Added internal python-only AES-128-CBC implementation

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 .aes import AES
-    from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
     
 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 = AES(key)
-            cipher = Cipher(algorithms.AES(key), modes.CBC(iv))
+            return cipher.encrypt(plaintext, iv)
-            encryptor = cipher.encryptor()
-            ciphertext = encryptor.update(plaintext) + encryptor.finalize()
-            return ciphertext
 
         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 = AES(key)
-            cipher = Cipher(algorithms.AES(key), modes.CBC(iv))
+            return cipher.decrypt(ciphertext, iv)
-            decryptor = cipher.decryptor()
-            plaintext = decryptor.update(ciphertext) + decryptor.finalize()
-            return plaintext
 
         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
-

RNS/Cryptography/aes/__init__.py

@@ -0,0 +1 @@
+from .aes import AES

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()    

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)]