Image and Key XORing
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Hi there i am still stuck in xoring a 256 byte value with an image stored in a 3D array ? what should be the steps to do it ?I want to the store the first 256 bytes of the image and xor it with key then another 25 bytes of image with the same key and so on .I would later display my results in a figure ?
Any help would be greatly appreciated .
thanks
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Walter Roberson
le 8 Fév 2012
Untested:
t = reshape(YourImage(:), 256, []);
EncryptedImage = reshape( bsxfun(@xor, t, YourKey(:).'), size(YourImage) );
Of course you might have a rather different idea of what the "first" 256 bytes of an image are...
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Walter Roberson
le 8 Fév 2012
Correct. Your question did say what to do if your image was not divisible in to 256 byte groups, so I did not code for it.
xc = x(:);
nel = size(xc,1);
npad = mod(256 - mod(nel,256), 256);
xc = vertcat(xc, zeros(npad, 1));
t = reshape(xc, 256, []);
enct = bsxfun(@xor, t, YourKey(:).');
enct(end-npad+1:end) = [];
EncryptedImage = reshape( enct, size(x));
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