Monday, June 29, 2020

CRC Information Quick Start

I'm not able to spend much if any time on this lately due to my work in self driving car safety. Here is a quick start for those looking for info.

A tutorial on using CRCs and Checksums (how to apply them, pitfalls, system considerations; not a deep crawl through the math):

A report written for the FAA on CRCs and Checksums (goes with the tutorial)

A web site of "best" CRCs, including:

A summary of "Seven Deadly Sins of CRCs and Checksums":

Maximal length LFSR polynomials:  

My papers on this topic are here:

(There are other posts you might find of interest in the blog as well.)

Also, some FAQ:
  • Can I combine using two small CRCs to get better HD?  Probably not.
    It doesn't work because of error patterns that hit both CRC fields. Maybe it can be done, but every paper I've read has been flawed for this reason and the polynomial searches I ran came up empty handed due to this reason.
  • How does polynomial X perform?
    Please look at the zoo and see if you can find it.  If it is not there I'll add it when I have time if it is a published value.  Be sure to consider there are different notations, which are accounted for in the Zoo.
  • Can you please provide me with free consulting help?
    Sorry, too busy with self driving car safety these days in addition to teaching.  I sometimes answer general interest questions on my blog, but I can only spend a minute or two and it has to be something others will likely find interesting.

Why To Avoid Hash Algorithms If What You Really Need Is A Checksum

Sometimes we hear that someone plans to use a hash function for fault detection instead of a checksum. This is probably not the best idea, b...