Subject: [manet] security performance evaluation

From: Bin - Lu <[email-masked]>
Date: Tue, 10 Sep 2002 21:56:31 -0500 (CDT)

Hi,

Is there any standard to evaluate the performance of a security
mechanism for wireless networks, such as:

What detection rate (or false alarm rate) is good / acceptable?
How much delay (or message overhead) imposed by a security mechanism is
acceptable?

Are there any numeric answers (e.g. 10% - 20% or 50 bytes etc.) to these
questions?

I have seen some papers that include security performance evaluation. But
I just don't know why they said - say, a detection rate of 90% was good?

Thanks a lot!

Bin

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From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Wed, 11 Sep 2002 06:54:44 -0600

Hi Bin,

What is an acceptable level of security involves a trade-off between the
cost of implementing security and the possible consequences of not
implementing it.  As you point out, the cost of increased security includes
not only the lower average performance due to overhead, but also the
disruption due to false alarms.  In designing an application, the engineer
attempts to balance these costs.  However, the risks and costs depend on the
application.  

You may be comfortable talking to your mom over an unsecured channel, but
not so comfortable sending your credit card number over that same channel.
A system suitable to manage a taxicab service might not be suitable for a
fire department or police department.

That is to say, the answer to your question would depend on the specific
applications and risks involved.

John Mullen

-----Original Message-----
From: Bin - Lu [mailto:[email-masked]]
Sent: Tuesday, September 10, 2002 8:57 PM
To: [email-masked]
Subject: [manet] security performance evaluation

Hi,

Thanks a lot!

Bin

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Wed, 11 Sep 2002 06:54:44 -0600

Hi Bin,

John Mullen

-----Original Message-----
From: Bin - Lu [mailto:[email-masked]]
Sent: Tuesday, September 10, 2002 8:57 PM
To: [email-masked]
Subject: [manet] security performance evaluation

Hi,

Thanks a lot!

Bin

---

From: "Phil Neumiller" <[email-masked]>
Date: Wed, 11 Sep 2002 09:51:48 -0400

Hi John, Bin,

I agree with you John, however the IETF/IAB clearly has a notion of
what an  "acceptable level of security" is.  In fact they scrutinize all 
RFCs these days for security considerations.   It seems that security 
has been ignored by the MANET WG thus far.   My feeling is that the
"security requirements" for MANET are likely to resemble the requirements
of other working groups and any other network for that matter.

I don't remember where I saw this but someone said "Security is a
PAIN": Privacy/Authentication/Integrity/Non-Repudiation.

Privacy / Confidentiality
-------------------------
<= Likely to be acheived with a symmetric block cipher such as AES.
Probably will not use IPsec. Will likely be done at layer 2 in
most radios used in ad hoc networks.  For example take a look at
IEEE Task Group I for 802.11.   However, key management is
definitely a layer three issue and the real challenge. Most networks use
a PKI to assist with key management and getting a  PKI working on
a MANET is an interesting challenge.  There has been lots of research
on distributed Diffie/Hellman and other group key agreement schemes,
but my feeling is that we need key hierachies for vendors, users, roaming
agreements, AAA, etc.  My hunch is that some sort of distributed KDC
makes more sense than a PKI for MANETs.

Authentication
--------------
<= Can probably start with password based and CHAP like methods.
Digital certificates would be great, but then you need a PKI.  This
does not pose any additional challenge for MANETs other than the
usuall key management issues.

Integrity
---------
<= This is usually solved by using a message authentication code
(MAC) based on a secure hash.  Not particularly challenging for
a MANET just has the key management issue.

Non-Repudiation
--------------
<= Usually solved using Digital certificates + PKI.

PKIX is not widely deployed on the global Internet, so to think
that it will be used widely in ad hoc networks may be wishful
thinking.

To me it seems that a distributed key management scheme is the real
crux of the implementation/engineering problem for MANETs.  Threshold
cryptography offers one possible solution.  Can anybody else think of
other ways to skin the cat?

Best Regards,

Phil

--
Phillip D. Neumiller ([email-masked])
My PGP key can be imported from the following URL: http://pgpkeys.mit.edu
BTW:  It is undecidable whether an arithmetical formula is true!

---

From: "Phil Neumiller" <[email-masked]>
Date: Wed, 11 Sep 2002 09:51:48 -0400

Hi John, Bin,

Authentication
--------------

Integrity
---------

Non-Repudiation
--------------

Best Regards,

Phil

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Wed, 11 Sep 2002 08:23:42 -0600

Hi Phil,

Thanks for the "painful" message.

:-)

I would say "minimal," rather than "acceptable."  That is, a certain amount
of security is needed to assure the system will work properly, but
"acceptable" is still in the venue of the user.

Key management is probably THE issue, but it is clearly an upper level
problem which might even be solved in come cases by a completely independent
means.  In the end, I suspect the role of the MANET protocols will be that
of not getting in the way, rather than actually solving this problem.  One
objective of a MANET protocol is to allow users to automatically join or
leave the net.  Key management will help determine just how easy or
automatic this is.

