3esmit
commented
4 years ago I think that is possible to implement push notifications without compromising privacy. It's not necessary to inform user public_key to the server, client can inform anything it wants and contacts can use an additional message just for notifications for that particular user, assuming that the sender knows the notification topic.
Current proposal. public key as notification topics:
- Notification Topics/Channels: User public key
- Users subscribe to the notification service, informing the list of topics they listen.
- Notification service is able to identify when user receives a message.
Advantages: Simple Disadvantages: not private, vulnerable to notification flood
Proposal 1, ephemeral notification topics (contacts only):
- Notification Topics/Channels: When someone adds other in contact, they send a protocol message informing what is the topic they listen for firing "a notification" for that user.
- Users subscribe to the notification service, informing the list of topics they listen.
- The notification topic does not contain the message being sent, just the notification request.
- The notification topic changes from time to time, and might use asymmetric or symmetric encryption.
- Users only receive notifications from users in their contact list.
- "Handshakes" are excluded from the push notification, as they happen while the Status App is open, while users add another user as contact.
Advantages: Safe against flooding, very private Disadvantages: Complex, less scalable,
Proposal 2, public fixed notification topics:
- Notification Topics/Channels: A public channel for each key can be derived by hashing the public key.
- Users subscribe to a "hash of their public key"
- Users are able to derive other's notification topic.
Advantages: Simple, somewhat private Disadvantages: Vulnerable to notification flood
Proposal 3, derived notifications topics:
- Notification Topics/Channels: A public channel for each contact pair, derived from hashing receiver pubkey and sender pubkey
- When adding a contact, users subscribe to everty "hash of their public key+contact private key",
Advantages: Simple, somewhat private Disadvantages: less scalable
oskarth
cammellos
decanus
Specs for the push notification server. Since this is a quite a large document, I would do review in rounds,
First, please provide feedback on the actual protocol, methods etc
After the first phase we can move onto formatting/sections etc and take it from there.