Comment by lvh
7 years ago
Yes! E-mail is fundamentally terribly positioned to do secure messaging. You can use e-mail, or you can have cryptography that works and have people use it, but you can't do both.
7 years ago
Yes! E-mail is fundamentally terribly positioned to do secure messaging. You can use e-mail, or you can have cryptography that works and have people use it, but you can't do both.
> E-mail is fundamentally terribly positioned to do secure messaging
E-mail is fundamentally a way to send a sequence of bytes somewhere (untrusted) so they can be picked up later by someone (trusted).
That’s also literally what Signal is built on so I think you’re overstating the difference.
Secure messaging is much more complex, but here’s a simple example of how that’s not true: TCP is bidirectional and email is one message, fire and forget. That immediately affects your ability to have forward and backward secrecy.
I do not think the OSI model is very useful but you seem to, so let me put it this way: E-mail is bidirectional too just at layer 4 instead of layer 3 (I hope I remembered my layers right!)
E-mail is store-and-forward just like TCP is; how do you think an IP router works? TCP is fully duplex; a tx doesn’t wait behind an rx, exactly like an e-mail reply not waiting behind an e-mail receive. The only difference is that a router will typically use volatile memory to store messages before they are sent but e-mail will typically use disk.
If your security model relies on this difference then your security model is broken. It’s worth noting that Signal does NOT rely on this difference. It relies on participants being mostly online to permit frequent rekeys and not having to retain old keys indefinitely.
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