The Risks Digest

The RISKS Digest

Forum on Risks to the Public in Computers and Related Systems

ACM Committee on Computers and Public Policy, Peter G. Neumann, moderator

Volume 19 Issue 09

Thursday 17 April 1997

Contents

o Why Bre-X crashed the Toronto Stock Exchange
Dave Wortman
o "Big Glitch Hits MSN E-mail"
PGN
o "Heading off emergencies in large electric grids"
IEEE Spectrum via PGN
o "My Hairiest Bug War Stories"
CACM via PGN
o The risks of not using your own security measures [name withheld by request]
o Daylight savings change problem
Steve Doig
o Using GPS as your time standard
Bernard Lyons
o Re: Fake "PGP CRACKED" message lures users into trap
Fred Cohen
o Re: DES Challenge risks
Thomas Koenig
o Re: Social Security--the other side
Carey Tyler Schug
o Re: YAAXF: Yet Another ActiveX Flaw
Russ Cooper
o They fixed one! 11-digit dialing in San Diego
Mark Seecof
o Re: Risks of Mail Merge for Ontario NDP
Mark Connolly
o Daylight Time and UTC
Maggie Iaquinto
o Re: More on GMT vs BST: RS6000
Andrew Yeomans
o Re: GMT, BST, UTC and all
Ian Miller
Bernard Lyons
Ian Stephens
o "Network Security" by Kaufman/Perlman/Speciner
Rob Slade
o Info on RISKS (comp.risks)

Why Bre-X crashed the Toronto Stock Exchange

Dave Wortman <dw@pdp1.sys.toronto.edu>
Wed, 16 Apr 1997 11:05:17 -0400
Previously undiscovered bugs in a legacy software system and record high
trading volumes in one stock are being blamed for crashes that stopped
trading on the Toronto Stock Exchange several times in the last few days.

The stock is question is Bre-X Minerals Ltd. Its price is in free fall due
to alleged misrepresentations concerning assay results for their large gold
discovery in Indonesia.

Although the Toronto Stock Exchange (TSE) is able to handle large trading
volumes (e.g. 23.2 billion shares/year), the frantic buying and selling of
Bre-X shares exceeded the normal volume for a single stock by a couple
orders of magnitude leading to memory and system congestion problems.

In "TSE speak", the active set of buy and sell orders for a particular stock
is a "book".  Under normal conditions a book contains 200 .. 300 orders.
The largest book size encountered before Bre-X was around 1600 orders.  The
Bre-X book was averaging 2,500 orders with peaks to around 4,500 orders.

The TSE trading system is estimated at 3,000,000 LOC (language unspecified).
The article describes the code as poorly documented and heavily modified.
The software is designed so that when it tries to execute a single order
(buy or sell transaction), it reads the entire book for the stock into main
memory (probably to match buy and sell orders).  Normally this isn't a
problem but the size of the Bre-X book caused memory contention/overload
problems that apparently crashed the system.  This problem was fixed by
adding more memory to the system.

Subsequent attempts to run the system exposed another bug in the legacy
software. There is apparently a memory leak that occurs when an order is
canceled.  The memory for the order (or possible the entire book) isn't
released properly and eventually the system strangles for lack to available
memory. The very high trading volume in Bre-X caused a much higher than
normal number of cancelled orders. The TSE is working on a solution to this
problem and as an interim measure is carefully controlling trading in Bre-X.

These problems hadn't surfaced in 20 years of operation because the order
books had never been big enough and the trading in one stock volatile enough
to trigger the memory problems.

  [Source: Abstracted from a very well written article by Geoffrey Rowan in
  the *Toronto Globe and Mail*, 12 Apr 1997]


"Big Glitch Hits MSN E-mail"

"Peter G. Neumann" <neumann@chiron.csl.sri.com>
Thu, 17 Apr 97 12:11:17 PDT
On Monday, 14 Apr 1997, as a result of greatly increasing volume of e-mail
traffic, two Microsoft MSN servers bellied up -- one for users with logon
names beginning with C through E, the other with names beginning with T
through Z.  After two days of persistent reboots, further crashes, and lots
of customer complaints, Microsoft finally shut down the entire MSN e-mail
service on 16 Apr 1997 for a day or two, to increase storage capacity.  This
affects all 2.5 million customers.  [Source: an article by Julia Angwin,
*San Francisco Chronicle*, 17 Apr 1997, D1]


"Heading off emergencies in large electric grids" (*IEEE Spectrum*)

