fyi: bear/enforcer open-source TCPA project

2003-09-08 Thread Sean Smith

The Bear/Enforcer Project
Dartmouth College

http://enforcer.sourceforge.net
http://www.cs.dartmouth.edu/~sws/abstracts/msmw03.shtml

How can you verify that a remote computer is the real thing, doing
the right thing?  High-end secure coprocessors are expensive and
computationally limited; lower-end desktop enhancements like TCPA and
the former Palladium have been mainly limited to Windows and
proprietary development.

In contrast, this code is part of our ongoing effort to use open
source and TCPA to turn ordinary computers into virtual secure
coprocessors---more powerful but less secure than their high-assurance
cousins.

Our current alpha release includes the Linux Enforcer Module, a TCPA
enabled LILO, and a user-level TCPA library.  All source is available
from the SourceForge site.

The Linux Enforcer Module is a Linux Security Module designed to help
improve integrity of a computer running Linux.  The Enforcer provides a
subset of Tripwire-like functionality.  It runs continuously and as
each protected file is opened its SHA1 is calculated and compared to a
previously stored value.

The Enforcer is designed to integrate with TCPA hardware to provide a
secure boot when booted with a TCPA enabled boot loader.  TCPA
hardware can protect secrets and other sensitive data (for example,
the secrets for an encrypted loopback file system) and bind those
secrets to specific software.

When the Enforcer detects a modified file it can, on a per-file basis,
do any combination of the following: deny access to that file, write an
entry in the system log, panic the system, or lock the TCPA hardware.
If the TCPA hardware is locked then a reboot with a un-hacked system is
required to obtain access to the protected secret.

We developed our own TCPA support library concurrently with, but
independently from, IBM's recently announced TCPA library.  Our library
was an initial component of the Enforcer project.  However, our
in-kernel TCPA support and the enforcer-seal tool are derived from
IBM's TCPA code because of its ease of adaptation for in-kernel use.
We plan to use our more complete library for user-level applications.
(IBM's TCPA code and documentation is available from
http://www.research.ibm.com/gsal/tcpa/.)

For more information on our project, see Dartmouth College Technical
Report TR2003-471 available from
http://www.cs.dartmouth.edu/~sws/abstracts/msmw03.shtml

Or contact Omen Wild at the Dartmouth PKI Lab: 
Omen Wild [EMAIL PROTECTED]



-- 
Sean W. Smith, Ph.D. [EMAIL PROTECTED]   
http://www.cs.dartmouth.edu/~sws/   (has ssl link to pgp key)
Department of Computer Science, Dartmouth College, Hanover NH USA




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Re: fyi: bear/enforcer open-source TCPA project

2003-09-09 Thread Sean Smith
 
 How can you verify that a remote computer is the real thing, doing
 the right thing?
 
 You cannot.

Using a high-end secure coprocessor (such as the 4758, but not
with a flawed application) will raise the threshold for the adversary
significantly.

No, there are no absolutes.  But there are things you can do.
 
 The correct security approach is to never give a remote machine
 any data that you don't want an untrusted machine to have. 

So you never buy anything online, or use a medical facility
that uses computers?





-- 
Sean W. Smith, Ph.D. [EMAIL PROTECTED]   
http://www.cs.dartmouth.edu/~sws/   (has ssl link to pgp key)
Department of Computer Science, Dartmouth College, Hanover NH USA




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is secure hardware worth it? (Was: Re: fyi: bear/enforcer open-source TCPA project)

2003-09-11 Thread Sean Smith

Just to clarify... 

I'm NOT saying that any particular piece of secure hardware can never be
broken.   Steve Weingart (the hw security guy for the 4758) used to insist that
there was no such thing as tamper-proof. On the HW level, all you can do is
talk about what defenses you tried, what attacks you anticipated, and what
tests you tried.

What I am saying is that using secure coprocessors---defined loosely, to
encompass this entire family of tokens---can be a useful tool.  Whether one
should use this tool in any given context depends on the context. Are there
better alternatives that don't require the assumption of physical security?
How much flexibility and efficiency do you sacrifice if you go with one of
these alternatives? How dedicated is the adversary?  What happens if a few
boxes get opened?  How much money do you want pay for a device?

Some cases in point: it's not too hard to find folks who've chosen
a fairly weak point on the physical security/cost tradeoff, but still
somehow manage to make a profit.  

Of course his all still leaves unaddressed the fun research questions of how to
build effective coprocessors, and how to design and build applications that
successfully exploit this security foundation.  (Which is some of what I've
been looking into the last few years.)


