Mobile Devices
With this tool you're able to encrypt and decrypt text messages from any internet-enabled computer around the world just by opening the crypt-page at tsxn.com. A link thin and optimal for mobile devices like pda's, windows mobile phones etc. is provided at
Crypt tool thin link for mobile devices: http://www.tsxn.com/crypt
Local Copy
The crypt tool may be downloaded and stored on a usb-stick or any other storage device, even on your pda and then run from there without the need of internet access.
Crypt tool local copy: crypt.zip
After download, unzip and open crypt.htm with any javascript-enabled browser (Internet Explorer, Firefox, etc.).