Decipher jpeg image

Questions
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1

Hi, I’m having trouble with a little test. I’ve been given a jpeg image which is cyphered with a XOR encryption. I have the key, which is the first 154193 (number of pixels) digits of pi. I’ve looked up the headers of the image and it appears that it was created with Wolfram Mathematica. How can I decypher the image now? I can link the image if you want (377x409 pixels)

2

I suspect you want ImageData to turn the imported picture into a matrix, Partition to break the key into a matrix the same dimensions as the data, and BitXor to decrypt each pixel.