--Sean

-- 
Sean W. Smith, Ph.D. [EMAIL PROTECTED]   
http://www.cs.dartmouth.edu/~sws/   (has ssl link to pgp key)
Department of Computer Science, Dartmouth College, Hanover NH USA




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Re: PKI Research Workshop '04, CFP

2003-10-22 Thread Sean Smith

(To those people who missed the original comment a year or two back, the first
 PKI workshop required that people use plain passwords for the web-based
 submission system due to the lack of a PKI to handle the task).

Hey, but at least the password was protected by an SSL channel,
which was authenticated by a real certificate signed by one of
the 10^4 trust roots built into your browser :)

---Sean











-- 
Sean W. Smith, Ph.D. [EMAIL PROTECTED]   
http://www.cs.dartmouth.edu/~sws/   (has ssl link to pgp key)
Department of Computer Science, Dartmouth College, Hanover NH USA



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Re: dual-use digital signature vulnerability

2004-07-18 Thread Sean Smith
at the NIST PKI workshop a couple months ago  there were a number
of infrastructure presentations where various entities in the
infrastructure were ...signing random data as part of authentication 
protocol

I believe our paper may have been one of those that Lynn objected to.  
We used the same key for client-side TLS as well as for signing a 
delegation certificate.  However (as we made sure to clarify in the 
revised paper for the final proceedings):

In SSL and TLS, the client isn't signing random data provided by the 
adversary.  Rather, the client is signing a value derived from data 
both the client and server provide as part of the handshake.  I do not 
believe it is feasible for a malicious server to choose its nonces so 
that the resulting signature be coincide with a valid signature on a 
delegation cert the client might have constructed.

(On the other hand, if we're wrong, I'm sure that will be pointed out 
repeatedly here in the next day or two :)

--Sean
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Re: dual-use digital signature vulnerability

2004-07-18 Thread Sean Smith
it isn't sufficient that you show there is some specific 
authentication protocol with unread, random data ... that has 
countermeasures against a dual-use attack ... but you have to 
exhaustively show that the private key has never, ever signed any 
unread random data that failed to contain dual-use countermeasure 
attack.

Why isn't it sufficient?   (Quick: when was the last time anyone on 
this list authenticated by signing unread random data?)

The way the industry is going, user keypairs live in a desktop 
keystore, and are used for very few applications.  I'd bet the vast 
majority of usages are client-side SSL, signing, and encryption.

If this de facto universal usage suite contains exactly one 
authentication protocol that has a built-in countermeasure, then when 
this becomes solid, we're done.

Our energy would be better spent on the real weaknesses: such as the 
ease of getting desktops to just cough up the private key, or to use it 
for client-side SSL without ever informing the user.

And on the real problems: such as using the standard suite to get the 
trust assertions to match the way that trust really flows in the real 
world.

--Sean








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Re: dual-use digital signature vulnerability

2004-07-28 Thread Sean Smith
For what it's worth, last week, I had the chance to eat dinner with 
Carlisle Adams (author of the PoP RFC), and he commented that he didn't 
know of any CA that did PoP any other way than have the client sign 
part of a CRM.

Clearly, this seems to contradict Peter's experience.
I'd REALLY love to see some real numbers here---how many CAs (over how 
many users) do PoP a sane way; how many do it a silly way;  what 
applications people use their keys for, etc.

--Sean
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Re: Any TLS server key compromises?

2004-08-14 Thread Sean Smith
has a TLS server (or client, for that matter) key ever actually been 
compromised?

Hi, Marc!
I don't know about in-the-wild attacks.
However, proof-of-concept attacks:
Server-side: Brumley and Boneh did timing attacks on Apache SSL 
servers---see their Usenix Security paper from 2003.

Client-side: we've done a number of host-based attacks and http-based 
attacks, to steal or borrow use of a user's client-side SSL/TLS key.  
See:

 J. Marchesini, S.W. Smith, M.Zhao.
Keyjacking: The Surprising Insecurity of Client-side SSL
Computers and Security.  To appear, 2004.
http://www.cs.dartmouth.edu/~sws/abstracts/msz04.shtml
--Sean
Sean W. Smith [EMAIL PROTECTED]  www.cs.dartmouth.edu/~sws/
 Asst Prof, Department of Computer Science, Dartmouth College.
 Director, Cybersecurity and Trust Research Center, Institute for 
Security Technology Studies.

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Re: Using TCPA

2005-02-05 Thread Sean Smith
On Feb 4, 2005, at 6:58 AM, Eric Murray wrote:
So a question for the TCPA proponents (or opponents):
how would I do that using TCPA?

check out
enforcer.sourceforge.net
We also had a paper at ACSAC 2004 with some of the apps we've built on 
it.

Two things we've built that haven't made it yet to the sourceforge site:
- an SELinux version
- an OpenSSL engine
--Sean

Sean W. Smith  [EMAIL PROTECTED]  www.cs.dartmouth.edu/~sws/
Hanover, NH USA  (Where the Appalachian Trail crosses the VT-NH border)
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