steg

Steg, short for steganography, is the practice of concealing messages within ordinary data so that the very existence of the message is hidden. The term is from Greek steganos "covered" and graphia "writing"; the concept dates back to ancient and medieval concealment methods, and the word steganography was popularized in modern times by Johannes Trithemius in the late 15th century.

Digital steganography uses cover objects such as images, audio, video, text, or network traffic. A secret payload is embedded into the cover in a way that minimizes perceptible changes. The result is a stego object that looks normal while carrying hidden data. Common techniques include manipulating the least significant bits of media data, frequency-domain embedding, or more complex schemes that exploit redundancy and perceptual models. Text steganography might alter word choice or formatting; multimedia steganography exploits statistical properties.

Steganography has legitimate uses, such as digital watermarking, copyright protection, and privacy-preserving communications in sensitive environments. It also raises security concerns because it can enable covert channels for illicit activity. Because a stego object can conceal information, steganalysis—statistical or machine-learning based detection—seeks to identify hidden data and potentially extract it.

Compared to cryptography, steganography emphasizes concealment rather than transformation; many applications combine both. Trade-offs exist between payload capacity, detection risk, and robustness against manipulation like compression or resizing.