How would I send a public key over the size of an individual packet?

[aidenfoxivey]

For sake of argument, assume I am trying to support a cryptographic algorithm that requires key sizes above that which can fit in a single packet. (i.e. 1500 bytes) Given the max size of a packet (to the best of my knowledge) is somewhere around 233 bytes, I definitely need to split it.

Would I need to write my own protobuf spec? I imagine a bodge would be to send them as regular text messages, but that wouldn't be terribly satisfying if it's avoidable.

Please let me know if I need to include more details in my question.