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AES_key_sched.py
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AES_key_sched.py
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'''
* Author: Adnan Omar Khalaf Hleihel
* Created at: 19/12/2020
* Tile: AES implementation in python (Key Scheduling header)
'''
from random import seed, getrandbits
from AES_encrypt import subbytes
rcon = ((0x01, 0x00, 0x00, 0x00), (0x02, 0x00, 0x00, 0x00),
(0x04, 0x00, 0x00, 0x00), (0x08, 0x00, 0x00, 0x00),
(0x10, 0x00, 0x00, 0x00), (0x20, 0x00, 0x00, 0x00),
(0x40, 0x00, 0x00, 0x00), (0x80, 0x00, 0x00, 0x00),
(0x1B, 0x00, 0x00, 0x00), (0x36, 0x00, 0x00, 0x00));
key = bytearray(16)
round_key = []
def get_key(fn) :
global key
fp = open(fn, "rb")
key = bytearray(fp.read(16))
fp.close()
def gen_one_round_key(last, rnd) :
new = bytearray(16)
tmp = bytearray([last[13], last[14], last[15], last[12]])
subbytes(tmp, 4)
new[0] = last[0] ^ tmp[0] ^ rcon[rnd][0]
tmp[0] = new[0]
new[1] = last[1] ^ tmp[1] ^ rcon[rnd][1]
tmp[1] = new[1]
new[2] = last[2] ^ tmp[2] ^ rcon[rnd][2]
tmp[2] = new[2]
new[3] = last[3] ^ tmp[3] ^ rcon[rnd][3]
tmp[3] = new[3]
for i in range(4, 16, 4) :
new[i] = last[i] ^ tmp[0]
tmp[0] = new[i]
new[i+1] = last[i+1] ^ tmp[1]
tmp[1] = new[i+1]
new[i+2] = last[i+2] ^ tmp[2]
tmp[2] = new[i+2]
new[i+3] = last[i+3] ^ tmp[3]
tmp[3] = new[i+3]
return new
def gen_round_keys() :
global key
global round_key
round_key.append(gen_one_round_key(key, 0))
for i in range(9) :
round_key.append(gen_one_round_key(round_key[i], i+1))
def gen_random_key() :
global key
seed()
for i in range(16) :
key[i] = getrandbits(8)