Adler 32 Hash

Adler-32 Hash / Checksum Generator

Adler-32 is an algorithm for generating or calculating checksum. The meaning of the name can be separated into two part, Adler and 32.

Adler because it was invented by Mark Adler in 1995.

32 because the final checksum is calculated from two 16 bit checksums. Two checksums combined into one / single 32 bit checksum.

Adler-32 is a modification of the Fletcher checksum. This checksum also designed and widely used on Zlib compression. Fun fact, the creator of this checksum (Mark Adler), also written part of Zlib code.

If Adler-32 is compared to cyclic redundancy check (crc) from the same length, Adler-32 is faster, but less reliable.

And in terms of reliability, Adler-32 sits between Fletcher-16 and Fletcher-32, with Fletcher-32 have better reliability that Adler-32.

What is Checksum or Hash Reliability?

Reliability for checksum / hash can intrepeted as the probability that two different input can generate the same hash / checksum. This often called hash collision