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One important concept that seems to be missing from the discussion is Sender Stores. Email currently uses a Receiver Stores model. SMTP servers can relay messa
by sounds 12y ago
One important concept that seems to be missing from the discussion is Sender Stores.
Email currently uses a Receiver Stores model. SMTP servers can relay messages, but in almost all cases the message is transmitted directly from the originator's network to the recipient's network. The storage of the message only effectively changes _ownership_ once, even if the message headers say it was forwarded many times.
That makes email a Receiver Stores model: the recipient's network is expected to accept the message at any time and then hold it until the recipient comes to look at it.
Some of the bitcoin messaging protocols propose a Sender Stores model. That is, the message may be transmitted any number of times but the recipient's network is not responsible for long-term storage. The sender's network must be able to provide the message at any time up to the point when the recipient actually looks at the message.
There are some obvious restrictions such as requiring that the message be encrypted with a Diffie-Helman key (negotiated when the message is first transmitted to the receiver's network) to reduce the feasibility of de-duplicating millions of messages. And in order to prevent revealing exactly when the recipient reads the message, the recipient's network doesn't ack the message for a while.
Ultimately all of this is just designed to make bulk email (slightly) more expensive. Spammers run on very, very thin margins. But it doesn't do anything to solve the problem of account termination or blacklisting.
- fanf2 12y agoThe problem with the sender stores model is that the sender does not need to store anything: they just generate the spam message at retrieval time. So it does not actually increase their costs. Spam moves to the notification mechanism that tells receivers that a message is available: this is just as unsolicited as in current junk mail, and needs to contain enough information for the receiver to know if it is worth retrieving the message. All the current spam and anti-spam techniques will apply fairly exactly to these notification messages.
- dredmorbius 12y agoA fair point, but it does require that the sending host persist in its network location (or have continuously updated DNS which reports its present location). Since early recipients of the spam will likely report it, it's fairly likely that subsequent retrieval attempts will find a downed (or sanitized) host, no longer delivering spam. This will reduce the amount of spam actually delivered, and the spammer's production / revenue margins.
- gioele 12y agoWhat you call "Sender Stores" is at the basis of djb's IM2000 that is supposed to replace SMTP and email delivery in general. See http://cr.yp.to/im2000.html http://cr.yp.to/im2000.html and http://en.wikipedia.org/wiki/Internet_Mail_2000 http://en.wikipedia.org/wiki/Internet_Mail_2000
- sounds 12y agoThanks, I hadn't seen that before. End-to-end encryption is needed to increase the load on a spammer as much as possible. Even if the spammer tries to re-generate the message "at retrieval time" the receiver should request retrieval several times (to obfuscate when the message is actually read) and the message should use multiple iterations of a cipher (and possibly HMAC) after an initial DH negotiation, or any other means to increase the cost for a spammer _and_ tie a message to a unique sender for reputation-tracking purposes.