Hiding a secret message within an ordinary message and extracting it at the destination to maintain confidentiality of the data.
Example: Popular method is hiding a file inside an image or using image file as a cover.
- Substitution Techniques
- Transform Domain Techniques
- Cover Generation Techniques
- Spread Spectrum Techniques
- Distortion Techniques
- Statistical Techniques
Uses physical and chemical means to hide the existence of a message.Example – Invisible ink, Microdots, In Computers (Uses redundant information in pictures, text, sound etc)
Uses written natural language to hide the message in the carrier in some non-obvious ways.
- Semagrams – Uses visual symbols or signs. Further classified into visual(Eg Doodles) or Text semagrams (small changes in font size, color etc)
- Open codes – Hide in a specifically designed patter – unclear to the normal user.
- Jargon Code- Only a group of people can understand
- Covered Ciphers (Null Ciphers and Grille Cipher): Hidden openly in the carrier medium.