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#!/usr/bin/python
from pprint import pprint
from constants import round_constants
from constants import sbox
matrix_size = 4
def hex_to_matrix(hex_array):
matrix = []
for i in range(16):
if i % matrix_size == 0:
matrix.append([hex_array[i]])
else:
matrix[int(i / 4)].append(hex_array[i])
return matrix
def text_to_hex(text):
hex_array = []
for char in text:
hex_array.append(ord(char))
return hex_array
def shift_matrix(matrix):
for i in range(matrix_size):
matrix[i] = matrix[i][-i:] + matrix[i][:-i]
return matrix
def key_expansion(key_matrix):
round_keys = [key_matrix]
round_key = key_matrix[:]
for r in range(0, 10):
new_key = round_key.copy()
last = round_key[3]
new_key[3] = round_last(new_key[3], r)
new_key[0] = xor_matrix(new_key[0], new_key[3])
new_key[1] = xor_matrix(new_key[1], new_key[0])
new_key[2] = xor_matrix(new_key[2], new_key[1])
new_key[3] = xor_matrix(last, new_key[2])
round_key = new_key
round_keys += [new_key]
return round_keys
def xor_matrix(first, second):
first = first.copy()
for i in range(4):
first[i] = first[i] ^ second[i]
return first
def round_last(round_key, r):
# Shift bottom row
last_column = round_key[1:] + round_key[:1]
# Byte substitution (sbox uses hex representation as index)
for column in range(matrix_size):
last_column[column] = sbox[last_column[column]]
# Adding round constant
last_column[0] = last_column[0] ^ round_constants[r]
return last_column
test_key = text_to_hex("Thats my Kung Fu")
test_text = text_to_hex("Two One Nine Two")
pprint(hex_to_matrix(test_key))
print("\n\n")
pprint(key_expansion(hex_to_matrix(test_key)))
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