Hide Text in Photos and Send Secret Messages [Mac only]

Jackson Chung 20-08-2008

Hide Text in Photos and Send Secret Messages [Mac only] isteglogomainHave you ever wanted to send sensitive information to someone else over the internet? I’m sure you must’ve felt a little paranoid about your details getting stolen along the way. Ever wished there was a way to send messages across to a friend without others knowing? Or even not having the slightest hint that you’re sending a secret message? Do you need a way to disguise your message so that no one could tell anything from plainly looking at it?


Magicians often use this method to distract their audiences away from what is really happening — it’s called misdirection. This is mainly to get someone to focus their attention on something, while you’re performing something totally different.

I’m going to reveal a method to disguise your “sensitive” or “secret” messages within plain photos. Watch closely.

Hide Text in Photos and Send Secret Messages [Mac only] istegedphoto

The method is called steganography. It is the science of writing hidden messages in a way that only the sender and recipient will know that there even is a hidden message. Now, if I didn’t tell you that there was a message within the photo above, would you have even known? Tina also discussed steganography Become a Secret Steganographer: Hide and Encrypt your Files Read More back in June for Windows computers and her article is also definately worth reading.

The application featured here today is iSteg. As the name goes, it uses steganography to conceal messages within photos. Think of it as “invisible ink”, if you will.


Hide Text in Photos and Send Secret Messages [Mac only] isteg

Using iSteg is pretty easy. You simply enter a pass-phrase, select the picture file as the disguise, select the text file you wish to conceal within it; and click on ‘Process’. The only criteria which must be fulfilled in order for iSteg to work is:

  • Both the sender and recipient must have iSteg on their computers
  • The text file must be plain text

Everything else is set for you automatically by default.

The output photo is aptly named ‘output.jpg’. Renaming it won’t ruin the encryption so go ahead and rename it whatever you like. In order to extract the hidden message, the recipient will need to re-enter the same pass-phrase used before and select the photo with the secretly hidden message. The only change here is to uncheck the ‘Encode’ box. Then hit ‘Process’ and the message will be revealed.


Now you are able to send anything and no one will even have a clue. Just bear in mind that this method is more about the fun of sending secret messages. Don’t rely on it to encode your sensitive personal information into your photos and never expect anyone to find out.

iSteg only works on Mac OS X and is available from The source code is also available from the website.

Can anyone tell me what was hidden in the photo above?

(By) Jackson Chung is a full-time medical student attempting to perform a juggling act with relationships, studies and his future.


Related topics: Photography, Programming, Steganography.

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  1. aRt
    February 25, 2009 at 8:57 am

    The scenery is gorgeous.

    Fun app.

  2. Jackson
    August 27, 2008 at 5:23 am

    Hi hany,

    Thanks for dropping by and saying Hi. We love it when we catch the developer's attention :)

    August 26, 2008 at 5:10 am

    Hello, I'm the developer of iSteg and I would like to thank you all for your comments.
    iSteg is a mac-only application but it uses a standard open source tool called Outguess.
    Actually iSteg is a cocoa-applescript frontend for the universal binary outguess 0.2 tool.
    You can obtain source code for Outguess and build for any unix-like system on any platform. So you can exchange crypted pictures with non-mac users.


  4. Rex
    August 21, 2008 at 3:47 am

    Answer of whats encoded. Well, home has better scenery but looks nice, where is it? Password is so obvious, duh...

    • Jackson
      August 21, 2008 at 3:53 am

      Haha don't get the other readers confused. Just to explain to the rest, the secret text hidden in the photo was a question. Rex just answered it.

      Rex, it's a from a lookout point over the Remarkable Rocks in Kangaroo Island, Australia.

  5. La Blogueria
    August 21, 2008 at 3:37 am

    So, what's in there? I don't have a Mac! Anyway, the important thing was to know how to see it... thanks to all. Now I know I don´t have to watching for 40 minutes crossing eyes :D

  6. Jackson
    August 21, 2008 at 3:26 am

    Mark is right, both the sender and recipient has to have the application in order to encode and DECODE the hidden message. You can't visually see the hidden message.

    By the way, the password for that particular isteg-ed photo is makeuseof. Go ahead and give it a whirl.

  7. Flerick
    August 20, 2008 at 2:31 pm

    So, if what Mark says is indeed the truth, anyone with the program will have a way to see the secret message as well as the receiver... stupid. =[

    • Mark O'Neill
      August 20, 2008 at 2:36 pm

      but only if the person knows there is a message hidden in the picture in the first place. If I hadn't told you there was a message hidden in the picture, you would never have known, would you?

    • Kenneth
      August 20, 2008 at 3:08 pm

      only if they have the password.

    • Aibek
      August 21, 2008 at 2:19 am

      That's only because you know the password

  8. La Blogueria
    August 20, 2008 at 12:06 pm

    I'm here, refreshing each 5 minutes, waiting for the commenters to solve the mistery for me, as I can see nothing. Nothing hidden, I mean, and I read Wikipedia article and don't know what I am looking for. I want to know and understand.

    Please somebody tell me!


    • Mark O'Neill
      August 20, 2008 at 12:37 pm

      I'm pretty sure you have to install the software that Jackson is talking about and then put the picture through the software to find the secret message! :-)

      • Lebowski Guy
        August 20, 2008 at 1:00 pm

        Is there a windows version or alternative freeware program that looks as cool?

        • Aibek
          August 21, 2008 at 2:18 am

          Hmmmm, I am sure there is, though can't thing of anything specific now.

    • Jackson
      August 21, 2008 at 3:47 am

      Do you have a Mac? You'll have to download the application and the photo, then open the photo in iSteg. The password is makeuseof