Added internal python-only AES-128-CBC implementation
This commit is contained in:
Mark Qvist
parent
701c624d0a
commit
68cd79768b
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@ -23,8 +23,7 @@
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import RNS.Cryptography.Provider as cp
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import RNS.Cryptography.Provider as cp
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if cp.PROVIDER == cp.PROVIDER_INTERNAL:
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if cp.PROVIDER == cp.PROVIDER_INTERNAL:
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# TODO: Use internal AES
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from .aes import AES
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from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
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elif cp.PROVIDER == cp.PROVIDER_PYCA:
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elif cp.PROVIDER == cp.PROVIDER_PYCA:
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from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
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from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
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@ -35,11 +34,8 @@ class AES_128_CBC:
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@staticmethod
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@staticmethod
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def encrypt(plaintext, key, iv):
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def encrypt(plaintext, key, iv):
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if cp.PROVIDER == cp.PROVIDER_INTERNAL:
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if cp.PROVIDER == cp.PROVIDER_INTERNAL:
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# TODO: Use internal AES
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cipher = AES(key)
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cipher = Cipher(algorithms.AES(key), modes.CBC(iv))
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return cipher.encrypt(plaintext, iv)
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encryptor = cipher.encryptor()
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ciphertext = encryptor.update(plaintext) + encryptor.finalize()
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return ciphertext
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elif cp.PROVIDER == cp.PROVIDER_PYCA:
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elif cp.PROVIDER == cp.PROVIDER_PYCA:
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cipher = Cipher(algorithms.AES(key), modes.CBC(iv))
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cipher = Cipher(algorithms.AES(key), modes.CBC(iv))
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@ -50,15 +46,11 @@ class AES_128_CBC:
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@staticmethod
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@staticmethod
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def decrypt(ciphertext, key, iv):
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def decrypt(ciphertext, key, iv):
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if cp.PROVIDER == cp.PROVIDER_INTERNAL:
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if cp.PROVIDER == cp.PROVIDER_INTERNAL:
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# TODO: Use internal AES
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cipher = AES(key)
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cipher = Cipher(algorithms.AES(key), modes.CBC(iv))
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return cipher.decrypt(ciphertext, iv)
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decryptor = cipher.decryptor()
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plaintext = decryptor.update(ciphertext) + decryptor.finalize()
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return plaintext
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elif cp.PROVIDER == cp.PROVIDER_PYCA:
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elif cp.PROVIDER == cp.PROVIDER_PYCA:
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cipher = Cipher(algorithms.AES(key), modes.CBC(iv))
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cipher = Cipher(algorithms.AES(key), modes.CBC(iv))
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decryptor = cipher.decryptor()
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decryptor = cipher.decryptor()
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plaintext = decryptor.update(ciphertext) + decryptor.finalize()
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plaintext = decryptor.update(ciphertext) + decryptor.finalize()
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return plaintext
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return plaintext
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@ -0,0 +1 @@
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from .aes import AES
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@ -0,0 +1,271 @@
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# MIT License
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# Copyright (c) 2021 Or Gur Arie
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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# The above copyright notice and this permission notice shall be included in all
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# copies or substantial portions of the Software.
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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from .utils import *
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class AES:
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# AES-128 block size
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block_size = 16
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# AES-128 encrypts messages with 10 rounds
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_rounds = 10
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# initiate the AES objecy
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def __init__(self, key):
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"""
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Initializes the object with a given key.
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"""
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# make sure key length is right
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assert len(key) == AES.block_size
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# ExpandKey
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self._round_keys = self._expand_key(key)
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# will perform the AES ExpandKey phase
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def _expand_key(self, master_key):
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"""
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Expands and returns a list of key matrices for the given master_key.
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"""
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# Initialize round keys with raw key material.
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key_columns = bytes2matrix(master_key)
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iteration_size = len(master_key) // 4
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# Each iteration has exactly as many columns as the key material.
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i = 1
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while len(key_columns) < (self._rounds + 1) * 4:
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# Copy previous word.
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word = list(key_columns[-1])
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# Perform schedule_core once every "row".
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if len(key_columns) % iteration_size == 0:
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# Circular shift.
