On 23/09/11 08:33 AM, Nico Williams wrote:
On Sun, Sep 18, 2011 at 11:22 AM, M.R.<[email protected]> wrote:
In your view then, is the alternative at all a public key based
crypto system? If yes, is it SSH (or SSH-like) "trust on first
contact" or something else?
It could vary.
For low-security applications, like blog comments, yes, leap-of-faith will do.
For a medium-security application, like shopping (where systems like
credit card fraud protection render the risk to the user low),
security bootstrapped from leap-of-faith + trust-building or trusted
third parties will probably do.
I would go TOFU -- trust-on-first-use -- here alone, but replaceable by
certs signed by other parties, in a compatible fashion.
I don't understand the leap-of-faith metaphor. It seems to me that
trusting a CA is a leap of faith given that we have to trust all of
them, and we know next to nothing about them. Bad risk analysis there,
because we've outsourced it to unknown parties, via other unknown parties.
Whereas when we are doing the TOFU mechanism, we can incorporate all of
our local knowledge and decide whether there is any risk in dealing with
this merchant. Good risk analysis.
For high-security applications (like banking) you'll generally want to
bootstrap security via something else, either an off-line interaction,
or a trusted third party that can authenticate relatively few peers to
you (and thus is probably more trustworthy w.r.t. verification of your
peer's credentials).
There is another level of security above that which I guess we'll have
to call ultra-security [0]. This is for real time transactions (payment
systems or trading) and/or high values, and/or natsec things.
In ultra-sec, we'd download a client securely the supplier, and put it
on to a single purpose machine.
iang
[0] Which I call high security. Banking I generally call medium
security ... anything using web browsers isn't really serious IMHO.
_______________________________________________
cryptography mailing list
[email protected]
http://lists.randombit.net/mailman/listinfo/cryptography
