Date: Tue, 2 Oct 2001 19:06:29 -0400
To: Matthew Gaylor <freematt@coil.com>
From: Matthew Gaylor <freematt@coil.com>
Subject: Bruce Schneier's CRYPTO-GRAM SPECIAL ISSUE
Content-Type: text/plain; charset="us-ascii" ; format="flowed"

Date: Sun, 30 Sep 2001 20:10:57 -0500
To: crypto-gram@chaparraltree.com
From: Bruce Schneier <schneier@counterpane.com>
Subject: CRYPTO-GRAM SPECIAL ISSUE, September 30, 2001

    CRYPTO-GRAM

        September 30, 2001

        by Bruce Schneier
  Founder and CTO
       Counterpane Internet Security, Inc.
     schneier@counterpane.com
   <http://www.counterpane.com>


A free monthly newsletter providing summaries, analyses, insights, 
and commentaries on computer and network security.

Back issues are available at 
<http://www.counterpane.com/crypto-gram.html>.  To subscribe, visit 
<http://www.counterpane.com/crypto-gram.html> or send a blank message 
to crypto-gram-subscribe@chaparraltree.com.

Copyright (c) 2001 by Counterpane Internet Security, Inc.


** *** ***** ******* *********** *************

This is a special issue of Crypto-Gram, devoted to the September 11 
terrorist attacks and their aftermath.

Please distribute this issue widely.

In this issue:
      The Attacks
      Airline Security Regulations
      Biometrics in Airports
      Diagnosing Intelligence Failures
      Regulating Cryptography
      Terrorists and Steganography
      News
      Protecting Privacy and Liberty
      How to Help


** *** ***** ******* *********** *************

   The Attacks



Watching the television on September 11, my primary reaction was amazement.

The attacks were amazing in their diabolicalness and audacity: to 
hijack fuel-laden commercial airliners and fly them into buildings, 
killing thousands of innocent civilians.  We'll probably never know 
if the attackers realized that the heat from the jet fuel would melt 
the steel supports and collapse the World Trade Center.  It seems 
probable that they placed advantageous trades on the world's stock 
markets just before the attack.  No one planned for an attack like 
this.  We like to think that human beings don't make plans like this.

I was impressed when al-Qaeda simultaneously bombed two American 
embassies in Africa.  I was more impressed when they blew a 40-foot 
hole in an American warship.  This attack makes those look like minor 
operations.

The attacks were amazing in their complexity.  Estimates are that the 
plan required about 50 people, at least 19 of them willing to die. 
It required training.  It required logistical support.  It required 
coordination.  The sheer scope of the attack seems beyond the 
capability of a terrorist organization.

The attacks rewrote the hijacking rule book.  Responses to hijackings 
are built around this premise: get the plane on the ground so 
negotiations can begin.  That's obsolete now.

They rewrote the terrorism book, too.  Al-Qaeda invented a new type 
of attacker.  Historically, suicide bombers are young, single, 
fanatical, and have nothing to lose.  These people were older and 
more experienced.  They had marketable job skills.  They lived in the 
U.S.: watched television, ate fast food, drank in bars.  One left a 
wife and four children.

It was also a new type of attack.  One of the most difficult things 
about a terrorist operation is getting away.  This attack neatly 
solved that problem.  It also solved the technological problem.  The 
United States spends billions of dollars on remote-controlled 
precision-guided munitions; al-Qaeda just finds morons willing to fly 
planes into skyscrapers.

Finally, the attacks were amazing in their success.  They weren't 
perfect.  We know that 100% of the attempted hijackings were 
successful, and 75% of the hijacked planes successfully hit their 
targets.  We don't know how many planned hijackings were aborted for 
one reason or another.  What's most amazing is that the plan wasn't 
leaked.  No one successfully defected.  No one slipped up and gave 
the plan away.  Al-Qaeda had assets in the U.S. for months, and 
managed to keep the plan secret.  Often law enforcement has been 
lucky here; in this case we weren't.

Rarely do you see an attack that changes the world's conception of 
attack, as these terrorist attacks changed the world's conception of 
what a terrorist attack can do.  Nothing they did was novel, yet the 
attack was completely new.  And our conception of defense must change 
as well.


** *** ***** ******* *********** *************

 Airline Security Regulations



Computer security experts have a lot of expertise that can be applied 
to the real world.  First and foremost, we have well-developed senses 
of what security looks like.  We can tell the difference between real 
security and snake oil.  And the new airport security rules, put in 
place after September 11, look and smell a whole lot like snake oil.

All the warning signs are there: new and unproven security measures, 
no real threat analysis, unsubstantiated security claims.  The ban on 
cutting instruments is a perfect example.  It's a knee-jerk reaction: 
the terrorists used small knives and box cutters, so we must ban 
them.  And nail clippers, nail files, cigarette lighters, scissors 
(even small ones), tweezers, etc.  But why isn't anyone asking the 
real questions: what is the threat, and how does turning an airplane 
into a kindergarten classroom reduce the threat?  If the threat is 
hijacking, then the countermeasure doesn't protect against all the 
myriad of ways people can subdue the pilot and crew.  Hasn't anyone 
heard of karate?  Or broken bottles?  Think about hiding small blades 
inside luggage.  Or composite knives that don't show up on metal 
detectors.

