title: Secure Javascript encryption library?
body: <p>I'm searching a javascript library that offers secure encryption. The client has to generate a key and all data uploaded to the server is encrypted, all data downloaded is decrypted. I need an authenticated encryption scheme, just CTR or CBC isn't enough.</p>
  
  <p>I heard about sjcl, but it seems that sjcl only can encrypt the whole data at once. I didn't find a way to encrypt the data blockwise. Because the uploaded files can be very large, this approach isn't feasible. I need something like the java crypto interface with two methods update() and final().</p>
  
  <p>I found the nodeJS crypto library that seems to do what I need, but I don't know how to use it on browser side.</p>
  
  <p>I found google crypto-js, but this library doesn't seem to offer authenticated encryption but only the standard modes.</p>
  
  <p>Is there a way to encrypt data blockwise with sjcl? To use the nodeJS crypto library on browser side? To use authenticated encryption with crypto-js? Or is there another secure javascript library that offers what I need?</p>