def mix_cols(state):
mod = BitVector(bitstring='100011011')
bv2 = BitVector(hexstring='2')
bv3 = BitVector(hexstring='3')
for j in xrange(0, 4): # to select col
s0 = state[0][j]
s1 = state[1][j]
s2 = state[2][j]
s3 = state[3][j]
sp0 = bv2.gf_multiply_modular(s0, mod, 8) ^ bv3.gf_multiply_modular(s1, mod, 8) ^ s2 ^ s3
sp1 = s0 ^ bv2.gf_multiply_modular(s1, mod, 8) ^ bv3.gf_multiply_modular(s2, mod, 8) ^ s3
sp2 = s0 ^ s1 ^ bv2.gf_multiply_modular(s2, mod, 8) ^ bv3.gf_multiply_modular(s3, mod, 8)
sp3 = bv3.gf_multiply_modular(s0, mod, 8) ^ s1 ^ s2 ^ bv2.gf_multiply_modular(s3, mod, 8)
state[0][j] = sp0
state[1][j] = sp1
state[2][j] = sp2
state[3][j] = sp3
def mix_cols(state):
mod = BitVector(bitstring='100011011')
bv2 = BitVector(hexstring='2')
bv3 = BitVector(hexstring='3')
for j in xrange(0, 4): # to select col
s0 = state[0][j]
s1 = state[1][j]
s2 = state[2][j]
s3 = state[3][j]
sp0 = bv2.gf_multiply_modular(s0, mod, 8) ^ bv3.gf_multiply_modular(
s1, mod, 8) ^ s2 ^ s3
sp1 = s0 ^ bv2.gf_multiply_modular(
s1, mod, 8) ^ bv3.gf_multiply_modular(s2, mod, 8) ^ s3
sp2 = s0 ^ s1 ^ bv2.gf_multiply_modular(
s2, mod, 8) ^ bv3.gf_multiply_modular(s3, mod, 8)
sp3 = bv3.gf_multiply_modular(
s0, mod, 8) ^ s1 ^ s2 ^ bv2.gf_multiply_modular(s3, mod, 8)
state[0][j] = sp0
state[1][j] = sp1
state[2][j] = sp2
state[3][j] = sp3
else:
print(response.json())
##SOLUTION
modulus = BitVector(bitstring = '100011011')
n = 8
a = BitVector(bitstring = '11001001')
multi_inverse = a.gf_MI(modulus, n)
modulus = BitVector(bitstring='100011011') # AES modulus
n = 8
a = BitVector(bitstring='11001001')
b = BitVector(bitstring='11011001')
mult = a.gf_multiply_modular(b, modulus, n)
#You need to calculate c and a_inv
#c = a(x)*b(x)
#a_inv is inverse of a
c = mult
a_inv = multi_inverse
##END OF SOLUTION
#check result of part a
endpoint = '{}/{}/{}/{}'.format(API_URL, "mult", my_id, c)
response = requests.put(endpoint)
print(response.json())
def decrypt(inputfile, outputfile):
f = open('decrypted_hex.txt', 'a')
temp_shift = [0] * 4
key = get_encryption_key()
key_words = gen_key_schedule_128(key)
_, invSubBytesTable = genTables()
bv = BitVector(filename=inputfile)
statearray = [[0 for x in range(4)] for x in range(4)]
FILEOUT = open(outputfile, 'ab')
while bv.more_to_read:
bitvec = bv.read_bits_from_file(128)
if len(bitvec) > 0:
if len(bitvec) != 128:
bitvec.pad_from_right(128 - len(bitvec))
# Filling in statearray and XORing
for i in range(4):
for j in range(4):
statearray[i][j] = bitvec[32 * i + 8 * j:32 * i + 8 *
(j + 1)]
statearray[i][j] ^= key_words[-(4 - i)][8 * j:8 + (8 * j)]
for round_num in range(10, 0, -1):
# Inverse ShiftRows
for i in range(1, 4):
for j in range(0, 4):
temp_shift[(j + i) % 4] = statearray[j][i]
for j in range(0, 4):
statearray[j][i] = temp_shift[j]
# Inverse SubBytes
for i in range(4):
for j in range(4):
statearray[i][j] = BitVector(
intVal=invSubBytesTable[int(statearray[i][j])])
# Add round_num Key
for i in range(4):
for j in range(4):
statearray[i][j] ^= key_words[(4 * (round_num - 1)) +
i][8 * j:8 + (8 * j)]
# Inverse ColumnMixing
if round_num != 1:
zeroE = BitVector(bitstring='00001110')
zeroB = BitVector(bitstring='00001011')
zeroD = BitVector(bitstring='00001101')
zero9 = BitVector(bitstring='00001001')
for i in range(4):
temp = (zeroE.gf_multiply_modular(statearray[i][0], AES_modulus, 8)) ^ \
(zeroB.gf_multiply_modular(statearray[i][1], AES_modulus, 8)) ^ \