Parked cars now must be 300 feet from airport gates.  Why?  What 
security problem does this solve?  Why doesn't the same problem imply 
that passenger drop-off and pick-up should also be that far away? 
Curbside check-in has been eliminated.  What's the threat that this 
security measure has solved?  Why, if the new threat is hijacking, 
are we suddenly worried about bombs?

The rule limiting concourse access to ticketed passengers is another 
one that confuses me.  What exactly is the threat here?  Hijackers 
have to be on the planes they're trying to hijack to carry out their 
attack, so they have to have tickets.  And anyone can call 
Priceline.com and "name their own price" for concourse access.

Increased inspections -- of luggage, airplanes, airports -- seem like 
a good idea, although it's far from perfect.  The biggest problem 
here is that the inspectors are poorly paid and, for the most part, 
poorly educated and trained.  Other problems include the myriad ways 
to bypass the checkpoints -- numerous studies have found all sorts of 
violations -- and the impossibility of effectively inspecting 
everybody while maintaining the required throughput.  Unidentified 
armed guards on select flights is another mildly effective idea: it's 
a small deterrent, because you never know if one is on the flight you 
want to hijack.

Positive bag matching -- ensuring that a piece of luggage does not 
get loaded on the plane unless its owner boards the plane -- is 
actually a good security measure, but assumes that bombers have 
self-preservation as a guiding force.  It is completely useless 
against suicide bombers.

The worst security measure of them all is the photo ID requirement. 
This solves no security problem I can think of.  It doesn't even 
identify people; any high school student can tell you how to get a 
fake ID.  The requirement for this invasive and ineffective security 
measure is secret; the FAA won't send you the written regulations if 
you ask.  Airlines are actually more stringent about this than the 
FAA requires, because the "security" measure solves a business 
problem for them.

The real point of photo ID requirements is to prevent people from 
reselling tickets.  Nonrefundable tickets used to be regularly 
advertised in the newspaper classifieds.  Ads would read something 
like "Round trip, Boston to Chicago, 11/22 - 11/30, female, $50." 
Since the airlines didn't check ID but could notice gender, any 
female could buy the ticket and fly the route.  Now this doesn't 
work.  The airlines love this; they solved a problem of theirs, and 
got to blame the solution on FAA security requirements.

Airline security measures are primarily designed to give the 
appearance of good security rather than the actuality.  This makes 
sense, once you realize that the airlines' goal isn't so much to make 
the planes hard to hijack, as to make the passengers willing to fly. 
Of course airlines would prefer it if all their flights were 
perfectly safe, but actual hijackings and bombings are rare events 
and they know it.

This is not to say that all airport security is useless, and that 
we'd be better off doing nothing.  All security measures have 
benefits, and all have costs: money, inconvenience, etc.  I would 
like to see some rational analysis of the costs and benefits, so we 
can get the most security for the resources we have.

One basic snake-oil warning sign is the use of self-invented security 
measures, instead of expert-analyzed and time-tested ones.  The 
closest the airlines have to experienced and expert analysis is El 
Al.  Since 1948 they have been operating in and out of the most 
heavily terroristic areas of the planet, with phenomenal success. 
They implement some pretty heavy security measures.  One thing they 
do is have reinforced, locked doors between their airplanes' cockpit 
and the passenger section.  (Notice that this security measure is 1) 
expensive, and 2) not immediately perceptible to the passenger.) 
Another thing they do is place all cargo in decompression chambers 
before takeoff, to trigger bombs set to sense altitude.  (Again, this 
is 1) expensive, and 2) imperceptible, so unattractive to American 
airlines.)  Some of the things El Al does are so intrusive as to be 
unconstitutional in the U.S., but they let you take your pocketknife 
on board with you.

Airline security:
<http://www.time.com/time/covers/1101010924/bsecurity.html>
<http://www.accessatlanta.com/ajc/terrorism/atlanta/0925gun.html>

FAA on new security rules:
<http://www.faa.gov/apa/faq/pr_faq.htm>

A report on the rules' effectiveness:
<http://www.boston.com/dailyglobe2/266/nation/Passengers_say_banned_it 
ems_ha ve_eluded_airport_monitors+.shtml>

El Al's security measures:
<http://news.excite.com/news/ap/010912/18/israel-safe-aviation>
<http://news.excite.com/news/r/010914/07/international-attack-israel-elal-dc>

More thoughts on this topic:
<http://slate.msn.com/HeyWait/01-09-17/HeyWait.asp>
<http://www.tnr.com/100101/easterbrook100101.html>
<http://www.tisc2001.com/newsletters/317.html>

Two secret FAA documents on photo ID requirement, in text and GIF:
<http://www.cs.berkeley.edu/~daw/faa/guid/guid.txt>
<http://www.cs.berkeley.edu/~daw/faa/guid/guid.html>
<http://www.cs.berkeley.edu/~daw/faa/id/id.txt>
<http://www.cs.berkeley.edu/~daw/faa/id/id.html>

Passenger profiling:
<http://www.latimes.com/news/nationworld/nation/la-091501profile.story>

A CATO Institute report: "The Cost of Antiterrorist Rhetoric," 
written well before September 11:
<http://www.cato.org/pubs/regulation/reg19n4e.html>

I don't know if this is a good idea, but at least someone is thinking 
about the problem:
<http://www.zdnet.com/anchordesk/stories/story/0,10738,2812283,00.html>


** *** ***** ******* *********** *************

      Biometrics in Airports



You have to admit, it sounds like a good idea.  Put cameras 
throughout airports and other public congregation areas, and have 
automatic face-recognition software continuously scan the crowd for 
suspected terrorists.  When the software finds one, it alerts the 
authorities, who swoop down and arrest the bastards.  Voila, we're 
safe once again.

