Steg is a cross-platform and portable software, written in C++. It use steganography and cryptography techniques to hide information inside uncompressed and compressed images. JPEG (JPG), TIFF, PNG, BMP image formats are supported. It really hides arbitrary data inside the image itself (not in metadata/comment fields or appended to the end of the file). With it's easy graphical user interface is possible to fine tune steganography parameters, evaluates image's artifacts and uses both symmetric-key and asymmetric-key cryptography. Arbitrary data can be hidden as compressed archive file and it's also possible to add a text comment.  Steg runs on GNU/Linux, Microsoft Windows and Apple Mac OS X. More info-Steg