- Should the send/receive chains own their keys? (They currently do)
- Maybe instead of Vec<u8> everything can be stored as [u8; 32]?
- X3DH to establish shared secret root key (using the shared session key established by x3dh)
- Implement certificate publication / server setup
- Allow Sha256 or Sha512 as the instantiation (template variable)

### Possible future directions:

- Encrypted headers
    - Signal docs [section 4](https://signal.org/docs/specifications/doubleratchet/#double-ratchet-with-header-encryption)