all Python 3binasciifunction

binascii.crc32()

checksums

Computes the CRC-32 of bytes, an unsigned 32-bit number as in ZIP. The second argument continues a running checksum, so a file can be processed in chunks.

Syntax

binascii.crc32(data[, value])

CRC catches accidental corruption, not tampering: crafting data with a chosen checksum is easy, so integrity against an attacker needs hashlib.sha256. It matches zlib.crc32. For a stream pass the running value along: crc = crc32(chunk, crc). In Python 2 the result could be negative, hence '& 0xffffffff' in old code; Python 3 does not need it.

Examples

import binascii
print(binascii.crc32(b'hello world'))  # → 222957957
crc = binascii.crc32(b'hello')
crc = binascii.crc32(b' world', crc)
print(f'{crc:#010x}')  # → 0x0d4a1185

See also

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