A 2015 whitepaper on the Symphony Link Protocol states that network level encryption is AES-128, and other places also state that a Diffie-Hellman PKI is used. So, putting this together, my understanding is that DH used to create a shared secret, which is used as a 128 bit AES key. Is that correct? Also, are there options for Symphony Link network encryption in AES-192 or AES-256? Or is that only possible at the application layer?