A pure Go implementation of CRC32A (ITU I.363.5) checksum missing from Golang standard library. Largely based on C implementation found in PHP source files.


package main

import (

func main() {
	b := []byte("123456789")
	sum := crc32a.Checksum(b)
	sumHex := crc32a.ChecksumHex(b)

	fmt.Println(sum)    // 404326908
	fmt.Println(sumHex) // 181989fc


There are four popular implementations of CRC32 of which three are included in Golang standard library. This package provides missing implementation of CRC32A (ITU I.363.5) popularized by bzip2 and PHP. If you're unsure what CRC32 algorithm you're using, calculate checksum for string 123456789 and compare results with the table below.

VariantPerformanceStandard LibraryDataHexSum
CRC32A (ITU I.363.5)31.4 ns/opno123456789181989fc404326908
CRC32B (ITU V.42 / IEEE 802.3)24.0 ns/opyes123456789cbf439263421780262
CRC32C (Castagnoli)15.2 ns/opyes123456789e30692833808858755
CRC32K (Koopman)4534 ns/opyes1234567892d3dd0ae759025838

Note: Unless you're required to use CRC32A for legacy reasons, in general you should choose CRC32B as the most popular and widely implemented CRC32 variation.