nc misc.chal.csaw.io 4239
解法
首先連上去會看到這個：
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8-1-1 even parity. Respond with '1' if you got the byte, '0' to retransmit. 00110111001
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用關鍵字 serial parity 查了一下可以找到 serial communication data format（參考：這張圖）
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+-------+-------+-------+-------+-------+-------+-------+-------+-------+--------+------+ | start | bit 0 | bit 1 | bit 2 | bit 3 | bit 4 | bit 5 | bit 6 | bit 7 | parity | stop | +-------+-------+-------+-------+-------+-------+-------+-------+-------+--------+------+
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去頭去尾，中間看加總是不是偶數，是就記錄下來並送出 1 收下一段資料，不是就代表資料有問題，送出 0 來重新收取這段資料。
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from pwn import * context.log_level = logging.DEBUG r = remote('misc.chal.csaw.io', 4239) series = [] r.recvline() try: while True: data = r.recvline().strip()[1:-1] if sum(map(int, list(data))) % 2 == 0: series.append(data[:-1]) r.sendline('1') else: r.sendline('0') except Exception as e: pass print ''.join([chr(int(x, 2)) for x in series])
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Flag:flag{@[email protected]@_circuit-term1nating_3quipment}
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