Overview

Library and CLI tool for calculating and verifying CRC checksums.

Provided Default Configuration(s) of CRC Algorithms:

CRC8	CRC16	CRC32	CRC64
CCITT	CCITT	CRC32	CRC64
AUTOSAR	GSM	AUTOSAR
SAJ1850	PROFIBUS	BZIP2
BLUETOOTH		POSIX
MAXIM-DOW

Requirements

• Python 3.7 and newer

Examples

Calculate crc using the CrcCalculator

from crc import CrcCalculator, Crc8
data = bytes([0, 1, 2, 3, 4, 5 ])
expected_checksum = 0xBC
crc_calculator = CrcCalculator(Crc8.CCITT)

checksum = crc_calculator.calculate_checksum(data)

assert checksum == expected_checksum
assert crc_calculator.verify_checksum(data, expected_checksum)

Speed up the calculation by using a table based CrcCalculator

from crc import CrcCalculator, Crc8

data = bytes([0, 1, 2, 3, 4, 5 ])
expected_checksum = 0xBC
use_table = True
crc_calculator = CrcCalculator(Crc8.CCITT, use_table)

checksum = crc_calculator.calculate_checksum(data)

assert checksum == expected_checksum
assert crc_calculator.verify_checksum(data, expected_checksum)

Create a custom crc configuration for the crc calculation

from crc import CrcCalculator, Configuration

data = bytes([0, 1, 2, 3, 4, 5 ])
expected_checksum = 0xBC

width = 8
poly=0x07
init_value=0x00
final_xor_value=0x00
reverse_input=False
reverse_output=False

configuration = Configuration(width, poly, init_value, final_xor_value, reverse_input, reverse_output)

use_table = True
crc_calculator = CrcCalculator(configuration, use_table)

checksum = crc_calculator.calculate_checksum(data)
assert checksum == expected_checksum
assert crc_calculator.verify_checksum(data, expected_checksum)

Use bare bones crc registers

from crc import Crc8, TableBasedCrcRegister, CrcRegister

data = bytes([0, 1, 2, 3, 4, 5 ])
expected_checksum = 0xBC

reg = CrcRegister(Crc8.CCITT)
table_reg = TableBasedCrcRegister(Crc8.CCITT)

reg.init()
reg.update(data)
assert expected_checksum == reg.digest()

table_reg.init()
table_reg.update(data)
assert expected_checksum == table_reg.digest()

Command line tool

See crc --help

subcommand(s)

table

Subcommand to pre-compute crc lookup tables. See also crc table --help.

checksum

Subcommand to calculate crc checksums of input file(s). See also crc checksum --help.

References & Resources

• A Painless guide to crc error detection algorithms
• Project on Github
• CRC-Catalogue