On: jsSHA - A JavaScript Implementation Of The Entire Family Of SHA Hashes

[hdevalence]

There's a nice article here:

http://www.matasano.com/articles/javascript-cryptography/

that explains some of the issues with JavaScript-based cryptosystems.

[saurik → hdevalence]

Note: these arguments only apply to JavaScript in a browser (and at that point, apply to virtually any client-side system attempting to somehow protect information from being snooped on by the server that dynamically provides the code to execute on the client <- an idea that should have been preposterous from the start ;P).