.3.1.  My children, however, run stock iOS on their iPod Touches.  I recently upgraded their iPod’s to iOS 5 so I wanted to see if iOS 5 had this problem and after a quick test it was apparent that it did not.  After some searching on Google I ran into this post which I found intriguing.  Apparently viewing encrypted PDFs used to work on iOS 4.2.x so there was a regression from iOS 4.2.x to 4.3.x.  I am not ready to take the iOS 5 plunge on my iPhone as I am not ready to give up the particular features that I would lose in doing the upgrade.  Luckily I found a free solution and the timing couldn’t have been better.

The Solution

Adobe released their Adobe Reader software for iOS on October 17th, 2011.  After downloading the app from the App Store I opened up the documents easily using the “Open In…” feature of iOS.