From: Sam Smoot <ssmoot@...>
Date: 2006-07-30T00:30:12+09:00
Subject: Re: How to md5 a file?

I use the SHA1 digest for this since it's "more unique", so that gives
me a warm fuzzy. The usage is the same though. Grab a digest, iterate
over the file in chunks, and update the digest. That way it doesn't
matter how large the file is. I do this on multi-gigabyte files and it
still takes less than a minute.