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@ -7,10 +7,11 @@ from .utils import bytes_to_intlist, intlist_to_bytes |
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BLOCK_SIZE_BYTES = 16 |
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def aes_ctr_decrypt(data, key, counter): |
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""" |
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Decrypt with aes in counter mode |
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@param {int[]} data cipher |
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@param {int[]} key 16/24/32-Byte cipher key |
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@param {instance} counter Instance whose next_value function (@returns {int[]} 16-Byte block) |
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@ -19,23 +20,24 @@ def aes_ctr_decrypt(data, key, counter): |
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""" |
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expanded_key = key_expansion(key) |
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block_count = int(ceil(float(len(data)) / BLOCK_SIZE_BYTES)) |
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decrypted_data=[] |
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decrypted_data = [] |
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for i in range(block_count): |
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counter_block = counter.next_value() |
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block = data[i*BLOCK_SIZE_BYTES : (i+1)*BLOCK_SIZE_BYTES] |
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block = data[i*BLOCK_SIZE_BYTES: (i+1)*BLOCK_SIZE_BYTES] |
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block += [0]*(BLOCK_SIZE_BYTES - len(block)) |
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cipher_counter_block = aes_encrypt(counter_block, expanded_key) |
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decrypted_data += xor(block, cipher_counter_block) |
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decrypted_data = decrypted_data[:len(data)] |
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return decrypted_data |
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def aes_cbc_decrypt(data, key, iv): |
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""" |
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Decrypt with aes in CBC mode |
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@param {int[]} data cipher |
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@param {int[]} key 16/24/32-Byte cipher key |
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@param {int[]} iv 16-Byte IV |
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@ -43,60 +45,62 @@ def aes_cbc_decrypt(data, key, iv): |
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""" |
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expanded_key = key_expansion(key) |
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block_count = int(ceil(float(len(data)) / BLOCK_SIZE_BYTES)) |
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decrypted_data=[] |
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decrypted_data = [] |
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previous_cipher_block = iv |
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for i in range(block_count): |
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block = data[i*BLOCK_SIZE_BYTES : (i+1)*BLOCK_SIZE_BYTES] |
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block = data[i*BLOCK_SIZE_BYTES: (i+1)*BLOCK_SIZE_BYTES] |
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block += [0]*(BLOCK_SIZE_BYTES - len(block)) |
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decrypted_block = aes_decrypt(block, expanded_key) |
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decrypted_data += xor(decrypted_block, previous_cipher_block) |
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previous_cipher_block = block |
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decrypted_data = decrypted_data[:len(data)] |
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return decrypted_data |
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def key_expansion(data): |
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""" |
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Generate key schedule |
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@param {int[]} data 16/24/32-Byte cipher key |
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@returns {int[]} 176/208/240-Byte expanded key |
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@returns {int[]} 176/208/240-Byte expanded key |
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""" |
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data = data[:] # copy |
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data = data[:] # copy |
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rcon_iteration = 1 |
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key_size_bytes = len(data) |
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expanded_key_size_bytes = (key_size_bytes // 4 + 7) * BLOCK_SIZE_BYTES |
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while len(data) < expanded_key_size_bytes: |
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temp = data[-4:] |
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temp = key_schedule_core(temp, rcon_iteration) |
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rcon_iteration += 1 |
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data += xor(temp, data[-key_size_bytes : 4-key_size_bytes]) |
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data += xor(temp, data[-key_size_bytes: 4-key_size_bytes]) |
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for _ in range(3): |
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temp = data[-4:] |
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data += xor(temp, data[-key_size_bytes : 4-key_size_bytes]) |
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data += xor(temp, data[-key_size_bytes: 4-key_size_bytes]) |
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if key_size_bytes == 32: |
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temp = data[-4:] |
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temp = sub_bytes(temp) |
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data += xor(temp, data[-key_size_bytes : 4-key_size_bytes]) |
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data += xor(temp, data[-key_size_bytes: 4-key_size_bytes]) |
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for _ in range(3 if key_size_bytes == 32 else 2 if key_size_bytes == 24 else 0): |
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temp = data[-4:] |
