MATLAB: In a code of encryption if y=mod(x,256); is used. how can i apply the same statement in decryption process to get x back if i have only y and 256 know..

arnold transformcat mapencryptionunmod

encryption scheme i used was bit level permutation

Best Answer

You can't. If x is smaller than 256, the modulo operation replies x without changes. If x is larger than 256, this operation replies the remainder of the division, and the other information is lost. So if you do not store the value of floor(x / 256) anywhere, this "encryption" is not reversable in a unique manner.
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