"Peter G. Neumann" <neumann@chiron.csl.sri.com>
Wed, 16 Apr 97 17:19:22 PDT
*IEEE Spectrum*, April 1997 (pp.43-47) includes a marvelous article by
Nickolai Grudinin and Ilya Roytelman of Siemens Power Systems Control, with
the title as in the "Subject:" line above and a subtitle of "The blackouts
that swept power systems out West last year could have been prevented by a
centralized automatic response system."  The lead figure is a map of the
Western states showing in sequence the locations of 48 distinct events that
occurred during the cascading outage of 10 Aug 1996.  (For background, see
the discussion in RISKS, beginning in RISKS-18.32.)  The title and subtitle
give a clear indication of what the authors have in mind -- protecting the
power system as a whole, not just protecting the individual transmission
lines from overloads.


"My Hairiest Bug War Stories" (*CACM*)

"Peter G. Neumann" <neumann@chiron.csl.sri.com>
Wed, 16 Apr 97 17:26:31 PDT
The April 1997 *Communications of the ACM* (pp. 30-37) has a risks-relevant
article by Marc Eisenstadt (title = subject: above), presenting an analysis
of some debugging tales reported to him.  My favorite among those he cites
is this:

  I once had a program that worked properly only on Wednesdays...
  The documentation claimed the day of the week was returned in a
  doubleword, 8 bytes.  In fact, `Wednesday' is 9 characters long,
  and the system routine actually expected 12 bytes of space to put
  the day of the week.  Since I was supplying only 8 bytes, it was
  writing another 4 bytes on top of the storage area intended for
  another purpose.  As it turned out, that space was where a `y' was
  supposed to be stored for comparison with the user's answer.  Six
  days a week the system would wipe out the `y' with blanks, but on
  Wednesdays, a `y' would be stored in its correct place.


The risks of not using your own security measures

<[name withheld by request]>
Wed, 16 Apr 1997
The military is filled with people who are constantly trying to justify
their existence and, worse yet, think that what they do is the most
important concern of everyone else.  The computer people are no exception.

Recently, there has been an enormous push for computer security.  The
computer people have gone crazy promoting COMPUSEC (computer security)
including safeguarding passwords.  As a matter of fact, they have made
everybody who touches a computer take an eight block test with 15 questions
each on computer security (complete with boring tutorials, fortunately
non-mandatory).  Since they didn't want to install the test everywhere, the
software was placed on central computers.

Well, the systems people finally got around to getting my work area attached
to the installation LAN.  Being the curious type, I nosed around some to
find out what resources were available.  On my second day of exploring, I
found a computer with some files that weren't password protected.  One of
the files was a database file that I decided to look at.  Lo and behold, to
my amazement I found dozens of unencrypted passwords.  I knew that the
program wasn't critical, but I also realized that people reuse passwords.

Being the security conscious kind-of-guy that I am, I called the systems
office to let them know about this breach of COMPUSEC.  I described what I
found and tracked down the computer on the LAN to aid the systems office.
Wouldn't you know it?  I happened upon one of the central computers for the
COMPUSEC tests and found the password file for it.

Later that day there was an e-mail to all of the users (using a different
e-mail system) advising them to change passwords if they used that machine.

Systems people: please make sure you follow your own rules.  You can be sure
that other people aren't.


Daylight savings change problem

Steve Doig <steve.doig@asu.edu>
Tue, 15 Apr 1997 15:37:04 -0700
This was sent to me by a friend who works at a newspaper that I'll leave
unnamed:

A funny thing happened this weekend.  The **ONLINE EDITION** copy is
generated by an automated conversion from typesetter copy to online copy
that works for the **PAPER**.

The program runs on a schedule, every morning at 2:15 a.m.  But, of course,
there was *no* 2:15 a.m. this Sunday!! The NT servers dutifully jumped from
2 a.m. to 3 a.m. without missing a beat.

But there was no copy on **ONLINE EDITION** come Sunday morning. Oops. They
had to move as much of it by hand as they could.

I'm sure this RISK has been well-discussed in RISKS, but I can't wait to
see what happens this fall.