(zeroD.gf_multiply_modular(statearray[i][2], AES_modulus, 8)) ^ \
(zero9.gf_multiply_modular(statearray[i][3], AES_modulus, 8))
temp1 = (zeroE.gf_multiply_modular(statearray[i][1], AES_modulus, 8)) ^ \
(zeroB.gf_multiply_modular(statearray[i][2], AES_modulus, 8)) ^ \
(zeroD.gf_multiply_modular(statearray[i][3], AES_modulus, 8)) ^ \
(zero9.gf_multiply_modular(statearray[i][0], AES_modulus, 8))
temp2 = (zeroE.gf_multiply_modular(statearray[i][2], AES_modulus, 8)) ^ \
(zeroB.gf_multiply_modular(statearray[i][3], AES_modulus, 8)) ^ \
(zeroD.gf_multiply_modular(statearray[i][0], AES_modulus, 8)) ^ \
(zero9.gf_multiply_modular(statearray[i][1], AES_modulus, 8))
temp3 = (zeroE.gf_multiply_modular(statearray[i][3], AES_modulus, 8)) ^ \
(zeroB.gf_multiply_modular(statearray[i][0], AES_modulus, 8)) ^ \
(zeroD.gf_multiply_modular(statearray[i][1], AES_modulus, 8)) ^ \
(zero9.gf_multiply_modular(statearray[i][2], AES_modulus, 8))
statearray[i][0] = temp
statearray[i][1] = temp1
statearray[i][2] = temp2
statearray[i][3] = temp3
for i in range(4):
for j in range(4):
statearray[i][j].write_to_file(FILEOUT)
f.write(statearray[i][j].get_bitvector_in_hex())
f.close()
FILEOUT.close()
return
def encrypt(inputfile, outputfile):
f = open('encrypted_hex.txt', 'a')
key = get_encryption_key()
key_words = gen_key_schedule_128(key)
subBytesTable, _ = genTables()
bv = BitVector(filename=inputfile)
statearray = [[0 for x in range(4)] for x in range(4)]
FILEOUT = open(outputfile, 'ab')
temp_shift = [0] * 4
while bv.more_to_read:
bitvec = bv.read_bits_from_file(128)
if len(bitvec) > 0:
if len(bitvec) != 128:
bitvec.pad_from_right(128 - len(bitvec))
# Filling in statearray and XORing
for i in range(4):
for j in range(4):
statearray[i][j] = bitvec[32 * i + 8 * j:32 * i + 8 *
(j + 1)]
statearray[i][j] ^= key_words[i][8 * j:8 + (8 * j)]
for round_num in range(10):
# SubBytes
for i in range(4):
for j in range(4):
statearray[i][j] = BitVector(
intVal=subBytesTable[int(statearray[i][j])])
# ShiftRows
for i in range(1, 4):
for j in range(0, 4):
temp_shift[(j - i) % 4] = statearray[j][i]
for j in range(0, 4):
statearray[j][i] = temp_shift[j]
# ColumnMixing
if round_num != 9:
two_times = BitVector(bitstring='00000010')
three_times = BitVector(bitstring='00000011')
for i in range(4):
temp = (two_times.gf_multiply_modular(statearray[i][0], AES_modulus, 8)) ^ \
(three_times.gf_multiply_modular(statearray[i][1], AES_modulus, 8)) ^ \
statearray[i][2] ^ \
statearray[i][3]
temp1 = (two_times.gf_multiply_modular(statearray[i][1], AES_modulus, 8)) ^ \
(three_times.gf_multiply_modular(statearray[i][2], AES_modulus, 8)) ^ \
statearray[i][3] ^ \
statearray[i][0]
temp2 = (two_times.gf_multiply_modular(statearray[i][2], AES_modulus, 8)) ^ \
(three_times.gf_multiply_modular(statearray[i][3], AES_modulus, 8)) ^ \
statearray[i][0] ^ \
statearray[i][1]
temp3 = (two_times.gf_multiply_modular(statearray[i][3], AES_modulus, 8)) ^ \
(three_times.gf_multiply_modular(statearray[i][0], AES_modulus, 8)) ^ \
statearray[i][1] ^ \
statearray[i][2]
statearray[i][0] = temp
statearray[i][1] = temp1
statearray[i][2] = temp2
statearray[i][3] = temp3
# Add round_num Key
for i in range(4):
for j in range(4):
statearray[i][j] ^= key_words[(4 * (round_num + 1)) +
i][8 * j:8 + (8 * j)]
for i in range(4):
for j in range(4):
statearray[i][j].write_to_file(FILEOUT)
f.write(statearray[i][j].get_bitvector_in_hex())
f.close()
FILEOUT.close()
return
