What Steganography Is

Steganography is the practice of concealing the very existence of a message by hiding it inside ordinary-looking data. The word comes from Greek steganos (covered) and graphein (writing) covered writing.

A secret might be hidden inside an image, an audio file, a document, or network traffic. To anyone who looks, the carrier appears completely normal an innocent vacation photo, a song, a PDF.

For security practitioners, steganography matters in two ways: defenders must understand how attackers use it to smuggle data, and analysts must know how to detect it.

These two are often confused but solve different problems:

• Cryptography hides the meaning of a message. An observer sees that a secret exists but cannot read it.
• Steganography hides the existence of a message. An observer does not even know a secret is present.

Cryptography protects content; steganography protects the fact of communication. An encrypted file draws attention it obviously contains something. A steganographic message hides in a file nobody suspects.