ActionScript File Upload With Encryption on asp.net

Develop an Adobe Flash application which should run on a browser page. It will allow the user to (1) select a file locally on their pc, (2) to enter an encryption key. The application should then encrypt the file using AES within the flash application on the browser and upload the encrypted file to a location on the server. For AES you can use [login to view URL] Technologies:Flash, ActionScript, asp.net v4, vb.net,flex As I am not sure what the best way to do this is, I will agree the details with the worker based on suggestions.