RE: Two-Factor Authentication on the Web

["Popowycz, Alex" <Alex.Popowycz () fmr com>]

Lyal,

Would you elaborate as to why SSL is not a reasonable means for transporting authentication credentials?  Properly 
implemented, SSL provides a fair degree of security to the overall authentication transaction, especially if invoked in 
a mutual  fashion (i.e. 2 way SSL).

Additionally, the option of staying with passwords isn't viable with various laws and regulations around the world, 
especially in the financial services sector.

Alex

-----Original Message-----
From: "Lyal Collins" <lyal.collins () key2it com au>
To: "Webappsec Mail List" <webappsec () securityfocus com>
Sent: 7/3/06 6:25 PM
Subject: RE: Two-Factor Authentication on the Web

There has been some excellent discussion on this topic.
However, I think a couple of important factors have been overlooked given
the risk models that are included or assumed in the discussion.
1. Most of the methods assume that the authentications factors (password,
biometric etc) are verified at the host, requiring re-usable authentication
data to be transported across a network.
2. SSL is considered the 'obvious choice' for this transport.

This model is fundamentally flawed - SSL is simply not good enough for this
purpose when used en-masse.  SSH is hardly better, given the key
estabishment method boils down to "do you trusted these 16 hex characters".
PKI and client-side certs are merely client-side password cerification in
untrusted devices/environments.

Since the early nineties, it has been apparent that the better
authentication option is to use client side authentication (i.e data
capture, verification, etc) using a trustable, tamper-evident device, which
them communicates the auth state (i.e. "I am device abc and I have verified
this is entity xyz according to method 123") to the host in a trusted
fashion.

If we are serious about OTP, biometrics, etc we should really be pushing for
either significantly better mechanisms to transport authentication data, or
deploy cheap client-side authentication with trustable carriage of the
authentication data/state and ideally transaction data.

Otherwise, the ethical thing is to tell our employers to stick with
passwords and accept there is a modestly higher risk at a significant cost
saving, or invest in doing it better.

Microsoft's trusted computing platform is a start, but tries to be all
things to all communities of interest, leading to compromises and
difficulties for all.  For strong authentication, the MS model is basically
flawed.

Just my 2-cents worth.

Lyal





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