wrap_key_async
Description:
public async uint8[] wrap_key_async (Object wrapper, Mechanism mechanism, Object wrapped, Cancellable? cancellable) throws Error
  
  Wrap a key into a byte stream.
This call will return immediately and complete asynchronously.
Parameters:
| this | 
           The session to use.  | 
      
| wrapper | 
           The key to use for wrapping.  | 
      
| mechanism | 
           The mechanism to use for wrapping.  | 
      
| wrapped | 
           The key to wrap.  | 
      
| cancellable | 
           Optional cancellation object or null.  | 
      
| callback | 
           Called when the operation completes.  | 
      
| user_data | 
           Data to pass to the callback.  |