Steganography Flashcards
What is steganography?
Information hiding used to send secret messages
What mediums can be used for steganography?
Text
Images
Audio
How are images constructed?
Stored in pixels, which represent light intensities.
8bit, 16bit or 24bits formats are commonly used.
Must store RGB values.
What type of image isn’t commonly used for Steganography?
JPEG due it being a lossy compression.
What type of images are commonly used for steganography?
BMP and GIF as they are lossless compression image files. This makes the replication more accurate on the receiving end.
What is the commonly used bit formats?
24bits but some use 256 colour grey-scale images as it’s harder to detect changes.
What images are used in steganography?
Two images, the message image and the cover image. These combine to create the stego-image.
What is LSB-n?
Least Significant Bit algorithm.
Change the LSB in order to encode secret messages into the image. Can change the number of bits used.
What’s the implication of using more bits for LSB-n?
The more bits that are used, the more likely the human eye will detect change. Studies show that this is at around 5 bits.
What images are better to use for Steganography?
Busier images, IE: crowds, so that changes are less likely to be detected.
Hard edges don’t work as changes can be seen along the edge, therefore fuzzier images are better.
What is Stego used for in the modern-day?
Used to get information passed to the outside of an organization while remaining hidden.
Also used to allow for secret messages to be passed between organizations. IE: Terrorism.
Why is it difficult to detect stego images?
It’s computationally difficult to find the hidden message as the n bits may change throughout - hard to also know when the answer is right without context.