One way to deal with security is to have all encryption, etc. at level 2 and
key management at level 4 or higher.  That would mean that the MANET
protocol would simply act as if there were no security measures at all.  If
a host attempts to join the net, but is not authenticated at level 2, the
MANET protocol won't even know it is there.  The penalty here is the extra
OH between the protocol and the net.  The advantage is that all aspects of
the MANET management are secure.  Also, the problem of managing security
becomes an independent issue, allowing different users to employ different
security schemes with the same MANET protocol.  This makes it harder for a
usurper to sneak in or disrupt the net.  It also means that MANET protocol
designers don't have to worry about the security.  

Perhaps this is why security is not discussed much here.

John Mullen

-----Original Message-----
From: Phil Neumiller [mailto:[email-masked]]
Sent: Wednesday, September 11, 2002 7:52 AM
To: [email-masked]
Cc: Mullen, John P. (Contractor); [email-masked]
Subject: RE: [manet] security performance evaluation

Hi John, Bin,

Authentication
--------------

Integrity
---------

Non-Repudiation
--------------

Best Regards,

Phil

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Wed, 11 Sep 2002 08:23:42 -0600

Hi Phil,

:-)

John Mullen

-----Original Message-----
From: Phil Neumiller [mailto:[email-masked]]
Sent: Wednesday, September 11, 2002 7:52 AM
To: [email-masked]
Cc: Mullen, John P. (Contractor); [email-masked]
Subject: RE: [manet] security performance evaluation

Hi John, Bin,

Authentication
--------------

Integrity
---------

Non-Repudiation
--------------

Best Regards,

Phil

---

From: Phillip Neumiller <[email-masked]>
Date: Wed, 11 Sep 2002 12:07:22 -0400

Just some follow-on ramblings...

I hear one of the security hawks swooping down on you John.  Before they
get here I will point out some reasons WHY MANET may need to be at least
partially involved in security.

Encryption at L2 is one thing.  Mode of operations is another.
We know that privacy and authentication are provided by OCB-AES as will
likely be used in IEEE 802 series products.  

The problem with this WEP fix is ad hoc mode has not been addressed 
adequatley (specifically the key distribution problem).  So I am not
sure that we can just say "son-of-WEP" fixes all of our problems for
802 type devices.  

If the whole L2 is encrypted, then only devices with a shared secret can
see each others messages, i.e. CSMA carrier sense becomes broken, 
MACA becomes broken, etc.   How does one gracefully acquire a key when
joining a group without credentials?  I think there are tons of 
issues here, the biggest one is probably accounting.  

Ad hoc networks will be most useful when they are used to extend the
global Internet, i.e. where one or more of the nodes provide backhaul
to the big I.  Aah, that is the key, then there is connectivity to 
Infrastructure and that opens doors to using a certificate authority,
IEEE 802.1X (EAP/LEAP) / Radius and a PKI.  Is this a MANET topic?

Commercializing MANETs will require security and there are definite
issues to address.  Mobility, handoff, roaming, and Internet access
themselves are billable services irrespective of the underlying 
network topology.  So addressing them in MANETs will be important
if we ever hope to make them commercially successful.  I would love
to see some standardization effort here in the MANET group.

Regards...
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From: Phillip Neumiller <[email-masked]>
Date: Wed, 11 Sep 2002 12:07:22 -0400

Regards...

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Wed, 11 Sep 2002 10:27:00 -0600

Hi Phillip,

Well, security is important.  However, to be effective, the key elements of
the security system need to be kept secret.  Any detail that becomes public
reduces the difficulty of the usurper's task.  (Remember the Allies were
able to decrypt the "unbreakable" Enigma code, in part, because German
operators got sloppy and did not change keys often enough.)  

:-)

This is an open forum, which means nothing discussed here is secret.

However, it is important that the MANET protocols do not complicate
security, which is why I say the main task in this group is to come up with
protocols that do not get in the way of security.

One approach is to make a public dummy version of the security system that
interacts with the protocol, but does not reveal its inner secrets.  That
would have to be designed by the security experts and signed off by the
security managers who would have to be convinced that revealing this much
wont lead to a security breach in the future.  

....

Well, it was an idea.

:-)

John Mullen

-----Original Message-----
From: Phillip Neumiller [mailto:[email-masked]]
Sent: Wednesday, September 11, 2002 10:07 AM
To: Mullen, John P. (Contractor); Phillip Neumiller; [email-masked]
Subject: RE: [manet] security performance evaluation

Regards...

---

From: Phillip Neumiller <[email-masked]>
Date: Wed, 11 Sep 2002 12:55:15 -0400

Hi John,

One final point and then I will let somebody else jump in...

