Packet Format
All tapir packets are fixed length (8192 bytes) with the first 2 bytes indicated the actual length of the message,
len
bytes of data, and the rest zero padded:
| len (2 bytes) | data (len bytes) | paddding (8190-len bytes)|
Once encrypted, the entire 8192 byte data packet is encrypted using libsodium secretbox using the standard structure ( note in this case the actual usable size of the data packet is 8190-14 to accommodate the nonce included by secret box)
For information on how the secret key is derived see the authentication protocol