File camouflage is a computer technique to hide secret information in a file.
Most of the file formats have some redundant portions where any confidential data could be inserted intentionally. For example, JPEG, MP3, and Microsoft Word files don't care whatever extra data are added at the end of the file. Added data can further be encrypted, making it even more difficult for ordinary computer users to notice it.
File Camouflage (aka, File Deception) is a technique to hide confidential data by inserting it in such redundant part of a file. A camouflaged file works normally in ordinary use.
File camouflaging uses two types of programs, i.e., an encoder to insert a confidential data, and a decoder to extract the inserted data, sometimes a password is needed to extract the secret information. An example of this is the program steghide. This program allows users to embed data in many different files. Another example of File Camouflage is jpegx, this program allows users to hide data specifically in JPEG files.
A "camouflaged" file often increases so much in size that it is not difficult for experts to detect and remove the inserted data. Because of this it is not a very safe technique to hide confidential information in a computer.