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py-kms/py3-kms/aes.py

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py3-kms upload
2018-02-28 23:27:12 +01:00
#!/usr/bin/env python3
# aes.py: implements AES - Advanced Encryption Standard
# from the SlowAES project, http://code.google.com/p/slowaes/
#
# Copyright (c) 2008 Josh Davis ( http://www.josh-davis.org ), Alex Martelli ( http://www.aleax.it )
#
# Ported from C code written by Laurent Haan ( http://www.progressive-coding.com )
# Licensed under the Apache License, Version 2.0
# http://www.apache.org/licenses/
#
"""
Ported to Python3 with minimal changements.
© Copyright 2018 Matteo ℱan <SystemRage@protonmail.com>
"""
import os
import math
def append_PKCS7_padding(val):
""" Function to pad the given data to a multiple of 16-bytes by PKCS7 padding. """
numpads = 16 - (len(val) % 16)
return val + numpads * bytes(chr(numpads), 'utf-8')
def strip_PKCS7_padding(val):
""" Function to strip off PKCS7 padding. """
if len(val) % 16 or not val:
raise ValueError("String of len %d can't be PCKS7-padded" % len(val))
numpads = val[-1]
if numpads > 16:
raise ValueError("String ending with %r can't be PCKS7-padded" % val[-1])
return val[:-numpads]
class AES( object ):
""" Class implementing the Advanced Encryption Standard algorithm. """
#*py-kms*
v6 = False
# Valid key sizes
KeySize = {
"SIZE_128": 16,
"SIZE_192": 24,
"SIZE_256": 32
}
# Rijndael S-box
sbox = [ 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 ]
# Rijndael Inverted S-box
rsbox = [ 0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3,
0x9e, 0x81, 0xf3, 0xd7, 0xfb, 0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f,
0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb, 0x54,
0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b,
0x42, 0xfa, 0xc3, 0x4e, 0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24,
0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25, 0x72, 0xf8,
0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d,
0x65, 0xb6, 0x92, 0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda,
0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84, 0x90, 0xd8, 0xab,
0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3,
0x45, 0x06, 0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1,
0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b, 0x3a, 0x91, 0x11, 0x41,
0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6,
0x73, 0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9,
0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e, 0x47, 0xf1, 0x1a, 0x71, 0x1d,
0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0,
0xfe, 0x78, 0xcd, 0x5a, 0xf4, 0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07,
0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f, 0x60,
0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f,
0x93, 0xc9, 0x9c, 0xef, 0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5,
0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61, 0x17, 0x2b,
0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55,
0x21, 0x0c, 0x7d ]
# Rijndael Rcon
Rcon = [ 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36,
0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97,
0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72,
0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66,
0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04,
0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d,
0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3,
0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61,
0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a,
0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40,
0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc,
0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5,
0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a,
0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d,
0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c,
0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35,
0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4,
0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc,
0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08,
0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a,
0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d,
0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2,
0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74,
0xe8, 0xcb ]
def getSBoxValue(self,num):
""" Method to retrieve a given S-Box value. """
return self.sbox[num]
def getSBoxInvert(self,num):
""" Method to retrieve a given Inverted S-Box value."""
return self.rsbox[num]
def rotate(self, word):
""" Method performing Rijndael's key schedule rotate operation.
Rotate a word eight bits to the left: eg, rotate(1d2c3a4f) == 2c3a4f1d
@param word: char list of size 4 (32 bits overall).
"""
return word[1:] + word[:1]
def getRconValue(self, num):
""" Method to retrieve a given Rcon value. """
return self.Rcon[num]
def core(self, word, iteration):
""" Method performing the key schedule core operation. """
# Rotate the 32-bit word 8 bits to the left.
word = self.rotate(word)
# Apply S-Box substitution on all 4 parts of the 32-bit word.
for i in range(4):
word[i] = self.getSBoxValue(word[i])
# XOR the output of the rcon operation with i to the first part (leftmost) only.
word[0] = word[0] ^ self.getRconValue(iteration)
return word
def expandKey(self, key, size, expandedKeySize):
""" Method performing Rijndael's key expansion.
