![]() ![]() The only advantage of these algorithms are the simplicity of programming the algorithm and the fact that they’re immune to visual inspection of the picture.īy default, steganography is a type of security through obscurity, since it only hides the data - without encryption. In this manner, the data is hidden and never read by any photo-displaying program. ![]() ![]() Rather than hide the data in the photo by manipulating the picture, it instead appends the data to the end of the file as padding. Just about the worst of these algorithms is the class of append algorithms. Note that larger transformations (due to more embedded data) will make the manipulations more obvious. DCT algorithms are more subtle in the way they manipulate photos and so are harder to detect. It works by calculating the frequencies of the image and then replacing some of them. However, the more bits that are replaced, the more obvious the alterations will appear to both a statistical inspection and a visual inspection.įor this reason, there are lots of other steganography techniques, each with their own benefits and drawbacks.Īnother far less detectable one is called the discrete cosine transform (DCT) coefficient technique, which slightly changes the weights (coefficients) of the cosine waves that are used to reconstruct a JPEG image. The more bits replaced, the more bit depth is available, and the larger the image, the more data that can be stored in the photo. The LSB technique works well for media files, where slightly changing byte values creates only slight imperceptible changes, but things like ASCII text don’t fair so well, where a single bit out of place will completely change the character.Īlso, because it has an effect on the amount of a color, even if pretty small, replacing this bit with a bit from the hidden data will have the smallest effect on the picture possible. ![]() Each block of binary represents the value of the corresponding pixel. The diagram shows two four-pixel images in both color and binary values. ![]()
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