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data += xor(temp, data[-key_size_bytes : 4-key_size_bytes]) |
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data += xor(temp, data[-key_size_bytes: 4-key_size_bytes]) |
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data = data[:expanded_key_size_bytes] |
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return data |
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def aes_encrypt(data, expanded_key): |
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""" |
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Encrypt one block with aes |
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@param {int[]} data 16-Byte state |
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@param {int[]} expanded_key 176/208/240-Byte expanded key |
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@param {int[]} expanded_key 176/208/240-Byte expanded key |
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@returns {int[]} 16-Byte cipher |
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""" |
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rounds = len(expanded_key) // BLOCK_SIZE_BYTES - 1 |
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@ -107,30 +111,32 @@ def aes_encrypt(data, expanded_key): |
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data = shift_rows(data) |
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if i != rounds: |
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data = mix_columns(data) |
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data = xor(data, expanded_key[i*BLOCK_SIZE_BYTES : (i+1)*BLOCK_SIZE_BYTES]) |
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data = xor(data, expanded_key[i*BLOCK_SIZE_BYTES: (i+1)*BLOCK_SIZE_BYTES]) |
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return data |
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def aes_decrypt(data, expanded_key): |
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""" |
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Decrypt one block with aes |
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@param {int[]} data 16-Byte cipher |
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@param {int[]} expanded_key 176/208/240-Byte expanded key |
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@returns {int[]} 16-Byte state |
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""" |
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rounds = len(expanded_key) // BLOCK_SIZE_BYTES - 1 |
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for i in range(rounds, 0, -1): |
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data = xor(data, expanded_key[i*BLOCK_SIZE_BYTES : (i+1)*BLOCK_SIZE_BYTES]) |
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data = xor(data, expanded_key[i*BLOCK_SIZE_BYTES: (i+1)*BLOCK_SIZE_BYTES]) |
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if i != rounds: |
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data = mix_columns_inv(data) |
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data = shift_rows_inv(data) |
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data = sub_bytes_inv(data) |
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data = xor(data, expanded_key[:BLOCK_SIZE_BYTES]) |
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return data |
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def aes_decrypt_text(data, password, key_size_bytes): |
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""" |
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Decrypt text |
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@ -138,33 +144,34 @@ def aes_decrypt_text(data, password, key_size_bytes): |
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- The cipher key is retrieved by encrypting the first 16 Byte of 'password' |
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with the first 'key_size_bytes' Bytes from 'password' (if necessary filled with 0's) |
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- Mode of operation is 'counter' |
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@param {str} data Base64 encoded string |
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@param {str,unicode} password Password (will be encoded with utf-8) |
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@param {int} key_size_bytes Possible values: 16 for 128-Bit, 24 for 192-Bit or 32 for 256-Bit |
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@returns {str} Decrypted data |
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""" |
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NONCE_LENGTH_BYTES = 8 |
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data = bytes_to_intlist(base64.b64decode(data)) |
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password = bytes_to_intlist(password.encode('utf-8')) |
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key = password[:key_size_bytes] + [0]*(key_size_bytes - len(password)) |
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key = aes_encrypt(key[:BLOCK_SIZE_BYTES], key_expansion(key)) * (key_size_bytes // BLOCK_SIZE_BYTES) |
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nonce = data[:NONCE_LENGTH_BYTES] |
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cipher = data[NONCE_LENGTH_BYTES:] |
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class Counter: |
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__value = nonce + [0]*(BLOCK_SIZE_BYTES - NONCE_LENGTH_BYTES) |
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def next_value(self): |
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temp = self.__value |
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self.__value = inc(self.__value) |
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return temp |
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decrypted_data = aes_ctr_decrypt(cipher, key, Counter()) |
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plaintext = intlist_to_bytes(decrypted_data) |
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return plaintext |
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RCON = (0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36) |
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@ -200,14 +207,14 @@ SBOX_INV = (0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x |
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0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef, |
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0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61, |
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0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d) |
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MIX_COLUMN_MATRIX = ((0x2,0x3,0x1,0x1), |