Expands an 128, 192, 256 key into an 176, 208, 240 bit key.
"""
# Current expanded keySize, in bytes.
currentSize = 0
rconIteration = 1
expandedKey = [0] * expandedKeySize
# Set the 16, 24, 32 bytes of the expanded key to the input key.
for j in range(size):
expandedKey[j] = key[j]
currentSize += size
while currentSize < expandedKeySize:
# Assign the previous 4 bytes to the temporary value t.
t = expandedKey[currentSize - 4:currentSize]
# Every 16,24,32 bytes we apply the core schedule to t
# and increment rconIteration afterwards.
if currentSize % size == 0:
t = self.core(t, rconIteration)
rconIteration += 1
# For 256-bit keys, we add an extra sbox to the calculation.
if size == self.KeySize["SIZE_256"] and ((currentSize % size) == 16):
for l in range(4):
t[l] = self.getSBoxValue(t[l])
# We XOR t with the four-byte block 16,24,32 bytes before the new
# expanded key. This becomes the next four bytes in the expanded key.
for m in range(4):
expandedKey[currentSize] = expandedKey[currentSize - size] ^ t[m]
currentSize += 1
return expandedKey
def addRoundKey(self, state, roundKey):
""" Method to add (XORs) the round key to the state. """
for i in range(16):
state[i] ^= roundKey[i]
return state
def createRoundKey(self, expandedKey, roundKeyPointer):
""" Creates a round key from the given expanded key and the
position within the expanded key.
"""
roundKey = [0] * 16
for i in range(4):
for j in range(4):
roundKey[j * 4 + i] = expandedKey[roundKeyPointer + i * 4 + j]
return roundKey
def galois_multiplication(self, a, b):
""" Method to perform a Galois multiplication of 8 bit characters
a and b.
"""
p = 0
for counter in range(8):
if b & 1:
p ^= a
hi_bit_set = a & 0x80
a <<= 1
# keep a 8 bit
a &= 0xFF
if hi_bit_set:
a ^= 0x1b
b >>= 1
return p
def subBytes(self, state, isInv):
""" Method to substitute all the values from the state with the
value in the SBox using the state value as index for the SBox.
"""
if isInv:
getter = self.getSBoxInvert
else:
getter = self.getSBoxValue
for i in range(16):
state[i] = getter(state[i])
return state
def shiftRows(self, state, isInv):
""" Method to iterate over the 4 rows and call shiftRow(...) with that row. """
for i in range(4):
state = self.shiftRow(state, i * 4, i, isInv)
return state
def shiftRow(self, state, statePointer, nbr, isInv):
""" Method to shift the row to the left. """
for i in range(nbr):
if isInv:
state[statePointer:statePointer + 4] = state[statePointer + 3:statePointer + 4] + \
state[statePointer:statePointer + 3]
else:
state[statePointer:statePointer + 4] = state[statePointer + 1:statePointer + 4] + \
state[statePointer:statePointer + 1]
return state
def mixColumns(self, state, isInv):
""" Method to perform a galois multiplication of the 4x4 matrix. """
# Iterate over the 4 columns.
for i in range(4):
# Construct one column by slicing over the 4 rows.
column = state[i:i + 16:4]
# Apply the mixColumn on one column.
column = self.mixColumn(column, isInv)
