Steganography: The Art of Hidden Communication

Steganography is one of the oldest methods for hiding information from third parties. It was used as early as antiquity, primarily in the military and political spheres.

There are many different types of steganography:

• Double bottoms in packages or envelopes were used as secret hiding places.
• Messages were written with lemon juice as secret ink.
• Information was transformed into ciphertext through ciphers.
• Hidden messages in texts and images were sent as semagrams.

The only limit to steganography is creativity in transmitting information as securely as possible. Depending on the purpose, effort, and security level, different methods can be used and even combined.

Semagram and Coding

A well-known example of a semagram is the image of the San Antonio River from the book The Codebreakers – The Story of Secret Writing by David Kahn. In this case, secret messages were hidden in the image. The inconspicuous blades of grass on the bank are Morse code. A short and a long blade of grass in a tuft represent an "A" in this case. In this way, entire maps and other tactical information could be transmitted in the past.

The Morse Alphabet

Camouflage and Encryption Today

The need for secure data transmission has always existed – whether to communicate tactical decisions or agree on secret meeting points. Steganography is still used today, for example by criminals who hide malware in images.

However, those who wish to transmit confidential information are better off relying on recognized, secure methods today . Depending on the use case, symmetric or asymmetric encryption methods are used, for example AES, RSA or ECC. These methods secure internet communication, encrypted email traffic and also SIP telephone connections.