From 68cd79768ba95bb1348cbd113121abc4df11d3fd Mon Sep 17 00:00:00 2001 From: Mark Qvist Date: Thu, 9 Jun 2022 21:13:24 +0200 Subject: [PATCH] Added internal python-only AES-128-CBC implementation --- RNS/Cryptography/AES.py | 18 +- RNS/Cryptography/aes/__init__.py | 1 + RNS/Cryptography/aes/aes.py | 271 +++++++++++++++++++++++++++++++ RNS/Cryptography/aes/utils.py | 159 ++++++++++++++++++ 4 files changed, 436 insertions(+), 13 deletions(-) create mode 100644 RNS/Cryptography/aes/__init__.py create mode 100644 RNS/Cryptography/aes/aes.py create mode 100644 RNS/Cryptography/aes/utils.py diff --git a/RNS/Cryptography/AES.py b/RNS/Cryptography/AES.py index f4ee30d..931fd7c 100644 --- a/RNS/Cryptography/AES.py +++ b/RNS/Cryptography/AES.py @@ -23,8 +23,7 @@ import RNS.Cryptography.Provider as cp if cp.PROVIDER == cp.PROVIDER_INTERNAL: - # TODO: Use internal AES - from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes + from .aes import AES elif cp.PROVIDER == cp.PROVIDER_PYCA: from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes @@ -35,11 +34,8 @@ class AES_128_CBC: @staticmethod def encrypt(plaintext, key, iv): if cp.PROVIDER == cp.PROVIDER_INTERNAL: - # TODO: Use internal AES - cipher = Cipher(algorithms.AES(key), modes.CBC(iv)) - encryptor = cipher.encryptor() - ciphertext = encryptor.update(plaintext) + encryptor.finalize() - return ciphertext + cipher = AES(key) + return cipher.encrypt(plaintext, iv) elif cp.PROVIDER == cp.PROVIDER_PYCA: cipher = Cipher(algorithms.AES(key), modes.CBC(iv)) @@ -50,15 +46,11 @@ class AES_128_CBC: @staticmethod def decrypt(ciphertext, key, iv): if cp.PROVIDER == cp.PROVIDER_INTERNAL: - # TODO: Use internal AES - cipher = Cipher(algorithms.AES(key), modes.CBC(iv)) - decryptor = cipher.decryptor() - plaintext = decryptor.update(ciphertext) + decryptor.finalize() - return plaintext + cipher = AES(key) + return cipher.decrypt(ciphertext, iv) elif cp.PROVIDER == cp.PROVIDER_PYCA: cipher = Cipher(algorithms.AES(key), modes.CBC(iv)) decryptor = cipher.decryptor() plaintext = decryptor.update(ciphertext) + decryptor.finalize() return plaintext - diff --git a/RNS/Cryptography/aes/__init__.py b/RNS/Cryptography/aes/__init__.py new file mode 100644 index 0000000..60e1669 --- /dev/null +++ b/RNS/Cryptography/aes/__init__.py @@ -0,0 +1 @@ +from .aes import AES \ No newline at end of file diff --git a/RNS/Cryptography/aes/aes.py b/RNS/Cryptography/aes/aes.py new file mode 100644 index 0000000..eabb20b --- /dev/null +++ b/RNS/Cryptography/aes/aes.py @@ -0,0 +1,271 @@ +# MIT License + +# Copyright (c) 2021 Or Gur Arie + +# Permission is hereby granted, free of charge, to any person obtaining a copy +# of this software and associated documentation files (the "Software"), to deal +# in the Software without restriction, including without limitation the rights +# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +# copies of the Software, and to permit persons to whom the Software is +# furnished to do so, subject to the following conditions: + +# The above copyright notice and this permission notice shall be included in all +# copies or substantial portions of the Software. + +# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +# SOFTWARE. + +from .utils import * + + +class AES: + # AES-128 block size + block_size = 16 + # AES-128 encrypts messages with 10 rounds + _rounds = 10 + + + # initiate the AES objecy + def __init__(self, key): + """ + Initializes the object with a given key. + """ + # make sure key length is right + assert len(key) == AES.block_size + + # ExpandKey + self._round_keys = self._expand_key(key) + + + # will perform the AES ExpandKey phase + def _expand_key(self, master_key): + """ + Expands and