# Put the values back into the state.
state[i:i + 16:4] = column
return state
def mixColumn(self, column, isInv):
""" Method to perform a galois multiplication of 1 column the 4x4 matrix. """
if isInv:
mult = [14, 9, 13, 11]
else:
mult = [2, 1, 1, 3]
cpy = list(column)
g = self.galois_multiplication
column[0] = g(cpy[0], mult[0]) ^ g(cpy[3], mult[1]) ^ \
g(cpy[2], mult[2]) ^ g(cpy[1], mult[3])
column[1] = g(cpy[1], mult[0]) ^ g(cpy[0], mult[1]) ^ \
g(cpy[3], mult[2]) ^ g(cpy[2], mult[3])
column[2] = g(cpy[2], mult[0]) ^ g(cpy[1], mult[1]) ^ \
g(cpy[0], mult[2]) ^ g(cpy[3], mult[3])
column[3] = g(cpy[3], mult[0]) ^ g(cpy[2], mult[1]) ^ \
g(cpy[1], mult[2]) ^ g(cpy[0], mult[3])
return column
def aes_round(self, state, roundKey, roundKms):
""" Method to apply the 4 operations of the forward round in sequence. """
state = self.subBytes(state, False)
state = self.shiftRows(state, False)
state = self.mixColumns(state, False)
#*py-kms*
if self.v6:
if roundKms == 4:
state[0] ^= 0x73
if roundKms == 6:
state[0] ^= 0x09
if roundKms == 8:
state[0] ^= 0xE4
state = self.addRoundKey(state, roundKey)
return state
def aes_invRound(self, state, roundKey, roundKms):
""" Method to apply the 4 operations of the inverse round in sequence. """
state = self.shiftRows(state, True)
state = self.subBytes(state, True)
state = self.addRoundKey(state, roundKey)
#*py-kms*
if self.v6:
if roundKms == 4:
state[0] ^= 0x73
if roundKms == 6:
state[0] ^= 0x09
if roundKms == 8:
state[0] ^= 0xE4
state = self.mixColumns(state, True)
return state
def aes_main(self, state, expandedKey, nbrRounds):
""" Method to do the AES encryption for one round.
Perform the initial operations, the standard round and the
final operations of the forward AES, creating a round key for each round.
"""
state = self.addRoundKey(state, self.createRoundKey(expandedKey, 0))
i = 1
while i < nbrRounds:
state = self.aes_round(state, self.createRoundKey(expandedKey, 16 * i), i)
i += 1
state = self.subBytes(state, False)
state = self.shiftRows(state, False)
state = self.addRoundKey(state, self.createRoundKey(expandedKey, 16 * nbrRounds))
return state
def aes_invMain(self, state, expandedKey, nbrRounds):
""" Method to do the inverse AES encryption for one round.
Perform the initial operations, the standard round, and the
final operations of the inverse AES, creating a round key for each round.
"""
state = self.addRoundKey(state, self.createRoundKey(expandedKey, 16 * nbrRounds))
i = nbrRounds - 1
while i > 0:
state = self.aes_invRound(state, self.createRoundKey(expandedKey, 16 * i), i)
i -= 1
state = self.shiftRows(state, True)
state = self.subBytes(state, True)
state = self.addRoundKey(state, self.createRoundKey(expandedKey, 0))
return state
def encrypt(self, iput, key, size):
""" Method to encrypt a 128 bit input block against the given key
of size specified.
"""
output = [0] * 16
# The number of rounds.
nbrRounds = 0
# The 128 bit block to encode.
block = [0] * 16
# Set the number of rounds.
if size == self.KeySize["SIZE_128"]:
nbrRounds = 10
elif size == self.KeySize["SIZE_192"]:
nbrRounds = 12
elif size == self.KeySize["SIZE_256"]:
nbrRounds = 14
# *py-kms* The KMS v4 parameters.
elif size == 20:
nbrRounds = 11
else:
raise ValueError("Wrong key size given ({}).".format(size))
# The expanded keySize.
expandedKeySize = 16 * (nbrRounds + 1)
# Set the block values, for the block:
# a[0,0] a[0,1] a[0,2] a[0,3]
# a[1,0] a[1,1] a[1,2] a[1,3]
# a[2,0] a[2,1] a[2,2] a[2,3]
# a[3,0] a[3,1] a[3,2] a[3,3]
# the mapping order is a[0,0] a[1,0] a[2,0] a[3,0] a[0,1] a[1,1] ... a[2,3] a[3,3]
# Iterate over the columns and over the rows.
for i in range(4):
for j in range(4):
block[i + j * 4] = iput[i * 4 +j]
# Expand the key into an 176, 208, 240 bit key
expandedKey = self.expandKey(key, size, expandedKeySize)
# Encrypt the block using the expandedKey.
block = self.aes_main(block, expandedKey, nbrRounds)
# Unmap the block again into the output.
for k in range(4):
for l in range(4):
output[k * 4 + l] = block[k + l * 4]
return output
def decrypt(self, iput, key, size):
""" Method to decrypt a 128 bit input block against the given key
of size specified.