Reality is a lot more complicated; it always is.  Biometrics is an 
effective authentication tool, and I've written about it before. 
There are three basic kinds of authentication: something you know 
(password, PIN code, secret handshake), something you have (door key, 
physical ticket into a concert, signet ring), and something you are 
(biometrics).  Good security uses at least two different 
authentication types: an ATM card and a PIN code, computer access 
using both a password and a fingerprint reader, a security badge that 
includes a picture that a guard looks at.  Implemented properly, 
biometrics can be an effective part of an access control system.

I think it would be a great addition to airport security: identifying 
airline and airport personnel such as pilots, maintenance workers, 
etc.  That's a problem biometrics can help solve.  Using biometrics 
to pick terrorists out of crowds is a different kettle of fish.

In the first case (employee identification), the biometric system has 
a straightforward problem: does this biometric belong to the person 
it claims to belong to?  In the latter case (picking terrorists out 
of crowds), the system needs to solve a much harder problem: does 
this biometric belong to anyone in this large database of people? 
The difficulty of the latter problem increases the complexity of the 
identification, and leads to identification failures.

Setting up the system is different for the two applications.  In the 
first case, you can unambiguously know the reference biometric 
belongs to the correct person.  In the latter case, you need to 
continually worry about the integrity of the biometric database. 
What happens if someone is wrongfully included in the database?  What 
kind of right of appeal does he have?

Getting reference biometrics is different, too.  In the first case, 
you can initialize the system with a known, good biometric.  If the 
biometric is face recognition, you can take good pictures of new 
employees when they are hired and enter them into the system. 
Terrorists are unlikely to pose for photo shoots.  You might have a 
grainy picture of a terrorist, taken five years ago from 1000 yards 
away when he had a beard.  Not nearly as useful.

But even if all these technical problems were magically solved, it's 
still very difficult to make this kind of system work.  The hardest 
problem is the false alarms.  To explain why, I'm going to have to 
digress into statistics and explain the base rate fallacy.

Suppose this magically effective face-recognition software is 99.99 
percent accurate.  That is, if someone is a terrorist, there is a 
99.99 percent chance that the software indicates "terrorist," and if 
someone is not a terrorist, there is a 99.99 percent chance that the 
software indicates "non-terrorist."  Assume that one in ten million 
flyers, on average, is a terrorist.  Is the software any good?

No.  The software will generate 1000 false alarms for every one real 
terrorist.  And every false alarm still means that all the security 
people go through all of their security procedures.  Because the 
population of non-terrorists is so much larger than the number of 
terrorists, the test is useless.  This result is counterintuitive and 
surprising, but it is correct.  The false alarms in this kind of 
system render it mostly useless.  It's "The Boy Who Cried Wolf" 
increased 1000-fold.

I say mostly useless, because it would have some positive effect. 
Once in a while, the system would correctly finger a frequent-flyer 
terrorist.  But it's a system that has enormous costs: money to 
install, manpower to run, inconvenience to the millions of people 
incorrectly identified, successful lawsuits by some of those people, 
and a continued erosion of our civil liberties.  And all the false 
alarms will inevitably lead those managing the system to distrust its 
results, leading to sloppiness and potentially costly mistakes. 
Ubiquitous harvesting of biometrics might sound like a good idea, but 
I just don't think it's worth it.

Phil Agre on face-recognition biometrics:
<http://dlis.gseis.ucla.edu/people/pagre/bar-code.html>

My original essay on biometrics:
<http://www.counterpane.com/crypto-gram-9808.html#biometrics>

Face recognition useless in airports:
<http://www.theregister.co.uk/content/4/21916.html>
According to a DARPA study, to detect 90 per cent of terrorists we'd 
need to raise an alarm for one in every three people passing through 
the airport.

A company that is pushing this idea:
<http://www.theregister.co.uk/content/6/21882.html>

A version of this article was published here:
<http://www.extremetech.com/article/0,3396,s%253D1024%2526a%253D15070,00.asp>


** *** ***** ******* *********** *************

 Diagnosing Intelligence Failures



It's clear that U.S. intelligence failed to provide adequate warning 
of the September 11 terrorist attacks, and that the FBI failed to 
prevent the attacks.  It's also clear that there were all sorts of 
indications that the attacks were going to happen, and that there 
were all sorts of things that we could have noticed but didn't.  Some 
have claimed that this was a massive intelligence failure, and that 
we should have known about and prevented the attacks.  I am not 
convinced.

