
Secrets can be embedded within photo and audio files by replacing the
least essential code with bits of the hidden data. Developers have come
up with a wealth of applications that can do this work from mobile
devices and many of them are free..
Concealment: From Lakeside Llama this iOS app lets you take a picture
and hide a secret message inside of the image (up to three hidden
images). These images can then be stored in the in-app photo library,
the device photo library, iMessage (iOS 5) or be emailed directly to
whomever one is sending the message to, the company says.
Hide It In: Hide It...