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warlock415 t1_jbau2wr wrote

> Cryptographic hashes are a perfect test for this type of communication - the hash of the original will never match that of the altered copy

You're assuming you can access the original.

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volci t1_jbb8val wrote

someone can

The sender, for example

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warlock415 t1_jbbcbvr wrote

Not necessarily. Consider the following: I take a picture of my cat using a digital camera. I open up a laptop without a hard drive, boot to a Linux thumbdrive, copy over the picture from the camera's SD card. I make the picture smaller by some percentage amount and then make the picture bigger by the reciprocal. Save the output of that process and use that as the base for the steganography.

Now, even if someone gets their hands on that SD card and somehow defeats deleting the picture / destroying the card, they still don't have the "original" image that went into the steganography process.

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