There's a world of difference between intelligence data and 
intelligence information.  In what I am sure is the mother of all 
investigations, the CIA, NSA, and FBI have uncovered all sorts of 
data from their files, data that clearly indicates that an attack was 
being planned.  Maybe it even clearly indicates the nature of the 
attack, or the date.  I'm sure lots of information is there, in 
files, intercepts, computer memory.

Armed with the clarity of hindsight, it's easy to look at all the 
data and point to what's important and relevant.  It's even easy to 
take all that important and relevant data and turn it into 
information.  And it's real easy to take that information and 
construct a picture of what's going on.

It's a lot harder to do before the fact.  Most data is irrelevant, 
and most leads are false ones.  How does anyone know which is the 
important one, that effort should be spent on this specific threat 
and not the thousands of others?

So much data is collected -- the NSA sucks up an almost unimaginable 
quantity of electronic communications, the FBI gets innumerable leads 
and tips, and our allies pass all sorts of information to us -- that 
we can't possibly analyze it all.  Imagine terrorists are hiding 
plans for attacks in the text of books in a large university library; 
you have no idea how many plans there are or where they are, and the 
library expands faster than you can possibly read it.  Deciding what 
to look at is an impossible task, so a lot of good intelligence goes 
unlearned.

We also don't have any context to judge the intelligence effort.  How 
many terrorist attempts have been thwarted in the past year?  How 
many groups are being tracked?  If the CIA, NSA, and FBI succeed, no 
one ever knows.  It's only in failure that they get any recognition.

And it was a failure.  Over the past couple of decades, the U.S. has 
relied more and more on high-tech electronic eavesdropping (SIGINT 
and COMINT) and less and less on old fashioned human intelligence 
(HUMINT).  This only makes the analysis problem worse: too much data 
to look at, and not enough real-world context.  Look at the 
intelligence failures of the past few years: failing to predict 
India's nuclear test, or the attack on the USS Cole, or the bombing 
of the two American embassies in Africa; concentrating on Wen Ho Lee 
to the exclusion of the real spies, like Robert Hanssen.

But whatever the reason, we failed to prevent this terrorist attack. 
In the post mortem, I'm sure there will be changes in the way we 
collect and (most importantly) analyze anti-terrorist data.  But 
calling this a massive intelligence failure is a disservice to those 
who are working to keep our country secure.

Intelligence failure is an overreliance on eavesdropping and not 
enough on human intelligence:
<http://www.sunspot.net/bal-te.intelligence13sep13.story>
<http://www.newscientist.com/news/news.jsp?id=ns99991297>

Another view:
<http://www.wired.com/news/politics/0,1283,46746,00.html>

Too much electronic eavesdropping only makes things harder:
<http://www.wired.com/news/business/0,1367,46817,00.html>

Israel alerted the U.S. about attacks:
<http://www.latimes.com/news/nationworld/nation/la-092001probe.story>
Mostly retracted:
<http://www.latimes.com/news/nationworld/nation/la-092101mossad.story>


** *** ***** ******* *********** *************

      Regulating Cryptography



In the wake of the devastating attacks on New York's World Trade 
Center and the Pentagon, Senator Judd Gregg and other high-ranking 
government officials quickly seized on the opportunity to resurrect 
limits on strong encryption and key escrow systems that ensure 
government access to encrypted messages.

I think this is a bad move.  It will do little to thwart terrorist 
activities, while at the same time significantly reducing the 
security of our own critical infrastructure.  We've been through 
these arguments before, but legislators seem to have short memories. 
Here's why trying to limit cryptography is bad for Internet security.

One, you can't limit the spread of cryptography.  Cryptography is 
mathematics, and you can't ban mathematics.  All you can ban is a set 
of products that use that mathematics, but that is something quite 
different.  Years ago, during the cryptography debates, an 
international crypto survey was completed; it listed almost a 
thousand products with strong cryptography from over a hundred 
countries.  You might be able to control cryptography products in a 
handful of industrial countries, but that won't prevent criminals 
from importing them.  You'd have to ban them in every country, and 
even then it won't be enough.  Any terrorist organization with a 
modicum of skill can write its own cryptography software.  And 
besides, what terrorist is going to pay attention to a legal ban?

Two, any controls on the spread of cryptography hurt more than they 
help.  Cryptography is one of the best security tools we have to 
protect our electronic world from harm: eavesdropping, unauthorized 
access, meddling, denial of service.  Sure, by controlling the spread 
of cryptography you might be able to prevent some terrorist groups 
from using cryptography, but you'll also prevent bankers, hospitals, 
and air-traffic controllers from using it.  (And, remember, the 
terrorists can always get the stuff elsewhere: see my first point.) 
We've got a lot of electronic infrastructure to protect, and we need 
all the cryptography we can get our hands on.  If anything, we need 
to make strong cryptography more prevalent if companies continue to 
put our planet's critical infrastructure online.

Three, key escrow doesn't work.  Short refresher: this is the notion 
that companies should be forced to implement back doors in crypto 
products such that law enforcement, and only law enforcement, can 
peek in and eavesdrop on encrypted messages.  Terrorists and 
criminals won't use it.  (Again, see my first point.)

