Sync client to establish keys for newly added transports

Write a sync client that establishes transport keys with each contact for any transports that were added more recently than the contact was added.

Subtask of #1802 (closed)

changed due date to July 31, 2021

changed milestone to %Transfer content securely via SD cards and USB memory sticks

added S: in progress Sponsor 6 T: task labels

marked this issue as related to #1802 (closed)

Messages: key, activate, abort

States: await transport, await key, await activate, end

At startup:

• look up (contact id, transport id) for all transport keys in db
• for each contact and each supported transport:
  • if db already contains keys for contact and transport, continue
  • look up session for contact and transport
  • if no session or state == await transport:
    • generate key pair and timestamp
    • add private key to session
    • send key message
    • state = await key
    • save session

When key message is received:

• if transport is supported:
  • look up session for contact and transport
  • if no session and db already contains keys for contact and transport:
    • // when contact was added, we supported the transport but the contact didn't
    • generate key pair and timestamp
    • send key message
    • derive and add rotation keys
    • delete incoming key message
    • send activate message
    • state = await activate
    • save session
  • else if session exists and state == await key:
    • derive and add rotation keys
    • delete private key from session
    • delete incoming key message
    • send activate message
    • state = await activate
    • save session
  • else:
    • delete session and all messages
    • send abort message
• else:
  • state = await transport
  • save session

When activate message is received:

• look up session for contact and transport
• if session exists and state == await activate:
  • activate rotation keys
  • delete local key message
  • state = end
  • save session
• else:
  • delete session and all messages
  • send abort message

When abort message is received:

• look up session for contact and transport
• if session exists:
  • delete session and all messages
  • send abort message

might be nice to put in the extra work to draw the state transition diagram and put it into the wiki where the other clients live.

mentioned in merge request !1472 (merged)

mentioned in merge request !1473 (merged)

mentioned in merge request !1474 (merged)

marked this issue as related to #2069 (closed)

marked this issue as related to #2070 (closed)

added R: fixed label and removed S: in progress label

closed