The aim of this assignment is to perform a linear cryptanalysis of the FEAL-4 block cipher as presented in the lectures.
You can find a copy of the source code for this cipher (attached here)from which the secret key has been removed, but which also prints out the intermediate values of the cipher.
An executable version of this code which has the secret key built into it was used to generate the 200 random plaintexts/ciphertexts which can be found in the file [url removed, login to view] (attached here).
Your task is to discover as many of the bits as possible of the six 32-bit sub-keys K0-K5 used in this cipher. The more bits, the more marks you will get. However you will get some marks for even finding a few bits of the subkeys. You should submit your code along with a written report describing how you went about the cryptanalysis and the results obtained by email.
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