Key escrow also makes it harder for the good guys to secure the 
important stuff.  All key-escrow systems require the existence of a 
highly sensitive and highly available secret key or collection of 
keys that must be maintained in a secure manner over an extended time 
period.  These systems must make decryption information quickly 
accessible to law enforcement agencies without notice to the key 
owners.  Does anyone really think that we can build this kind of 
system securely?  It would be a security engineering task of 
unbelievable magnitude, and I don't think we have a prayer of getting 
it right.  We can't build a secure operating system, let alone a 
secure computer and secure network.

Stockpiling keys in one place is a huge risk just waiting for attack 
or abuse.  Whose digital security do you trust absolutely and without 
question, to protect every major secret of the nation?  Which 
operating system would you use?  Which firewall?  Which applications? 
As attractive as it may sound, building a workable key-escrow system 
is beyond the current capabilities of computer engineering.

Years ago, a group of colleagues and I wrote a paper outlining why 
key escrow is a bad idea.  The arguments in the paper still stand, 
and I urge everyone to read it.  It's not a particularly technical 
paper, but it lays out all the problems with building a secure, 
effective, scalable key-escrow infrastructure.

The events of September 11 have convinced a lot of people that we 
live in dangerous times, and that we need more security than ever 
before.  They're right; security has been dangerously lax in many 
areas of our society, including cyberspace.  As more and more of our 
nation's critical infrastructure goes digital, we need to recognize 
cryptography as part of the solution and not as part of the problem.

My old "Risks of Key Recovery" paper:
<http://www.counterpane.com/key-escrow.html>

Articles on this topic:
<http://cgi.zdnet.com/slink?140437:8469234>
<http://www.wired.com/news/politics/0,1283,46816,00.html>
<http://www.pcworld.com/news/article/0,aid,62267,00.asp>
<http://www.newscientist.com/news/news.jsp?id=ns99991309>
<http://www.zdnet.com/zdnn/stories/news/0,4586,2814833,00.html>

Al-Qaeda did not use encryption to plan these attacks:
<http://dailynews.yahoo.com/h/nm/20010918/ts/attack_investigation_dc_23.html>

Poll indicates that 72 percent of Americans believe that 
anti-encryption laws would be "somewhat" or "very" helpful in 
preventing a repeat of last week's terrorist attacks on New York's 
World Trade Center and the Pentagon in Washington, D.C.  No 
indication of what percentage actually understood the question.
<http://news.cnet.com/news/0-1005-200-7215723.html?tag=mn_hd>


** *** ***** ******* *********** *************

  Terrorists and Steganography



Guess what?  Al-Qaeda may use steganography.  According to nameless 
"U.S. officials and experts" and "U.S. and foreign officials," 
terrorist groups are "hiding maps and photographs of terrorist 
targets and posting instructions for terrorist activities on sports 
chat rooms, pornographic bulletin boards and other Web sites."

I've written about steganography in the past, and I don't want to 
spend much time retracing old ground.  Simply, steganography is the 
science of hiding messages in messages.  Typically, a message (either 
plaintext or, more cleverly, ciphertext) is encoded as tiny changes 
to the color of the pixels of a digital photograph.  Or in 
imperceptible noise in an audio file.  To the uninitiated observer, 
it's just a picture.  But to the sender and receiver, there's a 
message hiding in there.

It doesn't surprise me that terrorists are using this trick.  The 
very aspects of steganography that make it unsuitable for normal 
corporate use make it ideally suited for terrorist use.  Most 
importantly, it can be used in an electronic dead drop.

If you read the FBI affidavit against Robert Hanssen, you learn how 
Hanssen communicated with his Russian handlers.  They never met, but 
would leave messages, money, and documents for one another in plastic 
bags under a bridge.  Hanssen's handler would leave a signal in a 
public place -- a chalk mark on a mailbox -- to indicate a waiting 
package.  Hanssen would later collect the package.

That's a dead drop.  It has many advantages over a face-to-face 
meeting.  One, the two parties are never seen together.  Two, the two 
parties don't have to coordinate a rendezvous.  Three, and most 
importantly, one party doesn't even have to know who the other one is 
(a definite advantage if one of them is arrested).  Dead drops can be 
used to facilitate completely anonymous, asynchronous communications.

Using steganography to embed a message in a pornographic image and 
posting it to a Usenet newsgroup is the cyberspace equivalent of a 
dead drop.  To everyone else, it's just a picture.  But to the 
receiver, there's a message in there waiting to be extracted.

To make it work in practice, the terrorists would need to set up some 
sort of code.  Just as Hanssen knew to collect his package when he 
saw the chalk mark, a virtual terrorist will need to know to look for 
his message. (He can't be expected to search every picture.)  There 
are lots of ways to communicate a signal: timestamp on the message, 
an uncommon word in the subject line, etc.  Use your imagination 
here; the possibilities are limitless.

The effect is that the sender can transmit a message without ever 
communicating directly with the receiver.  There is no e-mail between 
them, no remote logins, no instant messages.  All that exists is a 
picture posted to a public forum, and then downloaded by anyone 
sufficiently enticed by the subject line (both third parties and the 
intended receiver of the secret message).

