23 September 2011
Ultra-Security
Date: Fri, 23 Sep 2011 21:08:13 +1000
From: ianG <iang[at]iang.org>
To: cryptography[at]randombit.net
Subject: Re: [cryptography] Nirvana
On 23/09/11 08:33 AM, Nico Williams wrote:
> On Sun, Sep 18, 2011 at 11:22 AM,
M.R.<makrober[at]gmail.com> 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
cryptography[at]randombit.net
http://lists.randombit.net/mailman/listinfo/cryptography
|