Stephen K. Doig, Professor, Cronkite School of Journalism, Box 871305,
Arizona State Univ., Tempe, AZ 85287-1305 1-602-965-0798 steve.doig@asu.edu

  [I presume you might get TWO copies!  PGN]


Using GPS as your time standard (re: Horner, RISKS-18.96)

"Bernard Lyons" <bernard_lyons@qm.claris.com>
16 Apr 1997 15:08:17 -0700
Many readers might be tempted by the availability and reliability of GPS to
buy an inexpensive receiver and use it as a highly accurate time source for
computer systems.  I would caution against relying blindly on GPS to set
your clock by.  In addition to 1999's 13-bit overflow problem, GPS is
currently 11 seconds ahead of UTC.
  http://tycho.usno.navy.mil/leap.html
If one system takes its time from GPS, and another from UTC (like most
telecommunications networks do?), then there could be trouble.  In some
applications, 11 seconds is an eternity.

Bernie


Re: Fake "PGP CRACKED" message lures users into trap (Ziglar, R-19.08)

Fred Cohen <fc@ca.sandia.gov>
Thu, 17 Apr 1997 08:45:31 -0800 (PST)
The claim was apparently in a forged e-mail asserted to be from me
(fc@all.net)!  I would like to take this opportunity to formally deny that I
ever made a 5-line program that cracks PGP available via FTP or Telnet on
the all.net server.

Fred Cohen can be reached at tel:510-294-2087 fax:510-294-1225


Re: DES Challenge risks

Thomas Koenig <ig25@mvmap66.ciw.uni-karlsruhe.de>
Thu, 17 Apr 1997 19:36:19 +0200 (MET DST)
You may have heard of the effort to crack the DES challenge by
a group originating from Sweden (http://www.des.sollentuna.se/).

This has one very worrying aspect:  The organizers don't give out the
sources.  The reason given on their web site is:

>   Q5: Will you release the source-code? And why not!?
>   No, unfortunately we will not release the sourcecode for the client.
>   This is due to the fact that people may, advertently or inadvertently,
>   modify the client so that it breaks. This would of course jeopardize
>   the entire effort, since some clients would not be able to find the
>   correct key. When the project is finished, we will release all of the
>   source-code used in the project.

There are quite a lot of things a malicious binary expected to soak up
cycles of CPU could do:

a) The program could do any of the the traditional naughty things
   (send out password information, install Trojans or back doors, ...)

b) The program could look for local passwords, try to crack them,
   and send them back to the master server.

c) The program could also try to crack other codes.  The master
   DES keys of the EuroCheque ATM cards, for example, would be a
   an attractive target.  [There are about 40 million EC ATM cards in
   use in Germany today; fraud involving EC cards is increasing].

Point c) is especially worrying.  I do assume the organizers themselves are
honest (mostly because at least two people I know quite well by 'net
reputation are involved in this).  But even with that assumption, a criminal
could still break into the organizer's web site and substitute modified
clients.  The organizers have take no precautions against this that I can
see.  There are no PGP signatures of the supplied binaries, not even MD5
checksums (which a criminal could also alter on the web pages).

Finally, the organizers also rely on security through obscurity to
ensure integrity of their clients:

>   Both between a client and a server and between a server and the
>   masterserver, a special authentication method is used to make sure
>   that it is the correct program in the other end. This is done to avoid
>   people from disturbing the challenge by reporting in blocks as
>   finished even if they are not.

It's almost unnecessary to say that this is not good enough.

Thomas Koenig, Thomas.Koenig@ciw.uni-karlsruhe.de, ig25@dkauni2.bitnet.


Re: Social Security--the other side (Garfinkel, RISKS-19.05)

<Carey_Tyler_Schug@em.fcnbd.com>
Thu, 17 Apr 1997 07:52:57 -0600
Sometimes one's person's privacy is a risk to the rights of others, and
privacy should be sacrificed.

> "In this instance, people familiar with the new Social Security system
> say, there is danger for abuse from many directions: a legal adversary, an
> employer seeking to learn about an employee's outside income, an ex-spouse
> contemplating adjustments in support."

Those sound like usually legitimate uses:

1. Nearly all employers require an affirmation not to work for anybody who
might conceivably be a competitor.  If a person lied about it, this is the
first step to investigating such abuse.

2. An ex-spouse with a support payment of a percentage of income is
[otherwise] at the mercy of the person reporting income.

Of course, I am an extremist, and I believe that if we want to claim our
government is a democracy, then *ALL* government information should be
public.  Period.

That includes all tax forms for all taxing bodies and all taxed individuals,
groups and businesses.  Only military and court documents could be sealed,
and then only for a minimum amount of time.  The absolute maximum for court
documents, for instance, should be the lifetime of the litigants and
occasionally of a witnesses (If a witness admitted to having an affair with
one of the litigants, and it was a significant portion of the case, the
records could be sealed till the witness' death).

