hashes.crc32
============

.. py:module:: hashes.crc32

.. autoapi-nested-parse::

   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
----------

.. autoapisummary::

   hashes.crc32.CRC32_TABLE


Functions
---------

.. autoapisummary::

   hashes.crc32._generate_crc32_table
   hashes.crc32.crc32


Module Contents
---------------

.. py:function:: _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'


.. py:function:: 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


.. py:data:: CRC32_TABLE
   :value: []