Steganography Flashcards
What is steganography?
The art/science of communicating by hiding secret messages in innocuous ‘cover’ objects (such as an image).
What is an acrostic?
A text, usually a poem, in which particular letters, such as the first letters of each line, spell a word or phrase.
What is a cover object (C)?
A message that can be transmitted without suspicion.
What is a stego-object (S)?
A cover object containing an embedded secret object.
What is a stego-key (k)?
Used to encrypt the secret message
What are the two types of steganography and which is more secure?
- Pure
- Stego-key
- Stego-key is more secure
What is pure steganography?
- Does not require the exchange of prior information such as a stego-key
- Both sender and receiver must have access to the embedding and extraction algorithm but the algorithm should not be public.
When is a stego-key exchanged?
A secret stego-key is exchanged prior to communicating using a stego-object.
What is LSB?
Least significant bit
What is a visual attack?
A visual attack is a means of detecting embedded information e.g. by visual inspection of the least significant bits only of a digital image.
What happens to an image where embedding takes place?
In general image structure is lost when embedding has taken place
What do visual attacks work well for and what can it tell you?
- Can also tell us the proportion of the image that has been used for embedding.
- Can work well for sequential embedding
What do visual attacks not work well for?
Random interval method
What do statistical attacks refer to?
The term statistical attack is used when referring to non-visual methods for determining embedding.
What changes an image histogram?
Embedding secret information in the least significant bits of an image changes the image histogram.
