0x11B into GF0x1B instead of 0x11BLinear algebra
MixColumn
Galois Multiplication lookup tables to speedup the Calculation
In [1]:
from math import floor
#import numpy as np
class aes:
def __init__(self,s_box):
self.s_box = s_box
def key_expension(self, key):
'''
todo...
'''
key_list = [key]*10
return key_list
def AddRoundKey(self, input_v,key):
output = list()
for a,b in zip(input_v,key):
output.append(a ^ b)
return output
def ByteSub(self, input_v):
for i in range(len(input_v)):
input_v[i] = self.s_box[input_v[i]]
def ShiftRow(input_v, c=4):
for i in range(floor(len(input_v)/c)):
j = i*c
a = input_v[j:j+c]
if(i>c):
raise ValueError('not N x N matrix')
input_v[j:j+c-i] = a[i:]
input_v[j+c-i:j+c] = a[:i]
def x2_gf(r):
'''
from https://en.wikipedia.org/wiki/Rijndael_MixColumns
'''
a=[]
b=[]
for c in range(0,4):
a[c] = r[c]
#/* h is 0xff if the high bit of r[c] is set, 0 otherwise */
h = r[c] >> 7 #/* arithmetic right shift, thus shifting in either zeros or ones */
b[c] = r[c] << 1 #/* implicitly removes high bit because b[c] is an 8-bit char, so we xor by 0x1b and not 0x11b in the next line */
b[c] = b[c] ^ 0x1B & h #/* Rijndael's Galois field */
return a,b
def MixColumn(self, input_v, c=4):
for i in range(floor(len(input_v)/c)):
a = list()
for i in range(floor(len(input_v)/c)):
a.append(input_v[i+c*j])
'''
get Galois Multiplication lookup tables for 2 times
'''
a,twotimes = self.x2_gf(a)
for i in range(floor(len(input_v)/c)):
input_v[i+c*j] = twotimes[i] ^ a[i+3 & 0x03] ^ a[i+2 & 0x03] ^ twotimes[i+1 & 0x03] ^ a[i+1 & 0x03] & 0xFF
def SBoxInit(self):
self.s_box = \
[0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67,
0x2b, 0xfe, 0xd7, 0xab, 0x76, 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59,
0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0, 0xb7,
0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1,
0x71, 0xd8, 0x31, 0x15, 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05,
0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75, 0x09, 0x83,
0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29,
0xe3, 0x2f, 0x84, 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b,
0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf, 0xd0, 0xef, 0xaa,
0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c,
0x9f, 0xa8, 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc,
0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2, 0xcd, 0x0c, 0x13, 0xec,
0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19,
0x73, 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee,
0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb, 0xe0, 0x32, 0x3a, 0x0a, 0x49,
0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4,
0xea, 0x65, 0x7a, 0xae, 0x08, 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6,
0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a, 0x70,
0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9,
0x86, 0xc1, 0x1d, 0x9e, 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e,
0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf, 0x8c, 0xa1,
0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0,
0x54, 0xbb, 0x16]
def encrypto(self, input_v, key):
i = 0
self.SBoxInit()
keys = self.key_expension(key)
output = copy(input_v)
for i in range(0,10):
output = self.AddRoundKey(output, keys[i])
self.ByteSub(output)
self.ShiftRow(output)
self.MixColumn(output)
self.ByteSub(output)
self.ShiftRow(output)
output = self.AddRoundKey(output, keys[i])
return output
In [2]:
# import
from Crypto.Cipher import AES
from Crypto import Random
from Crypto.Util import Counter
import codecs
import os
In [3]:
def decrypto(key,cipher,iv = Random.new().read(AES.block_size), mode=AES.MODE_CBC):
cipher = codecs.decode(cipher, 'hex')
if mode == AES.MODE_CTR:
ctr = Counter.new(AES.block_size*8,initial_value=int(iv,16))
decryptor = AES.new(key, mode, counter=ctr)
plain = decryptor.decrypt(cipher[AES.block_size:])
return plain
else:
decryptor = AES.new(key, mode, iv)
plain = decryptor.decrypt(cipher)
return plain[AES.block_size:]
In [4]:
CBC_key1 = codecs.decode('140b41b22a29beb4061bda66b6747e14', 'hex')
CBC_Ciphertext1 = '4ca00ff4c898d61e1edbf1800618fb2828a226d160dad07883d04e008a7897ee2e4b7465d5290d0c0e6c6822236e1daafb94ffe0c5da05d9476be028ad7c1d81'
iv = codecs.decode(CBC_Ciphertext1, 'hex')[:16]
decrypto(CBC_key1,CBC_Ciphertext1,iv)
Out[4]:
In [5]:
CBC_key2 = codecs.decode('140b41b22a29beb4061bda66b6747e14', 'hex')
CBC_Ciphertext2 = '5b68629feb8606f9a6667670b75b38a5b4832d0f26e1ab7da33249de7d4afc48e713ac646ace36e872ad5fb8a512428a6e21364b0c374df45503473c5242a253'
iv = codecs.decode(CBC_Ciphertext2, 'hex')[:16]
decrypto(CBC_key2,CBC_Ciphertext2,iv)
Out[5]:
In [6]:
CTR_key1 = codecs.decode('36f18357be4dbd77f050515c73fcf9f2', 'hex')
CTR_Ciphertext_1 = '69dda8455c7dd4254bf353b773304eec0ec7702330098ce7f7520d1cbbb20fc388d1b0adb5054dbd7370849dbf0b88d393f252e764f1f5f7ad97ef79d59ce29f5f51eeca32eabedd9afa9329'
iv = codecs.encode(codecs.decode(CTR_Ciphertext_1, 'hex')[:16],'hex')
decrypto(CTR_key1, CTR_Ciphertext_1, iv, mode=AES.MODE_CTR)
Out[6]:
In [7]:
CTR_Ciphertext_2 = '770b80259ec33beb2561358a9f2dc617e46218c0a53cbeca695ae45faa8952aa0e311bde9d4e01726d3184c34451'
iv = codecs.encode(codecs.decode(CTR_Ciphertext_2, 'hex')[:16],'hex')
decrypto(CTR_key1, CTR_Ciphertext_2, iv, mode=AES.MODE_CTR)
Out[7]: