Stegs

Stegs is short for steganography, the practice of concealing messages within ordinary files so that the existence of the message is hidden. Unlike cryptography, which aims to make a message unreadable, steganography aims to conceal that a message even exists. It can be used for covert communication, watermarking, or data integrity purposes.

Common carriers include digital images, audio, video, text, and even network protocols. The payload is embedded with changes that aim to be imperceptible or hard to detect. In images, techniques such as least significant bit substitution modify the least significant bits of pixels; in the transform domain, methods operate on frequency coefficients. Audio can use methods like echo hiding or phase coding. Text-based steganography might rely on whitespace or formatting, while some protocols encode data in header fields or timing.

Practical steganography relies on tools that embed and extract hidden data. Examples of steganography tools include Steghide, OpenStego, and SilentEye, often with optional encryption of the payload. The amount of data that can be hidden (the capacity) and its detectability depend on the carrier and method used, as well as any compression or processing the file undergoes.

Steganalysis is the field that seeks to detect concealed data, using statistical analysis, pattern recognition, and sometimes machine learning. Detecting steganography is challenging and not always reliable. Watermarking, a related practice, embeds information to assert ownership or track distribution while attempting to remain robust against manipulation.

Ethical and legal issues surround steganography. It can be used for legitimate privacy or copyright protection, but it also enables covert communication and illicit activity. Users should be aware of applicable laws and the risk of data loss or exposure when embedding data in shared files.