Just a side note: If tax returns were made public, that might spur the
greatest tax simplification in history, to the point where almost everybody
could do their Federal Income taxes in an hour or two.


Re: YAAXF: Yet Another ActiveX Flaw (Kennedy, RISKS-19.06)

Russ <Russ.Cooper@RC.on.ca>
Thu, 10 Apr 1997 19:29:30 -0400
Oh please, when will the media, and RISKS, stop pampering to the misinformed
just because it seems to make a story?

ActiveX objects don't attempt to prevent any action, beyond the security
pre-existing on the running OS.  Authenticode is for identification and
integrity, not prevention of malicious apps doing malicious things.  Who's
said otherwise?

Sun says "security loophole" and the media jumps up and down with glee.
Fact is there is no "security loophole" since there was never an attempt to
prevent the applications functionality in the beginning.

Sun says "specially written program containing ActiveX", what they really
mean is simply an ActiveX object.  What's specially written?

Sun says "the program then took over the user's computer", why'd they bother
to do that?  Besides, its highly unlikely that the ActiveX object actually
prevented the user from doing other things.

Sun says "personal financial information", how'd they distinguish between
personal and business financial information?

> > McNealy ... said they see security as a major issue differentiating Java...

Oh, so like all the looming issues regarding Java have now disappeared
forever?

Finally, why we needed to hear from David Kennedy that the ActiveX object
was signed is beyond me, and beyond what I thought was the scope of
Risks. Who cares if it was signed, was it signed by some reputable business
attempting to be legitimate or was it signed by Sun for Sun's internal
consumption (or maybe to be included in an up-coming release to their most
favoured developer?). The signature is irrelevant, its merely intended to
guarantee who wrote the object and that the object is delivered as it was
written. It has absolutely no bearing on the content of the object (beyond
telling you who wrote the hack), and certainly no bearing on Risks, IMO.

Stick to Risks.  Accepting ActiveX objects across untrusted boundaries
without prior understanding of the importance of the digital certificate is
a risk, period.

Russ  R.C. Consulting, Inc. - NT/Internet Security
owner of the NTBugTraq mailing list: http://ntbugtraq.rc.on.ca/index.html


They fixed one! 11-digit dialing in San Diego

Mark Seecof <Mark.Seecof@latimes.com>
Wed, 16 Apr 1997 12:13:59 -0700
Without fanfare, Pacific Bell has modified the switch software in downtown
San Diego to allow 11-digit dialing even of local (7-digit) numbers.  By
making it simpler to program (especially mobile) computers (or people) to
make calls reliably, this reduces some of the risks which RISKS contributors
have lamented over the years.


Risks of Mail Merge for Ontario NDP

Mark Connolly <mark@connollydesign.com>
Thu, 17 Apr 1997 14:56:11 -0400
Regarding the use of a database of street names to spew out thousands of
amendments to a proposed government bill in the Legislature of Ontario,
technology is a sword that cuts both ways.

It turns out that, as with many a similar database, the one used by the New
Democratic Party (NDP) had duplicate or similarly named items in it (Old
Orchard Grove and Old Orchard Grv., for example). The NDP found itself
needing to occasionally interrupt the proceedings on points of order to
withdraw from consideration those errant amendments.

The proceedings were carried on the Legislature's cable TV channel, and I
watched the shenanigans at various and found the whole display hugely
entertaining (but then, I once participated in a performance of Erik Satie's
"Vexations").

I happened to catch this little nugget one night, from Gilles Bisson
(Member for Cochrane South):

  Point of order, Chair: You'll note that the following amendment has the
  following: Richmond Street and Richmond Court -- r-i-c-h-m-o-n-d street
  and Richome, spelled differently, r-i-c-h-o-m-e, Court. It looks like the
  IBM PC broke down just like normal and the PC printed two of them at the
  same time. So if we used the Mac maybe this wouldn't have happened. It's a
  PC problem. I'd like to withdraw that amendment.

Hansard has transcripts of the whole thing up on the Web, another example of
my tax dollars hard at work. The above snippet can be found at:
<http://www.ontla.on.ca/hansard/36_parl/session1/house/0497/L176_18.htm>

I'd guess that Mr. Bisson was enjoying the fact that the "PC problem" he
referred to could be taken to mean a problem with a personal computer or a
problem with the governing Progressive Conservative party.