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(0x1,0x2,0x3,0x1), |
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(0x1,0x1,0x2,0x3), |
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(0x3,0x1,0x1,0x2)) |
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MIX_COLUMN_MATRIX_INV = ((0xE,0xB,0xD,0x9), |
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(0x9,0xE,0xB,0xD), |
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(0xD,0x9,0xE,0xB), |
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(0xB,0xD,0x9,0xE)) |
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MIX_COLUMN_MATRIX = ((0x2, 0x3, 0x1, 0x1), |
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(0x1, 0x2, 0x3, 0x1), |
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(0x1, 0x1, 0x2, 0x3), |
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(0x3, 0x1, 0x1, 0x2)) |
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MIX_COLUMN_MATRIX_INV = ((0xE, 0xB, 0xD, 0x9), |
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(0x9, 0xE, 0xB, 0xD), |
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(0xD, 0x9, 0xE, 0xB), |
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(0xB, 0xD, 0x9, 0xE)) |
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RIJNDAEL_EXP_TABLE = (0x01, 0x03, 0x05, 0x0F, 0x11, 0x33, 0x55, 0xFF, 0x1A, 0x2E, 0x72, 0x96, 0xA1, 0xF8, 0x13, 0x35, |
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0x5F, 0xE1, 0x38, 0x48, 0xD8, 0x73, 0x95, 0xA4, 0xF7, 0x02, 0x06, 0x0A, 0x1E, 0x22, 0x66, 0xAA, |
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0xE5, 0x34, 0x5C, 0xE4, 0x37, 0x59, 0xEB, 0x26, 0x6A, 0xBE, 0xD9, 0x70, 0x90, 0xAB, 0xE6, 0x31, |
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@ -241,30 +248,37 @@ RIJNDAEL_LOG_TABLE = (0x00, 0x00, 0x19, 0x01, 0x32, 0x02, 0x1a, 0xc6, 0x4b, 0xc7 |
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0x44, 0x11, 0x92, 0xd9, 0x23, 0x20, 0x2e, 0x89, 0xb4, 0x7c, 0xb8, 0x26, 0x77, 0x99, 0xe3, 0xa5, |
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0x67, 0x4a, 0xed, 0xde, 0xc5, 0x31, 0xfe, 0x18, 0x0d, 0x63, 0x8c, 0x80, 0xc0, 0xf7, 0x70, 0x07) |
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def sub_bytes(data): |
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return [SBOX[x] for x in data] |
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def sub_bytes_inv(data): |
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return [SBOX_INV[x] for x in data] |
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def rotate(data): |
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return data[1:] + [data[0]] |
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def key_schedule_core(data, rcon_iteration): |
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data = rotate(data) |
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data = sub_bytes(data) |
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data[0] = data[0] ^ RCON[rcon_iteration] |
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return data |
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def xor(data1, data2): |
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return [x^y for x, y in zip(data1, data2)] |
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def rijndael_mul(a, b): |
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if(a==0 or b==0): |
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if(a == 0 or b == 0): |
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return 0 |
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return RIJNDAEL_EXP_TABLE[(RIJNDAEL_LOG_TABLE[a] + RIJNDAEL_LOG_TABLE[b]) % 0xFF] |
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def mix_column(data, matrix): |
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data_mixed = [] |
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for row in range(4): |
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@ -275,33 +289,38 @@ def mix_column(data, matrix): |
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data_mixed.append(mixed) |
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return data_mixed |
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def mix_columns(data, matrix=MIX_COLUMN_MATRIX): |
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data_mixed = [] |
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for i in range(4): |
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column = data[i*4 : (i+1)*4] |
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column = data[i*4: (i+1)*4] |
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data_mixed += mix_column(column, matrix) |
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return data_mixed |
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def mix_columns_inv(data): |
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return mix_columns(data, MIX_COLUMN_MATRIX_INV) |
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def shift_rows(data): |
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data_shifted = [] |
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for column in range(4): |
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for row in range(4): |
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data_shifted.append( data[((column + row) & 0b11) * 4 + row] ) |
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data_shifted.append(data[((column + row) & 0b11) * 4 + row]) |
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return data_shifted |
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def shift_rows_inv(data): |
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data_shifted = [] |
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for column in range(4): |
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for row in range(4): |
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data_shifted.append( data[((column - row) & 0b11) * 4 + row] ) |
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data_shifted.append(data[((column - row) & 0b11) * 4 + row]) |
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return data_shifted |
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def inc(data): |
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data = data[:] # copy |
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for i in range(len(data)-1,-1,-1): |
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data = data[:] # copy |
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for i in range(len(data)-1, -1, -1): |
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if data[i] == 255: |
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data[i] = 0 |
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else: |
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Jouke Waleson
8 years ago