#!/usr/bin/env python3 from os import urandom from utils import listener FLAG = b'crypto{????????????????????????????}' class AES: sbox = ( 0x2a, 0x00, 0x7e, 0x54, 0x82, 0xa8, 0xd6, 0xfc, 0x61, 0x4b, 0x35, 0x1f, 0xc9, 0xe3, 0x9d, 0xb7, 0xbc, 0x96, 0xe8, 0xc2, 0x14, 0x3e, 0x40, 0x6a, 0xf7, 0xdd, 0xa3, 0x89, 0x5f, 0x75, 0x0b, 0x21, 0x1d, 0x37, 0x49, 0x63, 0xb5, 0x9f, 0xe1, 0xcb, 0x56, 0x7c, 0x02, 0x28, 0xfe, 0xd4, 0xaa, 0x80, 0x8b, 0xa1, 0xdf, 0xf5, 0x23, 0x09, 0x77, 0x5d, 0xc0, 0xea, 0x94, 0xbe, 0x68, 0x42, 0x3c, 0x16, 0x44, 0x6e, 0x10, 0x3a, 0xec, 0xc6, 0xb8, 0x92, 0x0f, 0x25, 0x5b, 0x71, 0xa7, 0x8d, 0xf3, 0xd9, 0xd2, 0xf8, 0x86, 0xac, 0x7a, 0x50, 0x2e, 0x04, 0x99, 0xb3, 0xcd, 0xe7, 0x31, 0x1b, 0x65, 0x4f, 0x73, 0x59, 0x27, 0x0d, 0xdb, 0xf1, 0x8f, 0xa5, 0x38, 0x12, 0x6c, 0x46, 0x90, 0xba, 0xc4, 0xee, 0xe5, 0xcf, 0xb1, 0x9b, 0x4d, 0x67, 0x19, 0x33, 0xae, 0x84, 0xfa, 0xd0, 0x06, 0x2c, 0x52, 0x78, 0xf6, 0xdc, 0xa2, 0x88, 0x5e, 0x74, 0x0a, 0x20, 0xbd, 0x97, 0xe9, 0xc3, 0x15, 0x3f, 0x41, 0x6b, 0x60, 0x4a, 0x34, 0x1e, 0xc8, 0xe2, 0x9c, 0xb6, 0x2b, 0x01, 0x7f, 0x55, 0x83, 0xa9, 0xd7, 0xfd, 0xc1, 0xeb, 0x95, 0xbf, 0x69, 0x43, 0x3d, 0x17, 0x8a, 0xa0, 0xde, 0xf4, 0x22, 0x08, 0x76, 0x5c, 0x57, 0x7d, 0x03, 0x29, 0xff, 0xd5, 0xab, 0x81, 0x1c, 0x36, 0x48, 0x62, 0xb4, 0x9e, 0xe0, 0xca, 0x98, 0xb2, 0xcc, 0xe6, 0x30, 0x1a, 0x64, 0x4e, 0xd3, 0xf9, 0x87, 0xad, 0x7b, 0x51, 0x2f, 0x05, 0x0e, 0x24, 0x5a, 0x70, 0xa6, 0x8c, 0xf2, 0xd8, 0x45, 0x6f, 0x11, 0x3b, 0xed, 0xc7, 0xb9, 0x93, 0xaf, 0x85, 0xfb, 0xd1, 0x07, 0x2d, 0x53, 0x79, 0xe4, 0xce, 0xb0, 0x9a, 0x4c, 0x66, 0x18, 0x32, 0x39, 0x13, 0x6d, 0x47, 0x91, 0xbb, 0xc5, 0xef, 0x72, 0x58, 0x26, 0x0c, 0xda, 0xf0, 0x8e, 0xa4 ) rcon = (0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36) gmul2 = ( 0x00, 0x02, 0x04, 0x06, 0x08, 0x0a, 0x0c, 0x0e, 0x10, 0x12, 0x14, 0x16, 0x18, 0x1a, 0x1c, 0x1e, 0x20, 0x22, 0x24, 0x26, 0x28, 0x2a, 0x2c, 0x2e, 0x30, 0x32, 0x34, 0x36, 0x38, 0x3a, 0x3c, 0x3e, 0x40, 0x42, 0x44, 0x46, 0x48, 0x4a, 0x4c, 0x4e, 0x50, 0x52, 0x54, 0x56, 0x58, 0x5a, 0x5c, 0x5e, 0x60, 0x62, 0x64, 0x66, 0x68, 0x6a, 0x6c, 0x6e, 0x70, 0x72, 0x74, 0x76, 0x78, 0x7a, 0x7c, 0x7e, 0x80, 0x82, 0x84, 0x86, 0x88, 0x8a, 0x8c, 0x8e, 0x90, 0x92, 0x94, 0x96, 0x98, 0x9a, 0x9c, 0x9e, 0xa0, 0xa2, 0xa4, 0xa6, 0xa8, 0xaa, 0xac, 0xae, 0xb0, 0xb2, 0xb4, 0xb6, 0xb8, 0xba, 0xbc, 0xbe, 0xc0, 0xc2, 0xc4, 0xc6, 0xc8, 0xca, 0xcc, 0xce, 0xd0, 0xd2, 0xd4, 0xd6, 0xd8, 0xda, 0xdc, 0xde, 0xe0, 0xe2, 0xe4, 0xe6, 0xe8, 0xea, 0xec, 0xee, 0xf0, 0xf2, 0xf4, 0xf6, 0xf8, 0xfa, 0xfc, 0xfe, 0x1b, 0x19, 0x1f, 0x1d, 0x13, 0x11, 0x17, 0x15, 0x0b, 0x09, 0x0f, 0x0d, 0x03, 0x01, 0x07, 0x05, 0x3b, 0x39, 0x3f, 0x3d, 0x33, 0x31, 0x37, 0x35, 0x2b, 0x29, 0x2f, 0x2d, 0x23, 0x21, 0x27, 