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word.append(word.pop(0))
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# Map to S-BOX.
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word = [s_box[b] for b in word]
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# XOR with first byte of R-CON, since the others bytes of R-CON are 0.
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word[0] ^= r_con[i]
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i += 1
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elif len(master_key) == 32 and len(key_columns) % iteration_size == 4:
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# Run word through S-box in the fourth iteration when using a
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# 256-bit key.
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word = [s_box[b] for b in word]
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# XOR with equivalent word from previous iteration.
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word = bytes(i^j for i, j in zip(word, key_columns[-iteration_size]))
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key_columns.append(word)
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# Group key words in 4x4 byte matrices.
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return [key_columns[4*i : 4*(i+1)] for i in range(len(key_columns) // 4)]
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# encrypt a single block of data with AES
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def _encrypt_block(self, plaintext):
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"""
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Encrypts a single block of 16 byte long plaintext.
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"""
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# length of a single block
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assert len(plaintext) == AES.block_size
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# perform on a matrix
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state = bytes2matrix(plaintext)
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# AddRoundKey
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add_round_key(state, self._round_keys[0])
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# 9 main rounds
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for i in range(1, self._rounds):
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# SubBytes
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sub_bytes(state)
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# ShiftRows
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shift_rows(state)
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# MixCols
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mix_columns(state)
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# AddRoundKey
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add_round_key(state, self._round_keys[i])
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# last round, w/t AddRoundKey step
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sub_bytes(state)
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shift_rows(state)
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add_round_key(state, self._round_keys[-1])
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# return the encrypted matrix as bytes
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return matrix2bytes(state)
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# decrypt a single block of data with AES
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def _decrypt_block(self, ciphertext):
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"""
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Decrypts a single block of 16 byte long ciphertext.
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"""
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# length of a single block
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assert len(ciphertext) == AES.block_size
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# perform on a matrix
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state = bytes2matrix(ciphertext)
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# in reverse order, last round is first
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add_round_key(state, self._round_keys[-1])
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inv_shift_rows(state)
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inv_sub_bytes(state)
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for i in range(self._rounds - 1, 0, -1):
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# nain rounds
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add_round_key(state, self._round_keys[i])
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inv_mix_columns(state)
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inv_shift_rows(state)
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inv_sub_bytes(state)
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# initial AddRoundKey phase
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add_round_key(state, self._round_keys[0])
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# return bytes
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return matrix2bytes(state)
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# will encrypt the entire data
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def encrypt(self, plaintext, iv):
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"""
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Encrypts `plaintext` using CBC mode and PKCS#7 padding, with the given
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initialization vector (iv).
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"""
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# iv length must be same as block size
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assert len(iv) == AES.block_size
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assert len(plaintext) % AES.block_size == 0
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ciphertext_blocks = []
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previous = iv
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for plaintext_block in split_blocks(plaintext):
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# in CBC mode every block is XOR'd with the previous block
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xorred = xor_bytes(plaintext_block, previous)
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# encrypt current block
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block = self._encrypt_block(xorred)
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previous = block
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# append to ciphertext
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ciphertext_blocks.append(block)
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# return as bytes
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return b''.join(ciphertext_blocks)
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# will decrypt the entire data
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def decrypt(self, ciphertext, iv):
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"""
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Decrypts `ciphertext` using CBC mode and PKCS#7 padding, with the given
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initialization vector (iv).
