Transphase/transphase/docs/Protocol.md

Transmat protocol description

ver. 0.1

Dramatis Personae:

Relay - Transphase relay Relay Sender - sending party Receiver - receiving party

• Sender creates a low-entropy password, derives a key and a peer_group_id vaule and sends the message containing the peer_group_id to the Relay
• Relay maintains a list of all its peers grouped by their peer_group_id value.
  • If the current message has a new unique peer_group_id, then a new peer group is created.
  • If the current message has a known peer_group_id, then a new peer group is created from it and the party that sent the message (normally the Sender) is added to that group.
• Sender passes the low-entropy password to the Receiver over a different channel (e.g. phone or SSH).
• Receiver derives a key and a peer_group_id value and sends the message containing the peer_group_id to the Relay.
  • This message contains 0 as chunk_number so that the Sender knows that the transfer should start from the very beginning.
• Relay forwards this message to all other peers in the corresponding peer group (that is to the Sender).
• Sender receives this message; sends the encrypted chunk and metadata; and then waits for the Receiver to send a confirmation that it has successfully received the message.
• Relay forwards this message to all other peers in the corresponding peer group (that is to the Receiver).
• Receiver decrypts the payload and writes it to the target file. (TODO: Check chunk hash) Then it sends a confirmation to the Relay. The confirmation contains the incremented number as the chunk_id
  • If this was the last chunk in the transmission, Receiver closes the Websocket connection to the Relay
• Sender receives the confirmation and sends the next encrypted chunk and metadata.
  • If Sender has no more chunks to send, Sender closes the Websocket connection to the Relay