Adler32 is a checksum algorithm, An Adler-32 checksum is obtained by calculating two 16-bit checksums \(s1\) and \(s2\) and concatenating their bits into a 32-bit integer. \(s1\) is the sum of all bytes in the stream plus one, and \(s2\) is the sum of the individual values of \(s1\) from each step. (from wiki)
The Adler32 algorithm is defined in `RFC 1950`_ and `Wiki Adler32`_.