You said:
"Well, security is important.  However, to be effective, the key elements of
the security system need to be kept secret. "

I want to make it clear that this is NOT my position.  To my best
understanding,
the only thing that must be kept private is the private key in modern day
crypto
algorithms.  The implementation must be completely "white box" so that it
can
be cryptanalyzed prior to mass deployment.  That is precisely WHY I want to
see MANET RFCs covering security.  I suppose I should find some time to
start
off a MANET security requirements and issues draft. :-)

Regards,

Phil

---

From: "Michael E. Locasto" <[email-masked]>
Date: Wed, 11 Sep 2002 12:57:36 -0400 (EDT)

Hello,

> the security system need to be kept secret.

Are you talking about cryptographic keys or the essential mechanism
behind the security system when you say 'key elements'?

If the latter, why should the security of the system should be based on
the secrecy of a mechanism? Obviously, in crypto, you shouldn't broadcast
your secret key [or make it easily guessable :-)], but the mechanism
itself need not be secret if it is strong enough.

I think the more people that look at and debug/analyze a mechanism, the
better, and working security in on the ground floor as an integral part of
the protocols will establish a higher level of confidence than attempting
to tie some other mechanism on top.

So how do we begin to standardize the approach to security in MANET?

Regards,
Michael Locasto

---

From: Phillip Neumiller <[email-masked]>
Date: Wed, 11 Sep 2002 12:55:15 -0400

Hi John,

You said:

Regards,

Phil

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Wed, 11 Sep 2002 11:38:19 -0600

Hi Miguel,

I agree with you.

The problem is that "security" means different things in different
situations.

In police, military, etc. each potential user would probably gain the key,
etc. through some sort of physical transfer.  In these systems, pre
authorized users join and leave MANETS, but strangers are not welcome.  All
aspects of the system would probably be encrypted to provide security
against all sorts of stuff.

In other applications, it might be enough to encrypt individual messages, as
needed, to provide privacy.  We have something like this on the Internet
now.

There are other aspects of network security.  How do we prevent attempts (or
accidents) that might disable the network?  If A thinks he is talking to B,
how do we make sure that is the case?  How can A and B be sure C isn't
eavesdropping?  If things are billable, how do we prevent fraud or theft?  

Certainly, public discussion of the architecture would lead to a superior
product, but at some point you need to decide if further openness is good or
bad.  It is similar the discussion of whether to patent or use a trade
secret.  A patent protects your rights, but reveals your secrets.  On the
other hand, a trade secret is provides less legal protection, but less is
revealed.  As a rule of thumb, if your secrets can be discovered by reverse
engineering, then it is best to patent, but if it would be difficult or
impossible to reverse engineer the product, the trade secret is usually the
way to go.

So, I guess, the dividing line would be whether or not the particular
element would be evident to anyone observing the system.  If it is, you
might as well make it public.  However, if the element is not evident, it
might be better to keep that detail on the QT.

John Mullen

-----Original Message-----
From: Miguel Sanchez [mailto:[email-masked]]
Sent: Wednesday, September 11, 2002 11:09 AM
To: Mullen, John P. (Contractor)
Cc: Phillip Neumiller; [email-masked]
Subject: Re: [manet] security performance evaluation

Hi John,

I may be missing something but it seems to me that ad-hoc networks are 
built by collaboration among network nodes. In some cases these nodes 
are not trusted to each other (ok, maybe not the case for a set of 
military gadgets).

Without any previous contact, unknown nodes should be considered, either 
safe or unsafe, by default. In the first case you are creating a 
friendly system even for the bad behaved nodes, in the second case it 
can be complex and difficult to join, but you may have a safer network.

The problem is that some ad-hoc networks are tightly associated to a 
high rate of node joins/leaves.

If we are using a private key system, like WEP, we need a central 
authority to create and to hand out the key. And we need the users to 
contact this authority by other means to get the key before they can 
join the ad-hoc network. This could work if all the users may have a 
simple and easy way to get the key, as far as they be really careful 
about keeping the key secret. Is this a typical ad-hoc scenario? I think 
mostly not with, maybe, the exception of military systems (and for them 
is what spies are for).

I think that a strong security system will kill the idea of a 
collaborative network. However I will be glad to be proved wrong, given 
we seem to agree security is an desirable property of an ad-hoc network. 
It is just I have the feeling that most of the security will be obtained 
by making a flat, peer-to-peer, ad-hoc network into a hierachical and 
somehow centralized system (you need a common security database).

I am with Phil about the "white box" approach to security design. (As 
you mention, Enigma code was cracked, as it has happened with WEP ... 
more recently). Of course this approach is not a guaratee of a 
fault-free system.

Regards,

Miguel Sanchez
Politechnic University of Valencia, Spain

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Wed, 11 Sep 2002 11:38:19 -0600

Hi Miguel,

I agree with you.

John Mullen

-----Original Message-----
From: Miguel Sanchez [mailto:[email-masked]]
Sent: Wednesday, September 11, 2002 11:09 AM
To: Mullen, John P. (Contractor)
Cc: Phillip Neumiller; [email-masked]
Subject: Re: [manet] security performance evaluation

Hi John,

Regards,

Miguel Sanchez