"""
output = [0] * 16
# The number of rounds.
nbrRounds = 0
# The 128 bit block to decode.
block = [0] * 16
# Set the number of rounds.
if size == self.KeySize["SIZE_128"]:
nbrRounds = 10
elif size == self.KeySize["SIZE_192"]:
nbrRounds = 12
elif size == self.KeySize["SIZE_256"]:
nbrRounds = 14
#*py-kms* The KMS v4 parameters.
elif size == 20:
nbrRounds = 11
else:
raise ValueError("Wrong key size given ({}).".format(size))
# The expanded keySize.
expandedKeySize = 16 * (nbrRounds + 1)
# Set the block values, for the block:
# a[0,0] a[0,1] a[0,2] a[0,3]
# a[1,0] a[1,1] a[1,2] a[1,3]
# a[2,0] a[2,1] a[2,2] a[2,3]
# a[3,0] a[3,1] a[3,2] a[3,3]
# the mapping order is a[0,0] a[1,0] a[2,0] a[3,0] a[0,1] a[1,1] ... a[2,3] a[3,3]
# Iterate over the columns and the rows.
for i in range(4):
for j in range(4):
block[i + j * 4] = iput[i * 4 + j]
# Expand the key into an 176, 208, 240 bit key.
expandedKey = self.expandKey(key, size, expandedKeySize)
# Decrypt the block using the expandedKey.
block = self.aes_invMain(block, expandedKey, nbrRounds)
# Unmap the block again into the output.
for k in range(4):
for l in range(4):
output[k * 4 +l] = block[k + l * 4]
return output
class AESModeOfOperation( object ):
""" Class implementing the different AES mode of operations. """
aes = AES()
# Supported modes of operation.
ModeOfOperation = {
"OFB": 0,
"CFB": 1,
"CBC": 2
}
def convertString(self, string, start, end, mode):
""" Method to convert a 16 character string into a number array. """
if end - start > 16:
end = start + 16
if mode == self.ModeOfOperation["CBC"]:
ar = [0] * 16
else:
ar = []
i = start
j = 0
while len(ar) < end - start:
ar.append(0)
while i < end:
ar[j] = string[i]
j += 1
i += 1
return ar
def encrypt(self, stringIn, mode, key, size, IV):
""" Method to perform the encryption operation.
@param stringIn: input string to be encrypted
@param mode: mode of operation (0, 1 or 2)
@param key: a hex key of the bit length size
@param size: the bit length of the key (16, 24 or 32)
@param IV: the 128 bit hex initilization vector
@return tuple with mode of operation, length of the input and the encrypted data
"""
if len(key) % size:
raise ValueError("Illegal size ({}) for key '{}'.".format(size, key))
if len(IV) % 16:
raise ValueError("IV is not a multiple of 16.")
# The AES input/output.
plaintext = []
iput = [0] * 16
output = []
