kopia lustrzana https://github.com/markqvist/reticulum
327 wiersze
12 KiB
Python
327 wiersze
12 KiB
Python
# 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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## 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,
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0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88, 0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB,
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0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C, 0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79,
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0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9, 0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08,
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0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6, 0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A,
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0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E, 0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E,
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0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94, 0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF,
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0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, 0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16,
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)
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inv_s_box = (
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0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, 0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB,
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0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, 0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB,
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0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D, 0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E,
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0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, 0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25,
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0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92,
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0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA, 0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84,
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0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, 0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06,
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0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, 0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B,
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0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA, 0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73,
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0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, 0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E,
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0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, 0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B,
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0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20, 0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4,
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0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, 0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F,
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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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)
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## AES AddRoundKey
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# Round constants https://en.wikipedia.org/wiki/AES_key_schedule#Round_constants
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r_con = (
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0x00, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40,
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0x80, 0x1B, 0x36, 0x6C, 0xD8, 0xAB, 0x4D, 0x9A,
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0x2F, 0x5E, 0xBC, 0x63, 0xC6, 0x97, 0x35, 0x6A,
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0xD4, 0xB3, 0x7D, 0xFA, 0xEF, 0xC5, 0x91, 0x39,
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)
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def add_round_key(s, k):
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for i in range(4):
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for j in range(4):
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s[i][j] ^= k[i][j]
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## AES SubBytes
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def sub_bytes(s):
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for i in range(4):
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for j in range(4):
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s[i][j] = s_box[s[i][j]]
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def inv_sub_bytes(s):
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for i in range(4):
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for j in range(4):
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s[i][j] = inv_s_box[s[i][j]]
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## AES ShiftRows
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def shift_rows(s):
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s[0][1], s[1][1], s[2][1], s[3][1] = s[1][1], s[2][1], s[3][1], s[0][1]
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s[0][2], s[1][2], s[2][2], s[3][2] = s[2][2], s[3][2], s[0][2], s[1][2]
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s[0][3], s[1][3], s[2][3], s[3][3] = s[3][3], s[0][3], s[1][3], s[2][3]
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def inv_shift_rows(s):
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s[0][1], s[1][1], s[2][1], s[3][1] = s[3][1], s[0][1], s[1][1], s[2][1]
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s[0][2], s[1][2], s[2][2], s[3][2] = s[2][2], s[3][2], s[0][2], s[1][2]
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s[0][3], s[1][3], s[2][3], s[3][3] = s[1][3], s[2][3], s[3][3], s[0][3]
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## AES MixColumns
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# learned from http://cs.ucsb.edu/~koc/cs178/projects/JT/aes.c
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xtime = lambda a: (((a << 1) ^ 0x1B) & 0xFF) if (a & 0x80) else (a << 1)
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def mix_single_column(a):
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# see Sec 4.1.2 in The Design of Rijndael
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t = a[0] ^ a[1] ^ a[2] ^ a[3]
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u = a[0]
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a[0] ^= t ^ xtime(a[0] ^ a[1])
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a[1] ^= t ^ xtime(a[1] ^ a[2])
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a[2] ^= t ^ xtime(a[2] ^ a[3])
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a[3] ^= t ^ xtime(a[3] ^ u)
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def mix_columns(s):
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for i in range(4):
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mix_single_column(s[i])
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def inv_mix_columns(s):
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# see Sec 4.1.3 in The Design of Rijndael
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for i in range(4):
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u = xtime(xtime(s[i][0] ^ s[i][2]))
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v = xtime(xtime(s[i][1] ^ s[i][3]))
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s[i][0] ^= u
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s[i][1] ^= v
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s[i][2] ^= u
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s[i][3] ^= v
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mix_columns(s)
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## AES Bytes
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def bytes2matrix(text):
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""" Converts a 16-byte array into a 4x4 matrix. """
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return [list(text[i:i+4]) for i in range(0, len(text), 4)]
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def matrix2bytes(matrix):
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""" Converts a 4x4 matrix into a 16-byte array. """
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return bytes(sum(matrix, []))
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def xor_bytes(a, b):
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""" Returns a new byte array with the elements xor'ed. """
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return bytes(i^j for i, j in zip(a, b))
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def split_blocks(message, block_size=16, require_padding=True):
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assert len(message) % block_size == 0 or not require_padding
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return [message[i:i+16] for i in range(0, len(message), block_size)]
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class AES128:
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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) == AES128.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) == AES128.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) == AES128.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) == AES128.block_size
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assert len(plaintext) % AES128.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) == AES128.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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