Cryptanalysis of the HillCipher
Usage: java Hillcipher knownCipherText knownClearText unknownCiphertext
This program finds the key using a known cipher text attack. Given a cipher text Ci and cleartext Cl we can obtain the key used to generate Ci through the operation:
key = inverse(Cl) * Ci
this key is then used to decrypt the file.
Currently the program needs the key size to be known to decrypt. It also cannot invert a non-square matrix.