Javascript has no way to output data that is then saved to disk.
It will have to be a browser extension or an offline tool (download the encrypted file, decrypt it once you are done).
However I shudder to think about how much malware people are going to get from sites purporting to make "special megaupload decryption tools".
First, there's HTML5 window.saveAs which apparently nobody has implemented. Second, you can always fall back to some swf.
http://stackoverflow.com/questions/2897619/using-html5-javas...
FileSaver.js implements the W3C saveAs() FileSaver interface in browsers that do not natively support it.
No IE support, but what’s the intersection of Mega users and IE users?
Javascript has no way to output data that is then saved to disk.
It will have to be a browser extension or an offline tool (download the encrypted file, decrypt it once you are done).
However I shudder to think about how much malware people are going to get from sites purporting to make "special megaupload decryption tools".