codeblog code is freedom — patching my itch

November 18, 2008

md5 lookups for 4 chars and common words

Filed under: Blogging,Debian,Security,Ubuntu,Web — kees @ 8:19 pm

Here’s a fun link. This site appears to have seeded their md5 hash list with all lower case character strings of 4 characters or fewer and many english words (probably from some large dictionaries), and they seem to be adding more as they go. This makes me want to put up an interface to the 7 character alpha-numeric-plus-many-special-chars rainbow table I’ve got. But searching the 500G table for a single hash takes… a while. I’d need to batch it up. Go-go-gadget web 2.0!

© 2008, Kees Cook. This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 License.
CC BY-SA 4.0


  1. Just use Google to search for a MD5 hash, for dictionary words chances are good to get a hit (in some example code etc). Sebastian

    Comment by Sebastian — November 18, 2008 @ 10:24 pm

  2. I will be doing a rewrite of md5oogle soon. Rainbow files I plan to add sometime next year. The database is made up of as you said most 4 letter combinations along with self-generated dictionary, and downloaded dictionary files from multiple languages.

    Comment by Lynk — November 19, 2008 @ 2:48 am

  3. Databases are not optimal data store when the structure of the requests is very predictable. If you only need a way to lookup hash->string, then the simplest way would be to make a folder tree: /a/b/c/d/1/3/f/ and have each end folder contain a strings.txt file with “hashstring” per line. Easy to create and use and VERY fast to look up.

    Comment by Aigars Mahinovs — November 19, 2008 @ 4:41 am

  4. If you want a larger database oh hashes to search, try

    Comment by Brian — September 19, 2009 @ 7:23 pm

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