strEncrypt() and strDecrypt() look useful, though not for checksumming.
another_commander, that link helped a lot.
I have some doubts about the MIT licensing the author uses, as it's based on code that uses BSD license.
I checked the site mentioned, and found http://pajhome.org.uk/crypt/md5/scripts.html
Downloaded the jshash-2.2 zip file , and found the original code .
I'm looking into adapting the MD5 code to Oolite JS now.
Since this could be useful for other oxpers, i'll create a separate oxp for it which will keep the BSD license.
OS : Arch Linux 64-bit - rolling release
OXPs : My user page
I am subscribed to the threads for my oxps, if you need my attention just post in them or send a pm.