HTML5 Client Side Data Encryption - What are my options?

Question

I am working on a EDIT: mobile web app which displays some sensitive information and requires a login which stores the members username and password in a HT

Answer 1

I have to say if your creating a session data 1 is that not,- stored on the server not client side thus no one sees the session data or at least it should be done that way via asp, or php, ect so have the app require internet and retrieve the info from a web server and don't store it on the client side. 2 if this does deal with client side like dealing with streaming a video, or images or you have to create some files on the client side storing the key on the clients mobile device is the only way. Thus either have the key with a short ttl to decrypt the data, the key given through some form of authentication or certificate, or a key installed from your main office and encrypt the device in case they loose it. I not found and encrypt function I like to suggest yet for you.