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"""
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# iv length must be same as block size
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assert len(iv) == AES.block_size
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plaintext_blocks = []
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previous = iv
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for ciphertext_block in split_blocks(ciphertext):
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# in CBC mode every block is XOR'd with the previous block
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xorred = xor_bytes(previous, self._decrypt_block(ciphertext_block))
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# append plaintext
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plaintext_blocks.append(xorred)
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previous = ciphertext_block
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return b''.join(plaintext_blocks)
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def test():
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# modules and classes requiered for test only
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import os
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class bcolors:
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OK = '\033[92m' #GREEN
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WARNING = '\033[93m' #YELLOW
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FAIL = '\033[91m' #RED
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RESET = '\033[0m' #RESET COLOR
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# will test AES class by performing an encryption / decryption
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print("AES Tests")
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print("=========")
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# generate a secret key and print details
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key = os.urandom(AES.block_size)
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_aes = AES(key)
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print(f"Algorithm: AES-CBC-{AES.block_size*8}")
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print(f"Secret Key: {key.hex()}")
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print()
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# test single block encryption / decryption
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iv = os.urandom(AES.block_size)
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single_block_text = b"SingleBlock Text"
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print("Single Block Tests")
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print("------------------")
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print(f"iv: {iv.hex()}")
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print(f"plain text: '{single_block_text.decode()}'")
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ciphertext_block = _aes._encrypt_block(single_block_text)
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plaintext_block = _aes._decrypt_block(ciphertext_block)
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print(f"Ciphertext Hex: {ciphertext_block.hex()}")
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print(f"Plaintext: {plaintext_block.decode()}")
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assert plaintext_block == single_block_text
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print(bcolors.OK + "Single Block Test Passed Successfully" + bcolors.RESET)
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print()
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# test a less than a block length phrase
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iv = os.urandom(AES.block_size)
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short_text = b"Just Text"
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print("Short Text Tests")
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print("----------------")
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print(f"iv: {iv.hex()}")
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print(f"plain text: '{short_text.decode()}'")
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ciphertext_short = _aes.encrypt(short_text, iv)
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plaintext_short = _aes.decrypt(ciphertext_short, iv)
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print(f"Ciphertext Hex: {ciphertext_short.hex()}")
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print(f"Plaintext: {plaintext_short.decode()}")
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assert short_text == plaintext_short
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print(bcolors.OK + "Short Text Test Passed Successfully" + bcolors.RESET)
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print()
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# test an arbitrary length phrase
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iv = os.urandom(AES.block_size)
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text = b"This Text is longer than one block"
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print("Arbitrary Length Tests")
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print("----------------------")
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print(f"iv: {iv.hex()}")
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print(f"plain text: '{text.decode()}'")
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ciphertext = _aes.encrypt(text, iv)
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plaintext = _aes.decrypt(ciphertext, iv)
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print(f"Ciphertext Hex: {ciphertext.hex()}")
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print(f"Plaintext: {plaintext.decode()}")
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assert text == plaintext
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print(bcolors.OK + "Arbitrary Length Text Test Passed Successfully" + bcolors.RESET)
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print()