So, what's a counter-espionage agency to do?  There are the standard 
ways of finding steganographic messages, most of which involve 
looking for changes in traffic patterns.  If Bin Laden is using 
pornographic images to embed his secret messages, it is unlikely 
these pictures are being taken in Afghanistan.  They're probably 
downloaded from the Web.  If the NSA can keep a database of images 
(wouldn't that be something?), then they can find ones with subtle 
changes in the low-order bits.  If Bin Laden uses the same image to 
transmit multiple messages, the NSA could notice that.  Otherwise, 
there's probably nothing the NSA can do.  Dead drops, both real and 
virtual, can't be prevented.

Why can't businesses use this?  The primary reason is that legitimate 
businesses don't need dead drops.  I remember hearing one company 
talk about a corporation embedding a steganographic message to its 
salespeople in a photo on the corporate Web page.  Why not just send 
an encrypted e-mail?  Because someone might notice the e-mail and 
know that the salespeople all got an encrypted message.  So send a 
message every day: a real message when you need to, and a dummy 
message otherwise.  This is a traffic analysis problem, and there are 
other techniques to solve it.  Steganography just doesn't apply here.

Steganography is good way for terrorist cells to communicate, 
allowing communication without any group knowing the identity of the 
other.  There are other ways to build a dead drop in cyberspace.  A 
spy can sign up for a free, anonymous e-mail account, for example. 
Bin Laden probably uses those too.

News articles:
<http://www.wired.com/news/print/0,1294,41658,00.html>
<http://www.usatoday.com/life/cyber/tech/2001-02-05-binladen.htm>
<http://www.sfgate.com/cgi-bin/article.cgi?file=/gate/archive/2001/09/ 
20/sig intell.DTL>
<http://www.cnn.com/2001/US/09/20/inv.terrorist.search/>
<http://www.washingtonpost.com/wp-dyn/articles/A52687-2001Sep18.html>

My old essay on steganography:
<http://www.counterpane.com/crypto-gram-9810.html#steganography>

Study claims no steganography on eBay:
<http://www.theregister.co.uk/content/4/21829.html>

Detecting steganography on the Internet:
<http://www.citi.umich.edu/techreports/reports/citi-tr-01-11.pdf>

A version of this essay appeared on ZDnet:
<http://www.zdnet.com/zdnn/stories/comment/0,5859,2814256,00.html>
<http://www.msnbc.com/news/633709.asp?0dm=B12MT>


** *** ***** ******* *********** *************

        News



I am not opposed to using force against the terrorists.  I am not 
opposed to going to war -- for retribution, deterrence, and the 
restoration of the social contract -- assuming a suitable enemy can 
be identified.  Occasionally, peace is something you have to fight 
for.  But I think the use of force is far more complicated than most 
people realize.  Our actions are important; messing this up will only 
make things worse.

Written before September 11: A former CIA operative explains why the 
terrorist Usama bin Laden has little to fear from American 
intelligence.
<http://www.theatlantic.com/issues/2001/07/gerecht.htm>
And a Russian soldier discusses why war in Afghanistan will be a nightmare.
<http://www.latimes.com/news/printedition/asection/la-000075191sep19.story>
A British soldier explains the same:
<http://www.sunday-times.co.uk/news/pages/sti/2001/09/23/stiusausa02023.html?>
Lessons from Britain on fighting terrorism:
<http://www.salon.com/news/feature/2001/09/19/fighting_terror/index.html>
1998 Esquire interview with Bin Ladin:
<http://www.esquire.com/features/articles/2001/010913_mfe_binladen_1.html>

Phil Agre's comments on these issues:
<http://commons.somewhere.com/rre/2001/RRE.War.in.a.World.Witho.html>
<http://commons.somewhere.com/rre/2001/RRE.Imagining.the.Next.W.html>

Why technology can't save us:
<http://www.osopinion.com/perl/story/13535.html>

Hactivism exacts revenge for terrorist attacks:
<http://news.cnet.com/news/0-1003-201-7214703-0.html?tag=owv>
FBI reminds everyone that it's illegal:
<http://www.nipc.gov/warnings/advisories/2001/01-020.htm>
<http://www.ananova.com/news/story/sm_400565.html?menu=>

Hackers face life imprisonment under anti-terrorism act:
<http://www.securityfocus.com/news/257>
Especially scary are the "advice or assistance" components.  A 
security consultant could face life imprisonment, without parole, if 
he discovered and publicized a security hole that was later exploited 
by someone else.  After all, without his "advice" about what the hole 
was, the attacker never would have accomplished his hack.

Companies fear cyberterrorism:
<http://cgi.zdnet.com/slink?140433:8469234>
<http://computerworld.com/nlt/1%2C3590%2CNAV65-663_STO63965_NLTSEC%2C00.html>
They're investing in security:
<http://www.washtech.com/news/software/12514-1.html>
<http://www.theregister.co.uk/content/55/21814.html>

Upgrading government computers to fight terrorism:
<http://www.zdnet.com/zdnn/stories/news/0,4586,5096868,00.html>

Risks of cyberterrorism attacks against our electronic infrastructure:
<http://www.businessweek.com/bwdaily/dnflash/sep2001/nf20010918_8931.h 
tm?&_r ef=1732900718>
<http://cgi.zdnet.com/slink?143569:8469234>

Now the complaint is that Bin Laden is NOT using high-tech communications:
<http://www.theregister.co.uk/content/57/21790.html>

Larry Ellison is willing to give away the software to implement a 
national ID card.
<http://www.siliconvalley.com/docs/news/svfront/ellsn092301.htm>
Security problems include: inaccurate information, insiders issuing 
fake cards (this happens with state drivers' licenses), vulnerability 
of the large database, potential privacy abuses, etc.  And, of 
course, no trans-national terrorists would be listed in such a 
system, because they wouldn't be U.S. citizens.  What do you expect 
from a company whose origins are intertwined with the CIA?


