Re: High Latency Offline Conversations

[Cy]

On Sun, 5 Jul 2020 19:57:20 +0100
Daniel Golle <daniel@makrotopia.org> wrote:

> conversation implements real-time (ie. RTP-like) duplex
> voice-over-IP, ie. "classic" voice-calls using CADET tunnels.

Oh, I'm sorry. I thought it did something useful. Yes, I suppose I'd
have to make my own service then.

> the (early, pre-alpha) attempts of the secushare folks

I don't think they like me much, but I do follow their efforts. I was
thinking more specifically about private message functionality though,
rather than privately owned forums.

> Independently of that, I like your idea of using KSK records for
> offline messaging.

Thanks! I don't think I can take credit for just copying from others
though. Plus I think it's pretty simple and self-evident that if you
already have a shared secret, you can use it as a KSK keyword, to
publish your unsent messages to intermediate nodes, so that your
recipient can get them later even if you're not noline.

> In additional to its body, the message could contain a private key
> which allows the receiver to publish an ACK which only the original
> sender can retrieve. Once the ACK is received by the sender, they
> could stop (re-)publishing the message.

I think it's sufficient to stop republishing, when I reply to a message
you've sent. Though I should be able to provide an empty reply if I'm
not going to reply. Me and the original sender are the only ones who
have the shared session key, so all they have to do is see something
encrypted under it that they didn't create, to know I have acknowledged
their reply.

I'd suggest caution whenever it seems like a good idea to transmit
private keys of any sort.

A better idea might be sending messages that are requests for missing
messages. With message acknowledgement, whoever I'm replying to could
tell when I turned on my computer, by monitoring when an acknowledgement
appeared. But synchronizing a conversation can happen at any time.

Or a conversation could be like a collaborative repository we both are
updating, and we always send each other the CHK of the latest revision,
which contains all our past activity as well as anything I'd like to
add.