php - What is the difference between crc32 and crc32b?

Question

Apparently the PHP function hash() can be called with the algorithms crc32 and crc32b? What is the difference between them?

Answer 1

Two different algorithms. CRC32b is an implementation of the consistency algorithm defined here, whereas CRC32 is the frame check sequence defined here. They're different things, though the differences are not often big.

One way to check this:

<?php
echo hash("crc32", __FILE__)."<br/>";
echo hash("crc32b", __FILE__); ?>

Due to their similarity, the starting hex values will be relatively similar.