hill-cipher.py

#!/usr/bin/env python
# encoding: utf-8

import numpy as np

def twist(data, size):
    matrix = []
    for i in range(0, len(data), size):
        d = []
        for j in range(size):
            d.append(ord(data[i + j]) - ord('a'))
        matrix.append(d)
    return np.asarray(matrix).T

def untwist(data, size):
    result = ""
    for line in data.T:
        for i in line:
            result += chr(int(round(i)) % 26 + ord('a'))
    return result


def encrypt(plain, key):
    print "Enc: "
    print "Key: %s" % (key)
    matrix = twist(plain, len(key))
    print "Plain: %s" % (matrix)
    cipher = np.dot(key, matrix)
    print "Cipher: %s" % (cipher)
    return cipher
    return untwist(cipher, len(key))

def Encrypt(plain, key):
    print "Enc: "
    print "Key: %s" % (key)
    # matrix = twist(plain, len(key))
    matrix = plain
    print "Plain: %s" % (matrix)
    cipher = np.dot(key, matrix)
    print "Cipher: %s" % (cipher)
    return cipher
    # return untwist(cipher, len(key))



def decrypt(cipher, key):
    print "Dec: "
    yek = np.linalg.inv(key)
    print "Key: %s" % (yek)
    matrix = twist(cipher, len(key))
    print "Cipher: %s" % (matrix)
    plain = np.dot(yek, matrix)
    print "Plain: %s" % (plain)
    return untwist(plain, len(key))

def Decrypt(cipher, key):
    print "Dec: "
    yek = np.linalg.inv(key)
    print "Key: %s" % (yek)
    # matrix = twist(cipher, len(key))
    matrix = cipher
    print "Cipher: %s" % (matrix)
    plain = np.dot(yek, matrix)
    print "Plain: %s" % (plain)
    return plain
    # return untwist(plain, len(key))


key = np.asarray([[6, 24, 17], [13, 15, 10], [20, 16, 1]])
key = np.asarray([[5, 23, 16], [12, 14, 9], [19, 15, 0]])


'''
qbuquagnmfzbtbtaambub
fxqmojtpa
'''

plain = [
    [0, 3, 5, 8],
    [0, 8, 1, 3],
    [0, 24, 2, 3],
]

cipher = Encrypt(plain, key)
print cipher

plain = Decrypt(cipher, key)
print plain