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if __name__ == "__main__":
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# test AES class
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test()
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@ -0,0 +1,159 @@
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# MIT License
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# Copyright (c) 2021 Or Gur Arie
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
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# copies of the Software, and to permit persons to whom the Software is
|
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|
# furnished to do so, subject to the following conditions:
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# The above copyright notice and this permission notice shall be included in all
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# copies or substantial portions of the Software.
|
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|
|
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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'''
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Utils class for AES encryption / decryption
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'''
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## AES lookup tables
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# resource: https://en.wikipedia.org/wiki/Rijndael_S-box
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s_box = (
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0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, 0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76,
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0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, 0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0,
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0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC, 0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15,
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0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A, 0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75,
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0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0, 0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84,
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0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B, 0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF,
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0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85, 0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8,
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0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5, 0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2,
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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,
|
||||||
|
)
|
||||||
|
|
||||||
|
inv_s_box = (
|
||||||
|
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,
|
||||||
|
)
|
||||||
|
|
||||||
|
|
||||||
|
## AES AddRoundKey
|
||||||
|
# Round constants https://en.wikipedia.org/wiki/AES_key_schedule#Round_constants
|
||||||
|
r_con = (
|
||||||
|
0x00, 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,
|
||||||
|
)
|
||||||
|
|
||||||
|
def add_round_key(s, k):
|
||||||
|
for i in range(4):
|
||||||
|
for j in range(4):
|
||||||
|
s[i][j] ^= k[i][j]
|
||||||
|
|
||||||
|
|
||||||
|
## AES SubBytes
|
||||||
|
def sub_bytes(s):
|
||||||
|
for i in range(4):
|
||||||
|
for j in range(4):
|
||||||
|
s[i][j] = s_box[s[i][j]]
|
||||||
|
|
||||||
|
|
||||||
|
def inv_sub_bytes(s):
|
||||||
|
for i in range(4):
|
||||||
|
for j in range(4):
|
||||||
|
s[i][j] = inv_s_box[s[i][j]]
|
||||||
|
|
||||||
|
|
||||||
|
## AES ShiftRows
|
||||||
|
def shift_rows(s):
|
||||||
|
s[0][1], s[1][1], s[2][1], s[3][1] = s[1][1], s[2][1], s[3][1], s[0][1]
|
||||||
|
s[0][2], s[1][2], s[2][2], s[3][2] = s[2][2], s[3][2], s[0][2], s[1][2]
|
||||||
|
s[0][3], s[1][3], s[2][3], s[3][3] = s[3][3], s[0][3], s[1][3], s[2][3]
|
||||||
|
|
||||||
|
|
||||||
|
def inv_shift_rows(s):
|
||||||
|
s[0][1], s[1][1], s[2][1], s[3][1] = s[3][1], s[0][1], s[1][1], s[2][1]
|
||||||
|
s[0][2], s[1][2], s[2][2], s[3][2] = s[2][2], s[3][2], s[0][2], s[1][2]
|
||||||
|
s[0][3], s[1][3], s[2][3], s[3][3] = s[1][3], s[2][3], s[3][3], s[0][3]
|
||||||
|
|
||||||
|
|
||||||
|
## AES MixColumns
|
||||||
|
# learned from http://cs.ucsb.edu/~koc/cs178/projects/JT/aes.c
|
||||||
|
xtime = lambda a: (((a << 1) ^ 0x1B) & 0xFF) if (a & 0x80) else (a << 1)
|
||||||
|
|
||||||
|
|
||||||
|
def mix_single_column(a):
|
||||||
|
# see Sec 4.1.2 in The Design of Rijndael
|
||||||
|
t = a[0] ^ a[1] ^ a[2] ^ a[3]
|
||||||
|
u = a[0]
|
||||||
|
a[0] ^= t ^ xtime(a[0] ^ a[1])
|
||||||
|
a[1] ^= t ^ xtime(a[1] ^ a[2])
|
||||||
|
a[2] ^= t ^ xtime(a[2] ^ a[3])
|
||||||
|
a[3] ^= t ^ xtime(a[3] ^ u)
|
||||||
|
|
||||||
|
|
||||||
|
def mix_columns(s):
|
||||||
|
for i in range(4):
|
||||||
|
mix_single_column(s[i])
|
||||||
|
|
||||||
|
|
||||||
|
def inv_mix_columns(s):
|
||||||
|
# see Sec 4.1.3 in The Design of Rijndael
|
||||||
|
for i in range(4):
|
||||||
|
u = xtime(xtime(s[i][0] ^ s[i][2]))
|
||||||
|
v = xtime(xtime(s[i][1] ^ s[i][3]))
|
||||||
|
s[i][0] ^= u
|
||||||
|
s[i][1] ^= v
|
||||||
|
s[i][2] ^= u
|
||||||
|
s[i][3] ^= v
|
||||||
|
|
||||||
|
mix_columns(s)
|
||||||
|
|
||||||
|
|
||||||
|
## AES Bytes
|
||||||
|
def bytes2matrix(text):
|
||||||
|
""" Converts a 16-byte array into a 4x4 matrix. """
|
||||||
|
return [list(text[i:i+4]) for i in range(0, len(text), 4)]
|
||||||
|
|
||||||
|
def matrix2bytes(matrix):
|
||||||
|
""" Converts a 4x4 matrix into a 16-byte array. """
|
||||||
|
return bytes(sum(matrix, []))
|
||||||
|
|
||||||
|
|
||||||
|
def xor_bytes(a, b):
|
||||||
|
""" Returns a new byte array with the elements xor'ed. """
|
||||||
|
return bytes(i^j for i, j in zip(a, b))
|
||||||
|
|
||||||
|
|
||||||
|
def split_blocks(message, block_size=16, require_padding=True):
|
||||||
|
assert len(message) % block_size == 0 or not require_padding
|
||||||
|
return [message[i:i+16] for i in range(0, len(message), block_size)]
|
||||||
Loading…
Reference in New Issue