71 lines
1.9 KiB
Python
71 lines
1.9 KiB
Python
import dataclasses
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from typing import Literal
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import bitstring
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# Reference for H10301 card format:
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# https://www.hidglobal.com/sites/default/files/hid-understanding_card_data_formats-wp-en.pdf
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class InvalidHexCode(Exception):
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pass
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class Not26Bit(InvalidHexCode):
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def __init__(self, bits: bitstring.Bits) -> None:
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super().__init__(f"Card number > 26 bits [{bits.hex}]")
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class InvalidParity(InvalidHexCode):
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def __init__(self, bits: bitstring.Bits, even_odd: Literal["even", "odd"]) -> None:
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super().__init__(f"Bad {even_odd} parity [{bits.hex}]")
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@dataclasses.dataclass(frozen=True)
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class Credential:
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bits: bitstring.Bits
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@staticmethod
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def even_parity(bits: bitstring.Bits) -> bool:
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return bool(bits[7:19].count(1) % 2)
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@staticmethod
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def odd_parity(bits: bitstring.Bits) -> bool:
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return (bits[19:31].count(1) % 2) == 0
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@classmethod
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def from_code(cls, facility: int, card_number: int) -> "Credential":
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bits = bitstring.pack(
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"0b000000, 0b0, uint:8=facility, uint:16=card_number, 0b0",
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facility=facility,
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card_number=card_number,
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)
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bits[6] = cls.even_parity(bits)
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bits[31] = cls.odd_parity(bits)
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return cls(bitstring.Bits(bits))
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@classmethod
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def from_hex(cls, hex_code: str) -> "Credential":
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bits = bitstring.Bits(hex=hex_code)
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if bits[:6].any(1):
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raise Not26Bit(bits)
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if bits[6] != cls.even_parity(bits):
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raise InvalidParity(bits, "even")
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if bits[31] != (cls.odd_parity(bits)):
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raise InvalidParity(bits, "odd")
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return cls(bits)
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@property
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def facility_code(self) -> int:
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return self.bits[7:15].uint
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@property
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def card_number(self) -> int:
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return self.bits[15:31].uint
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@property
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def hex(self) -> str:
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return self.bits.hex.upper()
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