Codes and Ciphers :: Steganography

Steganography is the practice of hiding a message in a place where nobody would think to look. Generally, a steganographic message will appear to be something unassuming, like a picture, an article, a shopping list, or some other message. If you don't know where to look, you will not even know that a secret message has been hidden.

It may be hidden by using invisible ink between the visible lines of innocuous documents, or even written onto clothing. Another method simply pin pricking of individual letters in a newspaper article, thus forming a message. It may even be a few words written underneath a postage stamp.

The advantage of steganography over cryptography alone is that messages do not attract attention to themselves, to messengers, or to recipients. An unhidden coded message, no matter how unbreakable it is, will arouse suspicion and may in itself be incriminating.

• Invisible Ink
• Concealing messages within the lowest bits of a digital image.
• Chaffing and Winnowing - Sending multiple conflicting messages, where the recipient has some method of identifying the true message.
• Tattoo a message on someone's head and then let their hair grow back. Used in ancient Greece.
• Microdots - Text is written so small that a microscope is required to read it.

• Monoalphabetic Cipher
• Caesar Cipher
• Atbash Cipher
• Keyword Cipher
• Pigpen / Masonic Cipher
• Polybius Square
• Polyalphabetic Cipher
• Vigenère Cipher
• Beaufort Cipher
• Autokey Cipher
• Running Key Cipher

• Transposition Ciphers
• Rail Fence
• Route Cipher
• Columnar Transposition
• Polygraphic Substitution
• Playfair Cipher
• Bifid Cipher
• Trifid Cipher
• Four-square cipher

• Other Ciphers and Codes
• Book Cipher
• Beale Cipher
• Morse Code
• Tap Code
• One-time Pad
• Scytale
• Semaphore
• ASCII
• Steganography
• Techniques
• Frequency Analysis