[Cryptography] Long-term security (was Re: ratcheting DH strengths over time)

[Peter Gutmann]

John-Mark Gurney <jmg at funkthat.com> writes:

>Then I thought about it, putting any type of security on it gave the user of
>the device a false sense of security.  There is no way that I could properly
>secure the device from a remote attacker, so I decided that no security was
>the best security...  This would hopefully require the user to use a bastion
>host to access the device..

That's the "false sense of security" bugbear I mentioned in an earlier post.
What about just moving comms to a nonstandard port, or (better) requiring port
knocking, or at least doing something?  Relying on someone else to secure it
means you're going to end up with your totally unprotected device sitting on
the public Internet.  Even just using a nonstandard port will protect against
port-scanning attacks, and then you can add further defences as required, with
each one boxing the attack onto a smaller and smaller attack surface.  This
isn't a "false sense of security", this is actual security that's reducing
your attack surface, even if it's not theoretically perfect cryptographic
security.

Peter.