hashes.crc32

CRC32 (Cyclic Redundancy Check 32-bit) Hash Algorithm

This module implements the CRC32 hash algorithm, a non-cryptographic hash function widely used for error detection and data integrity verification.

CRC32 is commonly used in: - ZIP file format for data integrity - Ethernet frame check sequences - PNG image format for chunk verification - Gzip compression

The algorithm uses the IEEE 802.3 polynomial (0xEDB88320 in reversed bit order) and produces a 32-bit hash value.

Note: CRC32 is NOT suitable for cryptographic purposes. It’s designed for error detection, not security. For cryptographic hashing, use SHA-256 or similar.

Reference: - https://en.wikipedia.org/wiki/Cyclic_redundancy_check - https://www.rfc-editor.org/rfc/rfc1952.html (GZIP specification)

Attributes

CRC32_TABLE

Functions

_generate_crc32_table(→ list[int])

Generate the CRC32 lookup table for optimized calculation.

crc32(→ int)

Calculate the CRC32 hash of byte data.

Module Contents

hashes.crc32._generate_crc32_table() → list[int]

Generate the CRC32 lookup table for optimized calculation.

Uses the IEEE 802.3 polynomial: 0xEDB88320 (reversed bit order)

>>> table = _generate_crc32_table()
>>> len(table)
256
>>> hex(table[0])
'0x0'
>>> hex(table[128])
'0xedb88320'
hashes.crc32.crc32(data: bytes) → int

Calculate the CRC32 hash of byte data.

Args:

data: Byte data to calculate the hash for

Returns:

CRC32 hash as a 32-bit integer (0 to 4294967295)

Raises:

TypeError: If data is not of type bytes

>>> crc32(b"Hello World")
1243066710

>>> crc32(b"")
0

>>> crc32(b"The quick brown fox jumps over the lazy dog")
1095738169

>>> crc32(b"a")
3904355907

>>> crc32(b"abc")
891568578

>>> crc32(b"123456789")
3421780262

>>> crc32(b"Python")
2742599054

>>> crc32(b"Algorithms")
3866870335

>>> crc32(b"CRC32")
4128576900

>>> crc32(b"\x00\x00\x00\x00")
558161692

>>> import zlib
>>> test_data = b"Verify with zlib"
>>> crc32(test_data) == zlib.crc32(test_data)
True
hashes.crc32.CRC32_TABLE = []