How to take the least significant bit of a character and hide in an image file?

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the programme verifying whether a particular LSB has been modified, how to proceed?

c

  • It is a broad question, you should separate a code into specific parts and as it evolves, you can ask specific questions by placing the code you are developing, have some users who can help you if you follow this method... Consider doing a [tour] to check best practices when asking a question. Good Luck. I don’t know if this is what you’re looking for but I’ll leave you this tip : https://github.com/samuelcouch/c-steganography

  • I believe you can help, thank you!

1 answer

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You’re caught up in the concept of steganography. Let me try to explain a little here, and with that you should understand enough to start an implementation:

First, an image can be understood as a sequence of (height width) pixels, each of these being an integer number that encodes the clarity (in the case of a grayscale image) or the intensity of the red, green and blue components of each pixel.

Note that as there are many (at least 256) possible values for the intensity of each pixel (or each RGB component of each pixel), the difference between two neighboring values is very small, and virtually imperceptible when the pixel is rendered. So if that last least significant bit of pixel/component is zero or one, someone seeing the image won’t notice the difference. So you can hide a piece of data in those less meaningful bits without someone who doesn’t know what’s happening noticing.

Then take your message, and see it as a sequence of bits. For example, the string "Wikipedia\0" is seen as the sequence

0111 0111 0110 1001 0110 1011 0110 1001 0111 0000
0110 0101 0110 0100 0110 1001 0110 0001 0000 0000

(note the byte zero to mark the end of the message).

Then you take each of these 80 bits and hide, in order, in the less significant bits of the first 80 pixels (or the first 80 components) of your image.

See if you can understand well enough what you need to do so that you can ask other, more specific questions and post some code according to the rules of website.

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