Mark Connolly Connolly Design Inc., Waterloo, Ontario, Canada
http://www.connollydesign.com


Daylight Time and UTC

Maggie Iaquinto <iaquinto@ozemail.com.au>
Thu, 17 Apr 1997 07:14:49 +1000 (EST)
As a ham-radio operator, I use satellite tracking programs. One of the best
of these programs requires the user to enter the timezone offset. Here in
Melbourne, Australia, the offset is +10 hours. Then it asks to set the
Daylight Flag if it is now Eastern Summer Time. When I do, the tracking
program shows the time in UTC with Local Time as +11 hours. When we switch
back to Standard Time [Spring ahead, Fall behind], I remove the Daylight
Flag.

Why is such an implementation so difficult, Microsoft?

Maggie  iaquinto@ozemail.com.au


Re: More on GMT vs BST: RS6000 (RISKS-19.08)

<andrew_yeomans@uk.ibm.com>
Wed, 16 Apr 1997 05:06:53 EDT
The AIX time rules can be changed using the TZ environment variable. It is
documented under "environment File" (/etc/environment) in Files Reference
book.  I'm currently using "TZ=GMT0BST,M3.5.0,M10.4.0" which works for most
years, depending on our legislators.

Andrew Yeomans, Andrew_Yeomans@uk.ibm.com  NOSS/VNET: WINVMD(YEOMANA)

  [Also noted by "Eric Ball" <ericball@VNET.IBM.COM>.  PGN]


Re: GMT, BST, UTC and all (Minow, RISKS-19.08)

Ian Miller <firewalls@scientia.com>
Wed, 16 Apr 1997 12:00:19 +0100
>It should be pointed out that the United States Naval Observatory
><http://tycho.usno.navy.mil/> distinguishes between UTC and GMT (which is
>currently one hour ahead of UTC).

No.  It quotes "GMT/BST" as currently BST and one hour ahead of UTC.  It
also confusingly uses GMT as an abbreviation for "Greenwich Mean
Time/British Summer Time".

The authority defining GMT is the Royal Greenwich Observatory
<http://www.ast.cam.ac.uk/RGO/>.
In <http://www.ast.cam.ac.uk/pubinfo/leaflets/time/time.html> they state:

RGO>In the UK we use Greenwich Mean Time (GMT) which in fact nowadays is
RGO>Universal Time (UTC). In the summer we adjust our clocks to British
RGO>Summer Time, BST, which is one hour in advance of GMT.

> It would seem, then, that Windows 95 is correctly advancing GMT when the
> user selects "adjust for daylight savings changes."

No. GMT is always UTC. The current UK time is BST = GMT+1.   [...]


Re: GMT, BST, UTC and all

"Bernard Lyons" <bernard_lyons@qm.claris.com>
16 Apr 1997 13:32:03 -0700
GMT (Greenwich Mean Time) is the standard time at the Meridian at Greenwich
Observatory in London, at zero degrees longitude.  It was originally derived
from the sun's noon position at Greenwich.  For many years it was the "base"
standard for the world's timekeeping, local timezones being promulgated at
some offset from GMT.  UTC (Coordinated Universal Time) is a newer time
standard, sanctioned by international standards bodies and kept by scores
(hundreds?) of advanced "clocks" around the world.  There's also
International Atomic Time (TAI) which currently differs from UTC by 30
seconds.  UTC differs from GMT by some small number of seconds.  These time
standards vary a little because of occasional corrections (such as the
addition of leap seconds) to account for tiny changes in the Earth's
rotation speed.  A fuller explanation can be found at:
  http://www.ast.cam.ac.uk/pubinfo/leaflets/time/time.html

For all practical purposes, however, UTC and GMT are the same - and always
stay the same. GMT does not change: it neither "springs" forward nor "falls"
back.  GMT is used as standard (winter) time for Britain and Ireland, but
for historical & cultural reasons it is still called GMT and not British
<something> Time.  I suspect that this is what may cause confusion in the
minds of US citizens, programmers included.

At 01:00 GMT on the last Sunday in March each year Britain and Ireland
advance clocks by one hour.  This is British Summer Time (BST), or GMT+1.
Clocks are put back an hour at 02:00 (local time, still 01:00GMT) on the
last Sunday in October each year.  GMT itself stays put.