returns a list of key matrices for the given master_key. + """ + + # Initialize round keys with raw key material. + key_columns = bytes2matrix(master_key) + iteration_size = len(master_key) // 4 + + # Each iteration has exactly as many columns as the key material. + i = 1 + while len(key_columns) < (self._rounds + 1) * 4: + # Copy previous word. + word = list(key_columns[-1]) + + # Perform schedule_core once every "row". + if len(key_columns) % iteration_size == 0: + # Circular shift. + word.append(word.pop(0)) + # Map to S-BOX. + word = [s_box[b] for b in word] + # XOR with first byte of R-CON, since the others bytes of R-CON are 0. + word[0] ^= r_con[i] + i += 1 + elif len(master_key) == 32 and len(key_columns) % iteration_size == 4: + # Run word through S-box in the fourth iteration when using a + # 256-bit key. + word = [s_box[b] for b in word] + + # XOR with equivalent word from previous iteration. + word = bytes(i^j for i, j in zip(word, key_columns[-iteration_size])) + key_columns.append(word) + + # Group key words in 4x4 byte matrices. + return [key_columns[4*i : 4*(i+1)] for i in range(len(key_columns) // 4)] + + + # encrypt a single block of data with AES + def _encrypt_block(self, plaintext): + """ + Encrypts a single block of 16 byte long plaintext. + """ + # length of a single block + assert len(plaintext) == AES.block_size + + # perform on a matrix + state = bytes2matrix(plaintext) + + # AddRoundKey + add_round_key(state, self._round_keys[0]) + + # 9 main rounds + for i in range(1, self._rounds): + # SubBytes + sub_bytes(state) + # ShiftRows + shift_rows(state) + # MixCols + mix_columns(state) + # AddRoundKey + add_round_key(state, self._round_keys[i]) + + # last round, w/t AddRoundKey step + sub_bytes(state) + shift_rows(state) + add_round_key(state, self._round_keys[-1]) + + # return the encrypted matrix as bytes + return matrix2bytes(state) + + + # decrypt a single block of data with AES + def _decrypt_block(self, ciphertext): + """ + Decrypts a single block of 16 byte long ciphertext. + """ + # length of a single block + assert len(ciphertext) == AES.block_size + + # perform on a matrix + state = bytes2matrix(ciphertext) + + # in reverse order, last round is first + add_round_key(state, self._round_keys[-1]) + inv_shift_rows(state) + inv_sub_bytes(state) + + for i in range(self._rounds - 1, 0, -1): + # nain rounds + add_round_key(state, self._round_keys[i]) + inv_mix_columns(state) + inv_shift_rows(state) + inv_sub_bytes(state) + + # initial AddRoundKey phase + add_round_key(state, self._round_keys[0]) + + # return bytes + return matrix2bytes(state) + + + # will encrypt the entire data + def encrypt(self, plaintext, iv): + """ + Encrypts `plaintext` using CBC mode and PKCS#7 padding, with the given + initialization vector (iv). + """ + # iv length must be same as block size + assert len(iv) == AES.block_size + + assert len(plaintext) % AES.block_size == 0 + + ciphertext_blocks = [] + + previous = iv + for plaintext_block in split_blocks(plaintext): + # in CBC mode every block is XOR'd with the previous block + xorred = xor_bytes(plaintext_block, previous) + + # encrypt current block + block = self._encrypt_block(xorred) + previous = block + + # append to ciphertext + ciphertext_blocks.append(block) + + # return as bytes + return b''.join(ciphertext_blocks) + + + # will decrypt the entire data + def decrypt(self, ciphertext, iv): + """ + Decrypts `ciphertext` using CBC mode and PKCS#7 padding, with the given + initialization vector (iv). + """ + # iv length must be same as block size + assert len(iv) == AES.block_size + + plaintext_blocks = [] + + previous = iv + for ciphertext_block in split_blocks(ciphertext): + # in CBC mode every