6 - Steganography and Watermarking Flashcards
Desired properties of steganography
Imperceptibility
Security
Capacity
Exploiting the image format
Insert secrets after EOF f.ex or in the least significant bits
Adding a key protection
Shifting or use a random interval to spread the secret message
Steganography techniques
Substitution methods
Transform method techniques
Distortion techniques
Cover generation methods
Types of steganalysis
Targeted
Blind
Structural detection
method based on inspection of file properties/contents
Statistical detection
using histograms to see repetitive trends
Visual detection
detecting by viewing it
Watermarking
Imperceptible
Inseparable from the work its embedded it
Remains embedded even during transformation
Can be visible or invisible
Robustness is the main issue
Steganography
Capacity desired for message is large
Always invisible
Dependent on file format
Checksum embedding
Recover the watermark by applying a checksum function to each pixel of auth image and check LSBs
Watermarking attacking methods
Removal attacks - remove watermark completely
Geometrical attacks - distort watermark
Cryptographic attacks - aim at cracking the security methods
Protocol attacks - aim at cracking the algorithms
Difficulties associated with watermarks for investigators
They cant be detected
False watermarks can be detected
Unauthorized detection of the watermarks
