OutGuess
OutGuess by Niels Provos is a steganography tool that hides information in PNM or JPEG files.
OutGuess has been tested on OpenBSD, Linux, Solaris and AIX.
OutGuess preserves statistics based on frequency counts. As a result, statistical tests based on frequency counts are unable to detect the presence of steganographic content. Before embedding data into an image, OutGuess can determine the maximum message size that can be hidden while still being able to maintain statistics based on frequency counts.
OutGuess uses a generic iterator object to select which bits in the data should be modified. A seed can be used to modify the behavior of the iterator. It is embedded in the data along with the rest of the message. By altering the seed, OutGuess tries to find a sequence of bits that minimizes the number of changes in the data that have to be made.
Additionally, OutGuess allows to hide multiple messages (currently only 2) in the data. Thus, it also provides plausible deniablity. It keeps track of the bits that have been modified previously and locks them. A (23,12,7) Golay code is used for error correction to tolerate collisions on locked bits. Artificial errors are introduced to avoid modifying bits that have a hight bias.
Links
- Homepage
- Download v0.13b (different format)
- Fridrich, Goljan and Hogea's "Attacking the OutGuess" is capable of reliably detecting images with content embedded by OutGuess
- Higher-level statistical tests detect OutGuess 0.2
- Stegdetect - detects OutGuess 01.3b files
