This topic is Dangerous.
The art and science of communicating in a way which hides the existence of the communication (Obfuscates). In computers, this usually involves hiding one file inconspicuously inside another. There are many applications designed to hide and detect, information inside a file. Steganography can used to write a fingerprint/signature in data which is useful to proof authenticity and/or claim copyright.
- External list of software: List of steganographic tools usually freely available on the Internet. Several of them come with source code.
- Local list:
This list is not exhaustive.
- StegHide - for Windows and Linux - "embeds a secret message in a cover file (JPG, BMP, AU, WAV) by replacing some of the least significant bits of the cover file with bits of the secret message. After that, the secret message is imperceptible and can only be extracted with the correct passphrase. To increase invisibility the hidden bits are encrypted (using the blowfish encryption algorithm) and pseudo-randomly spread in the stego file." GPL, parts are LGPL, Sourceforge hosting.
- OutGuess (Mirror; official homepage is http://www.outguess.org which is down at the time of writing) - BSDL. Can write a secret message in a PNM or JPEG. The homepage also hosts Stegdetect, a tool which detects hidden content in JPG images.
- appendX - CLI tool for Linux and Windows. Written in Perl. Supports at least PNG, JPG and GIF.
- Snowdrop - GPL. "A steganographic text document and C code watermarking tool that uses redundant, tamper-evident and modification-proof information embedded in the content itself, instead of the medium, to simplify tracking of proprietary code leaks, sensitive information disclosure, etc."
- Shadow-JPEG GPL tool for JPEG steganography.
- Hide in Picture for DOS and Windows - "A program that allows you to conceal files inside bitmap pictures, using a password. The pictures look like normal images, so people will not suspect there is hidden data in them." GPL, SourceForge hosting.
- Lazy Encryption Algorithm - BSDL. LEA is a simple algorithm for file encryption that uses boolean algebra and modular arithmetic to test the stream and generate numbers with a logical order. Using bytes as increments and decrements users can choose between normal encryption without a pseudo- random data generator or steganography with or without random data.
- StegFS a steganographic file system for Linux. Doesn't only encrypt data like CFS/TCFS, also allows one to hide (parts of) data. Be aware that only using StegFS doesn't provide a secure hiding, additional precautions should be taken; see the FAQ on the site. Currently for Linux 2.2 only.