CRC

Calculate CRC checksums, verify CRC checksum, predefined CRC configurations, custom CRC configurations

Documentation: https://nicoretti.github.io/crc
Source Code: https://github.com/Nicoretti/crc

Available CRC Configurations

The library includes a variety of common CRC configurations for convenience. To explore the full range of available CRC configurations, please checkout the configurations section of the documentation. If you need a new configuration to be readily available, consider submitting a PR or raising an issue.

Custom Configurations

If you want to create a custom configuration, you should have the following information available:

width
polynom
init value
final xor value
reversed input
reversed output

In case you only have a name of a specific crc configuration/algorithm and you are unsure what are the specific parameters of it, a look into this crc-catalogue might help.

Note

This library currently only supports bit widths of full bytes 8, 16, 24, 32, ...

Requirements

>= Python 3.8

Installation

pip install crc

Examples

Create a Calculator

Pre defined configurationCustom configuration

from crc import Calculator, Crc8

calculator = Calculator(Crc8.CCITT)

from crc import Calculator, Configuration

config = Configuration(
    width=8,
    poly=0x07,
    init_value=0x00,
    final_xor_value=0x00,
    reverse_input=False,
    reverse_output=False,
)

calculator = Calculator(config)

Calculate a checksum

StandardOptimized for speed

from crc import Calculator, Crc8

expected = 0xBC
data = bytes([0, 1, 2, 3, 4, 5])
calculator = Calculator(Crc8.CCITT)

assert expected == calculator.checksum(data)

from crc import Calculator, Crc8

expected = 0xBC
data = bytes([0, 1, 2, 3, 4, 5])
calculator = Calculator(Crc8.CCITT, optimized=True)

assert expected == calculator.checksum(data)

Verify a checksum

StandardOptimized for speed

from crc import Calculator, Crc8

expected = 0xBC
data = bytes([0, 1, 2, 3, 4, 5])
calculator = Calculator(Crc8.CCITT)

assert calculator.verify(data, expected)

from crc import Calculator, Crc8

expected = 0xBC
data = bytes([0, 1, 2, 3, 4, 5])
calculator = Calculator(Crc8.CCITT, optimized=True)

assert calculator.verify(data, expected)

Supported data types

intbytesbytearrayFileByteIoIterable of bytesByte convertibles

from crc import Calculator, Crc8

expected = 0x20
data = 97
calculator = Calculator(Crc8.CCITT, optimized=True)

assert calculator.checksum(data) == expected

from crc import Calculator, Crc8

expected = 0xF4
data = b"123456789"
calculator = Calculator(Crc8.CCITT, optimized=True)

assert calculator.checksum(data) == expected

from crc import Calculator, Crc8

expected = 0xF4
data = bytearray(b"123456789")
calculator = Calculator(Crc8.CCITT, optimized=True)

assert calculator.checksum(data) == expected

from crc import Calculator, Crc8

expected = 0xF4
calculator = Calculator(Crc8.CCITT, optimized=True)

with open("afile.txt", "rb") as f:
    assert calculator.checksum(f) == expected

import io

from crc import Calculator, Crc8

expected = 0xF4
data = io.ByteIo(b"123456789")
calculator = Calculator(Crc8.CCITT, optimized=True)

assert calculator.checksum(data) == expected

from crc import Calculator, Crc8

expected = 0xF4
calculator = Calculator(Crc8.CCITT, optimized=True)
data = (data for data in [b"12", b"34", b"56", b"78", b"9"])

assert calculator.checksum(data) == expected

from crc import Calculator, Crc8


class ByteConvertible:
    def __init__(self, data):
        self._data = data

    def __bytes__(self):
        return self._data.encode("utf-8")


expected = 0xF4
calculator = Calculator(Crc8.CCITT, optimized=True)
data = ByteConvertible("123456789")

assert calculator.checksum(bytes(data)) == expected

Calculate a checksum with raw registers

RegisterTableBasedRegister

from crc import Crc8, Register

expected = 0xBC
data = bytes([0, 1, 2, 3, 4, 5])
register = Register(Crc8.CCITT)

register.init()
register.update(data)
assert expected == register.digest()

from crc import Crc8, TableBasedRegister

expected = 0xBC
data = bytes([0, 1, 2, 3, 4, 5])
register = TableBasedRegister(Crc8.CCITT)

register.init()
register.update(data)
assert expected == register.digest()

CRC