Thank you for your assistance!  I had just ignored the "unscaleable" attribute 
in favor of additional explanation.

I would think that  the introduction of a captcha in the registration process 
should handle your concern about flooding the registration engines.  The 
registration is normally done once per creation of a user private/public key 
combination.

From: George Michaelson [mailto:[email protected]]
Sent: Wednesday, September 11, 2013 17:40
To: Karl Malbrain
Subject: Re: [perpass] FW: proposed enhancement to TLS strong authentication 
protocol

no no, I don't think this. sorry its my english. if somebody else from sound 
groundings had said 'palpably wrong' I'd have expected just what you did: ask 
why. the 'unscaleable' hit my funny bone and got a 'this is bullshit, its the I 
dont want it so I'll say something to fudge it response. I just meant that HAD 
somebody said wrong because... or broken because.. I'd not have leapt. But they 
didn't, they just intruded the 'unscaleable' which frankly counts as much as 
'unfashionable'

with mechanisms like UUID registration, (which has come up in APNIC) there is 
an attack model where you flood the registration engine with huge numbers of 
<new> and make it die in a ditch. we have discussed how you make the TCP 
lifetime exponential increase to get to the submit button, or use TLS to bind 
to it, so the cost on the client side is non-trivial, or do captcha or the 
like. none of them are very good. we've been running registry/whois for years, 
and periodically somebody designs a new method of business which demands we 
handle eg 60,000 emails for whois update of their customer more specific, every 
month. we survive fine, but its a challenge. you need to be mindful of this 
kind of non-cost

On Thu, Sep 12, 2013 at 9:30 AM, Karl Malbrain 
<[email protected]<mailto:[email protected]>> wrote:
Of course you've piqued my interest.  In what sense is this palpably broken and 
wrong?

slow:   No, The user's UUID for his public key is only obtained once per TLS 
server on first login.  After that it is stored along with the UUID on the 
server for use in the TLS challenge.

Subvertable:  No, Since the list is read-only, MITM attackers cannot change the 
user's public key to one of their own choosing.  Without the user's private key 
the MITM attacker cannot answer the TLS challenge from the server.  If the MITM 
attacker tries to change the UUID, the server will have no knowledge of the 
bogus client.

From: George Michaelson [mailto:[email protected]<mailto:[email protected]>]
Sent: Wednesday, September 11, 2013 16:21
To: Karl Malbrain

Subject: Re: [perpass] FW: proposed enhancement to TLS strong authentication 
protocol

right. none of this seems to warrant use of the 'unscaleable' word. slow, or 
subvertable, or palpably broken and wrong I can go with, but unscaleable just 
doesn't seem to me to be applicable.

On Thu, Sep 12, 2013 at 9:14 AM, Karl Malbrain 
<[email protected]<mailto:[email protected]>> wrote:
UUID collisions would be handled by the list servers which would silently 
reject posts of user public keys to occupied UUID slots.  User's would 
determine this by noting that a  UUID query doesn't produce their public key, 
and then retry the post with a different UUID.

List servers would communicate among themselves to replicate the list globally.

Karl

From: George Michaelson [mailto:[email protected]<mailto:[email protected]>]
Sent: Wednesday, September 11, 2013 16:08
To: Karl Malbrain
Cc: Phillip Hallam-Baker; Paul Wouters; 
[email protected]<mailto:[email protected]>

Subject: Re: [perpass] FW: proposed enhancement to TLS strong authentication 
protocol

unscaleable is a word which had currency in 16 bit computer days, and possibly 
in 32 bit computers when disks and bandwidth were untenably expensive. I am 
less sure that any enterprise which only has to scale to addressing 2 billion 
people in the next 5-10 years is 'unscaleable' in the real sense of the world.

'seems very inefficient' or 'seems like a problem which will carry its own 
sub-problems' or 'scaling this is a challenge which demands funding and 
eyeballs' are all less direct statements going to the same place.

or do you believe UUID collide, and in fact cannot uniquely identify end 
entities casting the runes to make randoms?

On Thu, Sep 12, 2013 at 5:23 AM, Karl Malbrain 
<[email protected]<mailto:[email protected]>> wrote:
The list is replicated but not centralized per-se. There is only one content. 
Larger servers could maintain their own copy of the replicated list for their 
own usage.

As to the utility of the enhancement, MITM attachments/attacks are precluded by 
strong authentication of both the server and the client.  The specific 
technical problem addressed is the ability of both parties to reliably obtain 
client public keys during TLS negotiation.

From: Phillip Hallam-Baker [mailto:[email protected]<mailto:[email protected]>]
Sent: Wednesday, September 11, 2013 12:16
To: Paul Wouters
Cc: Karl Malbrain; [email protected]<mailto:[email protected]>
Subject: Re: [perpass] FW: proposed enhancement to TLS strong authentication 
protocol



On Wed, Sep 11, 2013 at 2:51 PM, Paul Wouters 
<[email protected]<mailto:[email protected]>> wrote:
On Wed, 11 Sep 2013, Karl Malbrain wrote:
From: Karl Malbrain
Sent: Wednesday, September 11, 2013 11:43
To: 'Theodore Ts'o'
Subject: RE: [perpass] proposed enhancement to TLS strong authentication 
protocol

It's a WORM list.  Users post requests to the list maintainers they trust with 
a GUID to register their public key, and then send this GUID as part of the TLS 
negotiation process.

Seems to me to be basically like an unscalable central version of the TLSA 
record?

https://tools.ietf.org/html/rfc6698

I think it can be decentralized and have been working on an architecture to do 
that for email security.

But it does not really help much for authentication to random Web sites or for 
enterprise use either.



--
Website: http://hallambaker.com/

_______________________________________________
perpass mailing list
[email protected]<mailto:[email protected]>
https://www.ietf.org/mailman/listinfo/perpass



_______________________________________________
perpass mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/perpass

Reply via email to