block is XOR'd with the previous block + xorred = xor_bytes(previous, self._decrypt_block(ciphertext_block)) + + # append plaintext + plaintext_blocks.append(xorred) + previous = ciphertext_block + + return b''.join(plaintext_blocks) + + +def test(): + # modules and classes requiered for test only + import os + class bcolors: + OK = '\033[92m' #GREEN + WARNING = '\033[93m' #YELLOW + FAIL = '\033[91m' #RED + RESET = '\033[0m' #RESET COLOR + + # will test AES class by performing an encryption / decryption + print("AES Tests") + print("=========") + + # generate a secret key and print details + key = os.urandom(AES.block_size) + _aes = AES(key) + print(f"Algorithm: AES-CBC-{AES.block_size*8}") + print(f"Secret Key: {key.hex()}") + print() + + # test single block encryption / decryption + iv = os.urandom(AES.block_size) + + single_block_text = b"SingleBlock Text" + print("Single Block Tests") + print("------------------") + print(f"iv: {iv.hex()}") + + print(f"plain text: '{single_block_text.decode()}'") + ciphertext_block = _aes._encrypt_block(single_block_text) + plaintext_block = _aes._decrypt_block(ciphertext_block) + print(f"Ciphertext Hex: {ciphertext_block.hex()}") + print(f"Plaintext: {plaintext_block.decode()}") + assert plaintext_block == single_block_text + print(bcolors.OK + "Single Block Test Passed Successfully" + bcolors.RESET) + print() + + # test a less than a block length phrase + iv = os.urandom(AES.block_size) + + short_text = b"Just Text" + print("Short Text Tests") + print("----------------") + print(f"iv: {iv.hex()}") + print(f"plain text: '{short_text.decode()}'") + ciphertext_short = _aes.encrypt(short_text, iv) + plaintext_short = _aes.decrypt(ciphertext_short, iv) + print(f"Ciphertext Hex: {ciphertext_short.hex()}") + print(f"Plaintext: {plaintext_short.decode()}") + assert short_text == plaintext_short + print(bcolors.OK + "Short Text Test Passed Successfully" + bcolors.RESET) + print() + + # test an arbitrary length phrase + iv = os.urandom(AES.block_size) + + text = b"This Text is longer than one block" + print("Arbitrary Length Tests") + print("----------------------") + print(f"iv: {iv.hex()}") + print(f"plain text: '{text.decode()}'") + ciphertext = _aes.encrypt(text, iv) + plaintext = _aes.decrypt(ciphertext, iv) + print(f"Ciphertext Hex: {ciphertext.hex()}") + print(f"Plaintext: {plaintext.decode()}") + assert text == plaintext + print(bcolors.OK + "Arbitrary Length Text Test Passed Successfully" + bcolors.RESET) + print() + + +if __name__ == "__main__": + # test AES class + test() diff --git a/RNS/Cryptography/aes/utils.py b/RNS/Cryptography/aes/utils.py new file mode 100644 index 0000000..bc0d2dd --- /dev/null +++ b/RNS/Cryptography/aes/utils.py @@ -0,0 +1,159 @@ +# MIT License + +# Copyright (c) 2021 Or Gur Arie + +# Permission is hereby granted, free of charge, to any person obtaining a copy +# of this software and associated documentation files (the "Software"), to deal +# in the Software without restriction, including without limitation the rights +# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +# copies of the Software, and to permit persons to whom the Software is +# furnished to do so, subject to the following conditions: + +# The above copyright notice and this permission notice shall be included in all +# copies or substantial portions of the Software. + +# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +# SOFTWARE. + +''' +Utils class for AES encryption / decryption +''' + +## AES lookup tables +# resource: https://en.wikipedia.org/wiki/Rijndael_S-box +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, +) + +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)] \ No newline at end of file