** *** ***** ******* *********** *************

  Protecting Privacy and Liberty



Appalled by the recent hijackings, many Americans have declared 
themselves willing to give up civil liberties in the name of 
security.  They've declared it so loudly that this trade-off seems to 
be a fait accompli.  Article after article talks about the balance 
between privacy and security, discussing whether various increases of 
security are worth the privacy and civil-liberty losses.  Rarely do I 
see a discussion about whether this linkage is a valid one.

Security and privacy are not two sides of a teeter-totter.  This 
association is simplistic and largely fallacious.  It's easy and 
fast, but less effective, to increase security by taking away 
liberty.  However, the best ways to increase security are not at the 
expense of privacy and liberty.

It's easy to refute the notion that all security comes at the expense 
of liberty.  Arming pilots, reinforcing cockpit doors, and teaching 
flight attendants karate are all examples of security measures that 
have no effect on individual privacy or liberties.  So are better 
authentication of airport maintenance workers, or dead-man switches 
that force planes to automatically land at the closest airport, or 
armed air marshals traveling on flights.

Liberty-depriving security measures are most often found when system 
designers failed to take security into account from the beginning. 
They're Band-aids, and evidence of bad security planning.  When 
security is designed into a system, it can work without forcing 
people to give up their freedoms.

Here's an example: securing a room.  Option one: convert the room 
into an impregnable vault.  Option two: put locks on the door, bars 
on the windows, and alarm everything.  Option three: don't bother 
securing the room; instead, post a guard in the room who records the 
ID of everyone entering and makes sure they should be allowed in.

Option one is the best, but is unrealistic.  Impregnable vaults just 
don't exist, getting close is prohibitively expensive, and turning a 
room into a vault greatly lessens its usefulness as a room.  Option 
two is the realistic best; combine the strengths of prevention, 
detection, and response to achieve resilient security.  Option three 
is the worst.  It's far more expensive than option two, and the most 
invasive and easiest to defeat of all three options.  It's also a 
sure sign of bad planning; designers built the room, and only then 
realized that they needed security.  Rather then spend the effort 
installing door locks and alarms, they took the easy way out and 
invaded people's privacy.

A more complex example is Internet security.  Preventive 
countermeasures help significantly against script kiddies, but fail 
against smart attackers.  For a couple of years I have advocated 
detection and response to provide security on the Internet.  This 
works; my company catches attackers -- both outside hackers and 
insiders -- all the time.  We do it by monitoring the audit logs of 
network products: firewalls, IDSs, routers, servers, and 
applications.  We don't eavesdrop on legitimate users or read 
traffic.  We don't invade privacy.  We monitor data about data, and 
find abuse that way.  No civil liberties are violated.  It's not 
perfect, but nothing is.  Still, combined with preventive security 
products it is more effective, and more cost-effective, than anything 
else.

The parallels between Internet security and global security are 
strong.  All criminal investigation looks at surveillance records. 
The lowest-tech version of this is questioning witnesses.  In this 
current investigation, the FBI is looking at airport videotapes, 
airline passenger records, flight school class records, financial 
records, etc.  And the better job they can do examining these 
records, the more effective their investigation will be.

There are copycat criminals and terrorists, who do what they've seen 
done before.  To a large extent, this is what the hastily implemented 
security measures have tried to prevent.  And there are the clever 
attackers, who invent new ways to attack people.  This is what we saw 
on September 11.  It's expensive, but we can build security to 
protect against yesterday's attacks.  But we can't guarantee 
protection against tomorrow's attacks: the hacker attack that hasn't 
been invented, or the terrorist attack yet to be conceived.

Demands for even more surveillance miss the point.  The problem is 
not obtaining data, it's deciding which data is worth analyzing and 
then interpreting it.  Everyone already leaves a wide audit trail as 
we go through life, and law enforcement can already access those 
records with search warrants.  The FBI quickly pieced together the 
terrorists' identities and the last few months of their lives, once 
they knew where to look.  If they had thrown up their hands and said 
that they couldn't figure out who did it or how, they might have a 
case for needing more surveillance data.  But they didn't, and they 
don't.

More data can even be counterproductive.  The NSA and the CIA have 
been criticized for relying too much on signals intelligence, and not 
enough on human intelligence.  The East German police collected data 
on four million East Germans, roughly a quarter of their population. 
Yet they did not foresee the peaceful overthrow of the Communist 
government because they invested heavily in data collection instead 
of data interpretation.  We need more intelligence agents squatting 
on the ground in the Middle East arguing the Koran, not sitting in 
Washington arguing about wiretapping laws.