This system of advancing clocks by one hour from spring to autumn was used
in Britain from 1916 up to the Second World War.  During WWII Britain was
run on GMT+1 during the winter and GMT+2 during the summer, partly to allow
munitions factories a longer production day.  Britain reverted to GMT/GMT+1
in 1948.  The changeover dates were adjusted in recent years to harmonise
with the rest of Europe.
  http://www.ast.cam.ac.uk/pubinfo/leaflets/summer/summer.html

Interestingly, the UK's Royal Society for the Prevention of Accidents
(RoSPA) believes that many lives could be saved in the UK each year if
Summer Time was adopted permanently.  Using GMT+1 all year round was tried
in a 3-year experiment from 1968 to 1970.  This was called British Standard
Time [unfortunately, also BST!  PGN].  RosPA predict more road accidents in
the dark mornings, but fewer in the brighter evenings as tired drivers make
their way home.  They estimate the net benefit for the UK's 50 million or so
population at up to 400 fewer fatalities and about 10,000 fewer serious
injuries.  Political considerations within the UK have prevented this idea
from being implemented so far.  The Labour party (expected to win the
forthcoming election) have said that they will adopt GMT+1, at least
experimentally.

The idea is that shifting the clock forward for the summer "saves" energy by
moving the work day closer to the actual hours of daylight.  In our modern,
high-speed, global, 24-hour society this concept is perhaps of less benefit
than it was. Especially with abundant artificial light and too-cheap
energy... but that's an argument for another time and place ;-).  However,
there are now many more time-dependent systems to change twice a year than
there were in the 1940's and perhaps the costs are beginning to outweigh the
advantages.

The RISKS of something new or unexpected going wrong with
computer-controlled systems because clocks are out of sync seems to me to be
increasing with the number and interconnection of such systems, and our
increasing dependence on them.  Perhaps it's time to seriously consider
dropping Daylight "Savings" Time (originally an American idea!)  altogether.

Bernard Lyons  (bernard_lyons@claris.com)  Dublin, Ireland.


Re: GMT, BST, UTC and all

Ian Stephens <Ian.Stephens@b-g-trading.btx400.co.uk>
Thu, 17 Apr 1997 11:15:50 +0100
  [... stuff duplicating Bernard Lyons' note omitted.  PGN]

BST is sometimes used (totally incorrectly) by the uninformed to mean "GMT
or Summer time, as the case may be, depending on the season".  There are
examples of this on various web pages, some I am ashamed to admit
originating in the UK.

I note that during WW2 in the UK Double Summer Time (GMT+2hr) was kept - if
carried on today (as has been suggested), this would give scope for
confusion with DST=Daylight Saving Time?

Useful basic info giving an idea of the complications of time zones in
Europe is shown at:
  http:/wsspinfo.cern.ch/file/sunos-europe

It is clear that it is impossible to program in future summer time changes
more that a year ahead, given the reliance on government decision rather
than precise formulae.  Very RISKy to rely on your OS getting it right for
you.

Ian Stephens <Ian.Stephens@b-g-trading.btx400.co.uk>

  [And there will still be screwups...  PGN]


"Network Security" by Kaufman/Perlman/Speciner

Rob Slade <roberts@mukluk.hq.decus.ca>
Wed, 16 Apr 1997 11:03:12 EST
"Network Security", Charlie Kaufman/Radia Perlman/Mike Speciner, 1995
%A  Charlie Kaufman charlie_kaufman@iris.com
%A  Radia Perlman perlman@novell.com
%A  Mike Speciner ms@color-age.com
%C  One Lake St., Upper Saddle River, NJ   07458
%D  1995
%G  0-13-061466-1
%I  Prentice Hall
%O  +1-201-236-7139 fax: +1-201-236-7131 beth_hespe@prenhall.com
%P  505
%T  "Network Security: Private Communication in a Public World"

For communications security, this is the text.  A solid conceptual
background covers cryptography and authentication.  The number theory basis
of much of modern encryption is provided as well.  In addition, there is
overview coverage of specific security implementations, including Kerberos,
PEM (Privacy Enhanced Mail), PGP (Pretty Good Privacy), and a variety of
proprietary systems.  Where many security texts use only UNIX examples, this
one gives tips on Lotus Notes, NetWare, and Windows NT.

The explanations are thorough and well written.  The organization of the
book may be a bit odd at times (the explanation of number theory comes only
after the discussion of encryption that it supports), but generally makes
sense.  The end of chapter "homework" problems are well thought out, and
much better than the usual reading completion test.

copyright Robert M. Slade, 1996  BKNTWSEC.RVW  961209
roberts@decus.ca  rslade@vcn.bc.ca  rslade@vanisl.decus.ca

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