By Graham K. Rogers

When I was trying to find information for a class I was teaching Computer Engineering students on ethics and morals in 2010, I decided to include the ideas behind steganography: secret writing. Text can be hidden inside an image file and it is largely undetectable.

Background

I wrote about this at some length at that time and there were two articles in the Bangkok Post (both still on my website): Steganography on the Mac Hiding data in images; and Steganography on the Mac (2): Some Shortcomings.

As well as an outline of the technology, I looked at some apps available for the iPhone and the Mac. The best of these (with some limits) was StegoSec, Italian-developed software that was able to encrypt and decrypt with no serious problems. There may be limits as to the amount of text that can be included as I found with some of the apps I looked at, but a useful three paragraphs could be handled without difficulty (see below).

There were minor problems with using the app -- the interface needed some work -- but it was an interesting demonstration of the concept and there were a number of ways in which the files created could be handled. This also had the advantage that there was also a StegoSec application for the Mac, so files were usable there too.

Update

• Supports all UTF-8 characters
• Adds support for Japanese, modern Chinese (that may be "simple Chinese), Arabic and many other character sets

and there are also Stability fixes reported.

Encryption

At the top of the menu panel is Decryption -- finding out what is in an image. The encryption (or Crypt Image) allows the use of a photograph in the iPhone Library or an image from the camera. Once the image is selected, "Next" at the top of the panel takes a user to the next step which is a box for entering text. This time I tried to include the entire 850 words or thereabouts from my original Steganography article, but after entering a password (twice) and a file name in the next step, the app crashed each time. Smaller blocks of text were not a problem, so there is a limit.

Decryption

It is in this panel that export functions may be accessed using another button. Once an image is displayed in the panel, pressing "Send Image" allows email, Clipboard and SMS exports to be made. This is a considerable improvement from the original version I looked at.

To decrypt any image that is displayed in the panel we press "Decrypt" (in the same location as "Next") and are faced with a Password box. When entered, a Go button is pressed and the text appears in the larger box below. This still had the problem that the keyboard remained over the box, but enough is visible for viewing and Copy and Paste to be carried out.

Comments

I note also that the version of the application for OS X has been updated to version 1.1. I had been running 1.0. It now supports MacOS X 10.7 Lion, 10.6 Snow Lopard or 10.5 Leopard. Intel only (32/64 bit). The previous version which supports PowerPC is still available for download.

The new version of the iOS app shows considerable development, particularly to the user interface. The amount of text that can be used within an image has limitations, but there are other routes for sending large files should this be needed. As a quick method of secure transmission of data from the iPhone, this is an interesting solution.

Graham K. Rogers teaches at the Faculty of Engineering, Mahidol University in Thailand. He wrote in the Bangkok Post, Database supplement on IT subjects. For the last seven years of Database he wrote a column on Apple and Macs.