0x25, 0x5b, 0x59, 0x5f, 0x5d, 0x53, 0x51, 0x57, 0x55, 0x4b, 0x49, 0x4f, 0x4d, 0x43, 0x41, 0x47, 0x45, 0x7b, 0x79, 0x7f, 0x7d, 0x73, 0x71, 0x77, 0x75, 0x6b, 0x69, 0x6f, 0x6d, 0x63, 0x61, 0x67, 0x65, 0x9b, 0x99, 0x9f, 0x9d, 0x93, 0x91, 0x97, 0x95, 0x8b, 0x89, 0x8f, 0x8d, 0x83, 0x81, 0x87, 0x85, 0xbb, 0xb9, 0xbf, 0xbd, 0xb3, 0xb1, 0xb7, 0xb5, 0xab, 0xa9, 0xaf, 0xad, 0xa3, 0xa1, 0xa7, 0xa5, 0xdb, 0xd9, 0xdf, 0xdd, 0xd3, 0xd1, 0xd7, 0xd5, 0xcb, 0xc9, 0xcf, 0xcd, 0xc3, 0xc1, 0xc7, 0xc5, 0xfb, 0xf9, 0xff, 0xfd, 0xf3, 0xf1, 0xf7, 0xf5, 0xeb, 0xe9, 0xef, 0xed, 0xe3, 0xe1, 0xe7, 0xe5 ) gmul3 = ( 0x00, 0x03, 0x06, 0x05, 0x0c, 0x0f, 0x0a, 0x09, 0x18, 0x1b, 0x1e, 0x1d, 0x14, 0x17, 0x12, 0x11, 0x30, 0x33, 0x36, 0x35, 0x3c, 0x3f, 0x3a, 0x39, 0x28, 0x2b, 0x2e, 0x2d, 0x24, 0x27, 0x22, 0x21, 0x60, 0x63, 0x66, 0x65, 0x6c, 0x6f, 0x6a, 0x69, 0x78, 0x7b, 0x7e, 0x7d, 0x74, 0x77, 0x72, 0x71, 0x50, 0x53, 0x56, 0x55, 0x5c, 0x5f, 0x5a, 0x59, 0x48, 0x4b, 0x4e, 0x4d, 0x44, 0x47, 0x42, 0x41, 0xc0, 0xc3, 0xc6, 0xc5, 0xcc, 0xcf, 0xca, 0xc9, 0xd8, 0xdb, 0xde, 0xdd, 0xd4, 0xd7, 0xd2, 0xd1, 0xf0, 0xf3, 0xf6, 0xf5, 0xfc, 0xff, 0xfa, 0xf9, 0xe8, 0xeb, 0xee, 0xed, 0xe4, 0xe7, 0xe2, 0xe1, 0xa0, 0xa3, 0xa6, 0xa5, 0xac, 0xaf, 0xaa, 0xa9, 0xb8, 0xbb, 0xbe, 0xbd, 0xb4, 0xb7, 0xb2, 0xb1, 0x90, 0x93, 0x96, 0x95, 0x9c, 0x9f, 0x9a, 0x99, 0x88, 0x8b, 0x8e, 0x8d, 0x84, 0x87, 0x82, 0x81, 0x9b, 0x98, 0x9d, 0x9e, 0x97, 0x94, 0x91, 0x92, 0x83, 0x80, 0x85, 0x86, 0x8f, 0x8c, 0x89, 0x8a, 0xab, 0xa8, 0xad, 0xae, 0xa7, 0xa4, 0xa1, 0xa2, 0xb3, 0xb0, 0xb5, 0xb6, 0xbf, 0xbc, 0xb9, 0xba, 0xfb, 0xf8, 0xfd, 0xfe, 0xf7, 0xf4, 0xf1, 0xf2, 0xe3, 0xe0, 0xe5, 0xe6, 0xef, 0xec, 0xe9, 0xea, 0xcb, 0xc8, 0xcd, 0xce, 0xc7, 0xc4, 0xc1, 0xc2, 0xd3, 0xd0, 0xd5, 0xd6, 0xdf, 0xdc, 0xd9, 0xda, 0x5b, 0x58, 0x5d, 0x5e, 0x57, 0x54, 0x51, 0x52, 0x43, 0x40, 0x45, 0x46, 0x4f, 0x4c, 0x49, 0x4a, 0x6b, 0x68, 0x6d, 0x6e, 0x67, 0x64, 0x61, 0x62, 0x73, 0x70, 0x75, 0x76, 0x7f, 0x7c, 0x79, 0x7a, 0x3b, 0x38, 0x3d, 0x3e, 0x37, 0x34, 0x31, 0x32, 0x23, 0x20, 0x25, 0x26, 0x2f, 0x2c, 0x29, 0x2a, 0x0b, 0x08, 0x0d, 0x0e, 0x07, 0x04, 0x01, 0x02, 0x13, 0x10, 0x15, 0x16, 0x1f, 0x1c, 0x19, 0x1a ) def __init__(self, key): self._block_size = 16 self._round_keys = self._expand_key([i for i in key]) self._state = [] def _transpose(self, m): return [m[4 * j + i] for i in range(4) for j in range(4)] def _xor(self, a, b): return [x ^ y for x, y in zip(a, b)] def _expand_key(self, key): round_keys = [key] for i in range(10): round_key = [] first = round_keys[i][:4] last = round_keys[i][-4:] last = last[1:] + [last[0]] last = [self.sbox[i] for i in last] round_key.extend(self._xor(self._xor(first, last), [self.rcon[i+1], 0, 0, 0])) for j in range(0, 12, 4): round_key.extend(self._xor(round_key[j:j + 4], round_keys[i][j + 4:j + 8])) round_keys.append(round_key) for i in range(len(round_keys)): round_keys[i] = self._transpose(round_keys[i]) return round_keys def _add_round_key(self, i): self._state = self._xor(self._round_keys[i], self._state) def _mix_columns(self): s = [0] * self._block_size for i in range(4): s[i] = self.gmul2[self._state[i]] ^ self.gmul3[self._state[i + 4]] ^ self._state[i + 8] ^ self._state[i + 12] s[i + 4] = self._state[i] ^ self.gmul2[self._state[i + 4]] ^ self.gmul3[self._state[i + 8]] ^ self._state[i + 12] s[i + 8] = self._state[i] ^ self._state[i + 4] ^ self.gmul2[self._state[i + 8]] ^ self.gmul3[self._state[i + 12]] s[i + 12] = self.gmul3[self._state[i]] ^ self._state[i + 4] ^ self._state[i + 8] ^ self.gmul2[self._state[i + 12]] self._state = s def _shift_rows(self): self._state = [ self._state[0], self._state[1], self._state[2], self._state[3], self._state[5], self._state[6], self._state[7], self._state[4], self._state[10], self._state[11], self._state[8], self._state[9], self._state[15], self._state[12], self._state[13], self._state[14] ] def _sub_bytes(self): self._state = [self.sbox[i] for i in self._state] def _encrypt_block(self): self._add_round_key(0) for i in range(1, 10): self._sub_bytes() self._shift_rows() self._mix_columns() self._add_round_key(i) self._sub_bytes() self._shift_rows() self._add_round_key(10) def encrypt(self, plaintext): ciphertext = b'' self._state = self._transpose([c for c in plaintext]) self._encrypt_block() ciphertext += bytes(bytearray(self._transpose(self._state))) return ciphertext class Challenge: def __init__(self): self.before_input = "Welcome to my military grade encryption service! Try it out by encrypting a message. You can even encrypt the flag, you will not be able to decrypt it anyway...\n" self.aes = AES(urandom(16)) self.nb_encryptions = 0 def challenge(self, your_input): if 'option' not in your_input: return {'error': 'You must specify an option'} if your_input['option'] == 'encrypt_message': message = bytes.fromhex(your_input['message']) if self.nb_encryptions > 0: return {'error': 'You already encrypted a message'} if len(message) != 16: return {'error': 'Message length must be exactly 16 bytes'} self.nb_encryptions += 1 return {'encrypted_message': self.aes.encrypt(message).hex()} elif your_input['option'] == 'encrypt_flag': padding_length = 16 - (len(FLAG) % 16) padded_flag = FLAG + bytes([padding_length]) * padding_length encrypted_flag = b'' for i in range(0, len(padded_flag), 16): encrypted_flag += self.aes.encrypt(padded_flag[i:i + 16]) return {'encrypted_flag': encrypted_flag.hex()} return {'error': 'Unknown action'} listener.start_server(port=13406)