People are willing to give up liberties for vague promises of 
security because they think they have no choice.  What they're not 
being told is that they can have both.  It would require people to 
say no to the FBI's power grab.  It would require us to discard the 
easy answers in favor of thoughtful answers.  It would require 
structuring incentives to improve overall security rather than simply 
decreasing its costs.  Designing security into systems from the 
beginning, instead of tacking it on at the end, would give us the 
security we need, while preserving the civil liberties we hold dear.

Some broad surveillance, in limited circumstances, might be warranted 
as a temporary measure.  But we need to be careful that it remain 
temporary, and that we do not design surveillance into our electronic 
infrastructure.  Thomas Jefferson once said:  "Eternal vigilance is 
the price of liberty."  Historically, liberties have always been a 
casualty of war, but a temporary casualty.  This war -- a war without 
a clear enemy or end condition -- has the potential to turn into a 
permanent state of society.  We need to design our security 
accordingly.

The events of September 11th demonstrated the need for America to 
redesign our public infrastructures for security.  Ignoring this need 
would be an additional tragedy.

Quotes from U.S. government officials on the need to preserve liberty 
during this crisis:
<http://www.epic.org/alert/EPIC_Alert_8.17.html>

Quotes from editorial pages on the same need:
<http://www.epic.org/alert/EPIC_Alert_8.18.html>

Selected editorials:
<http://www.nytimes.com/2001/09/16/weekinreview/16GREE.html>
<http://www.nytimes.com/2001/09/23/opinion/23SUN1.html>
<http://www.freedomforum.org/templates/document.asp?documentID=14924>

Schneier's comments in the UK:
<http://www.theregister.co.uk/content/55/21892.html>

War and liberties:
<http://www.salon.com/tech/feature/2001/09/22/end_of_liberty/index.html>
<http://www.washingtonpost.com/wp-dyn/articles/A21207-2001Sep12.html>
<http://www.wired.com/news/politics/0,1283,47051,00.html>

More on Ashcroft's anti-privacy initiatives:
<http://www.theregister.co.uk/content/6/21854.html>

Editorial cartoon:
<http://www.claybennett.com/pages/latest_08.html>

Terrorists leave a broad electronic trail:
<http://www.wired.com/news/politics/0,1283,46991,00.html>

National Review article from 1998: "Know nothings: U.S. intelligence 
failures stem from too much information, not enough understanding"
<http://www.findarticles.com/m1282/n14_v50/21102283/p1/article.jhtml>

A previous version of this essay appeared in the San Jose Mercury News:
<http://www0.mercurycenter.com/premium/opinion/columns/security27.htm>


** *** ***** ******* *********** *************

       How to Help



How can you help?  Speak about the issues.  Write to your elected 
officials.  Contribute to organizations working on these issues.

This week the United States Congress will act on the most sweeping 
proposal to extend the surveillance authority of the government since 
the end of the Cold War. If you value privacy, there are three steps 
you should take before you open your next email message:

1. Urge your representatives in Congress to protect privacy.
- Call the White House switchboard at 202-224-3121.
- Ask to be connected to the office of your Congressional representative.
- When you are put through, say "May I please speak to the staff 
member who is working on the anti-terrorism legislation?" If that 
person is not available to speak with you, say  "May I please leave a 
message?"
- Briefly explain that you appreciate the efforts of your 
representative to address the challenges brought about by the 
September 11th tragedy, but it is your view that it would be a 
mistake to make any changes in the federal wiretap statute that do 
not respond to "the immediate threat of investigating or preventing 
terrorist acts."

2. Go to the In Defense of Freedom web site and endorse the 
statement:  <http://www.indefenseoffreedom.org>

3. Forward this message to at least five other people.

We have less than 100 hours before Congress acts on legislation that 
will (a) significantly expand the use of Carnivore, (b) make computer 
hacking a form of terrorism, (c) expand electronic surveillance in 
routine criminal investigations, and (d) reduce government 
accountability.

Please act now.

More generally, I expect to see many pieces of legislation that will 
address these matters.  Visit the following Web sites for up-to-date 
information on what is happening and what you can do to help.

The Electronic Privacy Information Center:
<http://www.epic.org>

The Center for Democracy and Technology:
<http://www.cdt.org>

The American Civil Liberties Union:
<http://www.aclu.org>


** *** ***** ******* *********** *************

CRYPTO-GRAM is a free monthly newsletter providing summaries, 
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Please feel free to forward CRYPTO-GRAM to colleagues and friends who 
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CRYPTO-GRAM is written by Bruce Schneier.  Schneier is founder and 
CTO of Counterpane Internet Security Inc., the author of "Secrets and 
Lies" and "Applied Cryptography," and an inventor of the Blowfish, 
Twofish, and Yarrow algorithms.  He is a member of the Advisory Board 
of the Electronic Privacy Information Center (EPIC).  He is a 
frequent writer and lecturer on computer security and cryptography.

Counterpane Internet Security, Inc. is the world leader in Managed 
Security Monitoring.  Counterpane's expert security analysts protect 
networks for Fortune 1000 companies world-wide.

<http://www.counterpane.com/>

Copyright (c) 2001 by Counterpane Internet Security, Inc.


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