ciphertext = [0] * 16
# The output cipher string.
cipherOut = []
firstRound = True
if stringIn != None:
for j in range(int(math.ceil(float(len(stringIn))/16))):
start = j * 16
end = j * 16 + 16
if end > len(stringIn):
end = len(stringIn)
plaintext = self.convertString(stringIn, start, end, mode)
if mode == self.ModeOfOperation["CFB"]:
if firstRound:
output = self.aes.encrypt(IV, key, size)
firstRound = False
else:
output = self.aes.encrypt(iput, key, size)
for i in range(16):
if len(plaintext) - 1 < i:
ciphertext[i] = 0 ^ output[i]
elif len(output) - 1 < i:
ciphertext[i] = plaintext[i] ^ 0
elif len(plaintext) - 1 < i and len(output) < i:
ciphertext[i] = 0 ^ 0
else:
ciphertext[i] = plaintext[i] ^ output[i]
for k in range(end - start):
cipherOut.append(ciphertext[k])
iput = ciphertext
elif mode == self.ModeOfOperation["OFB"]:
if firstRound:
output = self.aes.encrypt(IV, key, size)
firstRound = False
else:
output = self.aes.encrypt(iput, key, size)
for i in range(16):
if len(plaintext) - 1 < i:
ciphertext[i] = 0 ^ output[i]
elif len(output) - 1 < i:
ciphertext[i] = plaintext[i] ^ 0
elif len(plaintext) - 1 < i and len(output) < i:
ciphertext[i] = 0 ^ 0
else:
ciphertext[i] = plaintext[i] ^ output[i]
for k in range(end - start):
cipherOut.append(ciphertext[k])
iput = output
elif mode == self.ModeOfOperation["CBC"]:
for i in range(16):
if firstRound:
iput[i] = plaintext[i] ^ IV[i]
else:
iput[i] = plaintext[i] ^ ciphertext[i]
firstRound = False
ciphertext = self.aes.encrypt(iput, key, size)
# Always 16 bytes because of the padding for CBC.
for k in range(16):
cipherOut.append(ciphertext[k])
return mode, len(stringIn), cipherOut
def decrypt(self, cipherIn, originalsize, mode, key, size, IV):
""" Method to perform the decryption operation.
@param cipherIn: encrypted string to be decrypted
@param originalsize: unencrypted string length (required for CBC)
@param mode: mode of operation (0, 1 or 2)
@param key: a number array of the bit length size
@param size: the bit length of the key (16, 24 or 32)
@param IV: the 128 bit number array initilization vector
@return decrypted data
"""
if len(key) % size:
raise ValueError("Illegal size ({}) for key '{}'.".format(size, key))
if len(IV) % 16:
raise ValueError("IV is not a multiple of 16.")
# The AES input/output.
ciphertext = []
iput = []
output = []
plaintext = [0] * 16
# The output plain text character list.
chrOut = []
firstRound = True
if cipherIn != None:
for j in range(int(math.ceil(float(len(cipherIn))/16))):
start = j * 16
end = j * 16 + 16
if j * 16 + 16 > len(cipherIn):
end = len(cipherIn)
ciphertext = cipherIn[start:end]
if mode == self.ModeOfOperation["CFB"]:
if firstRound:
output = self.aes.encrypt(IV, key, size)
firstRound = False
else:
output = self.aes.encrypt(iput, key, size)
for i in range(16):
if len(output) - 1 < i:
plaintext[i] = 0 ^ ciphertext[i]
elif len(ciphertext) - 1 < i:
plaintext[i] = output[i] ^ 0
elif len(output) - 1 < i and len(ciphertext) < i:
plaintext[i] = 0 ^ 0
else:
plaintext[i] = output[i] ^ ciphertext[i]
for k in range(end - start):
chrOut.append(plaintext[k])
iput = ciphertext
elif mode == self.ModeOfOperation["OFB"]:
if firstRound:
output = self.aes.encrypt(IV, key, size)
firstRound = False
else:
output = self.aes.encrypt(iput, key, size)
for i in range(16):
if len(output) - 1 < i:
plaintext[i] = 0 ^ ciphertext[i]
elif len(ciphertext) - 1 < i:
plaintext[i] = output[i] ^ 0
elif len(output) - 1 < i and len(ciphertext) < i:
plaintext[i] = 0 ^ 0
else:
plaintext[i] = output[i] ^ ciphertext[i]
for k in range(end - start):
chrOut.append(plaintext[k])
iput = output
elif mode == self.ModeOfOperation["CBC"]:
output = self.aes.decrypt(ciphertext, key, size)
for i in range(16):
if firstRound:
plaintext[i] = IV[i] ^ output[i]
else:
plaintext[i] = iput[i] ^ output[i]
firstRound = False
if originalsize is not None and originalsize < end:
for k in range(originalsize - start):
chrOut.append(plaintext[k])
else:
for k in range(end - start):
chrOut.append(plaintext[k])
iput = ciphertext
return chrOut
def encryptData(key, data, mode=AESModeOfOperation.ModeOfOperation["CBC"]):
""" Module function to encrypt the given data with the given key.
@param key: key to be used for encryption
@param data: data to be encrypted
@param mode: mode of operations (0, 1 or 2)
@return encrypted data prepended with the initialization vector
"""
if mode == AESModeOfOperation.ModeOfOperation["CBC"]:
data = append_PKCS7_padding(data)
keysize = len(key)
assert keysize in AES.KeySize.values(), 'invalid key size: {}'.format(keysize)
# Create a new iv using random data.
iv = os.urandom(16)
moo = AESModeOfOperation()
(mode, length, ciph) = moo.encrypt(data, mode, key, keysize, iv)
# With padding, the original length does not need to be known.
# It's a bad idea to store the original message length prepend the iv.
return iv + bytes(ciph)
def decryptData(key, data, mode=AESModeOfOperation.ModeOfOperation["CBC"]):
""" Module function to decrypt the given data with the given key.
@param key: key to be used for decryption
@param data: data to be decrypted with initialization vector prepended
@param mode: mode of operations (0, 1 or 2)
@return decrypted data
"""
keysize = len(key)
assert keysize in AES.KeySize.values(), 'invalid key size: {}'.format(keysize)
# iv is first 16 bytes.
iv = data[:16]
data = data[16:]
moo = AESModeOfOperation()
decr = moo.decrypt(data, None, mode, key, keysize, iv)
if mode == AESModeOfOperation.ModeOfOperation["CBC"]:
decr = strip_PKCS7_padding(decr)
return decr
class Test(object):
def generateRandomKey(self, keysize):
""" Generates a key from random data of length `keysize`.
The returned key is a string of bytes.
"""
if keysize not in (16, 24, 32):
raise ValueError('Invalid keysize, %s. Should be one of (16, 24, 32).' % keysize)
return os.urandom(keysize)
def testString(self, cleartext, keysize = 16, modeName = "CBC"):
""" Test with random key, choice of mode. """
print('Random key test with Mode:', modeName)
print('ClearText:', cleartext)
key = self.generateRandomKey(keysize)
print('Key:', bytes([x for x in key]))
mode = AESModeOfOperation.ModeOfOperation[modeName]
cipher = encryptData(key, cleartext, mode)
print('Cipher:', bytes([x for x in cipher]))
decr = decryptData(key, cipher, mode)
print('Decrypted:', bytes(decr))
if __name__ == "__main__":
moo = AESModeOfOperation()
cleartext = "This is a test with several blocks ! Some utf-8 characters åäö and test continues"
print('ClearText: %s\n' % cleartext)
cleartext = bytes(cleartext, 'utf-8')
cipherkey = [143, 194, 34, 208, 145, 203, 230, 143, 177, 246, 97, 206, 145, 92, 255, 84]
iv = [103, 35, 148, 239, 76, 213, 47, 118, 255, 222, 123, 176, 106, 134, 98, 92]
mode, orig_len, ciph = moo.encrypt(cleartext, moo.ModeOfOperation["CBC"],
cipherkey, moo.aes.KeySize["SIZE_128"], iv)
print('Encrypt result: mode = %s, length = %s (%s), encrypted = %s\n' % (mode, orig_len, len(cleartext), bytes(ciph)))
decr = moo.decrypt(ciph, orig_len, mode, cipherkey, moo.aes.KeySize["SIZE_128"], iv)
print('Decrypt result: %s\n' % bytes(decr))
Test().testString(cleartext, 16, "CBC")
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