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 10 Issue 14

Friday 29 June 1990

Contents

o RISKS WILL BE ON VACATION
RISKS Forum
o Hubble
Dimitri Mihalas via Mark Bartelt
o Re: "Unbreakable Math Code Finally Broken"
Richard A. Schumacher
o More on the Risks of searching the Lexis fulltext database
Peter D. Junger
o Re: info on carpal tunnel syndrome
Terry Kane
o Info on RISKS (comp.risks)

RISKS WILL BE ON VACATION

RISKS Forum <risks@csl.sri.com>
Fri, 29 Jun 1990 13:34:45 PDT
for the next three weeks.  There might be an issue or two, but don't bet on it.
Keep sending in the good stuff in any case.  Thanks.  The Management


Hubble

Mark Bartelt <sysmark@orca.cita.utoronto.ca>
Fri, 29 Jun 90 13:20:14 EDT
[This is a message from Dimitri Mihalas (dmihalas@altair.astro.uiuc.edu).
Mark Bartelt, Canadian Institute of Theoretical Astrophysics]

in case you have not heard: from a reliable inside source i found out that the
problem with ST is that the SOFTWARE driving the polisher was defective. the
corrections for spherical aberration were put in with the wrong sign.
consequently the mirror is not corrected for sph. abb., but has an added dose
of it.

the error was not detected during testing because no test with collimated
light was ever done. (editorial remark: unthinkable!) apparently this was
a $30M economy measure in the face of the Challenger accident. likewise
none of the optics were ever tested in vacuum. the primary was and is
"perfect" relative to the specified curve; but alas the specification
was wrong. sigh.

from my amateur astronomer days (does that include 1990?) i recall that
spherical aberration is EASY to detect with the foucault test, which is
done with a pinhole, not collimated light. it is hard to believe that
ANYONE could have made such a blunder..

the only reason that people know this much is that the same software
was used for AXAF. the errors there were so huge as to be immediately
noticeable, and when the software was corrected, the mirror was "perfect".
i don't know whether the information from axaf was available prior to
the launch of ST, but it seems that it had to be. in which case one
wonders why PE didn't issue a "hold everything!".

the future: no chance of bringing the whole telescope down for a refit.
best plan is to design compensating optics into the lightpath for future
instruments: relatively easy to do. but that will still take 3-5 years.

i suppose it's "win a few, lose a few..." but i personally think that
nasa, the government, and the people should stick it into PE and TURN
it hard until they agree to refund the cost of the mistake and of the repairs.
i'm sick of seeing defense and defense-related contractors get away
with bloody murder and just get fatter and fatter on the profits.

back to theory
dimitri


Re: "Unbreakable Math Code Finally Broken"

Richard A. Schumacher <schumach@convex.UUCP>
28 Jun 90 18:02:18 GMT
Y. Radai <ADAI1@HBUNOS.BITNET> writes:
>  So the statements that an impenetrable code has been broken and that
>organizations need to change their cryptographic systems because of this
>achievement seem a wee bit exaggerated.

On the other hand, the NPR report mentioned that the Bank of England
was planning to use a 150 digit number as a key in a new transaction
processing system, but changed it to something "much larger" when
they learned of the 9th Fermat prime factoring.


More on the Risks of searching the Lexis fulltext database

<junger@cwru.cwru.edu>
29 Jun 90 16:25:00 EST
        A while back I sent to RISKS an (itself rather buggy) description of a
bug that turned up in the Lexis/Nexis database when I was doing date delimited
searches in the library containing the fulltext opinions of the United States
Supreme Court.  A representative of Mead Data Central--the owner of the
Nexis/Lexis service--has since contacted me to explain the nature of the bug
and to assure me that it will be corrected on June 30.

        In the first place, it appears that the bug is _not_ in the
basic software that searches through the database for cases decided on,
after, or before a specified date.  Secondly, it is clear that the bug
did _not_ cause me to miss any cases that I should have located, it just
turned up some additonal cases that were not decided within the period
that I was searching.  That is the good news.

        The bad news is that the problem relates to the way that the
Lexis/Nexis system parses dates in the database and that the proposed
fix will work only until the year 2000, at which time a new variant of
the bug should cause real havoc.

        Here is a corrected version of the type of search that exposed
the bug:

        Entitlement and date(aft 12/31/39 and bef 1/1/50)

That search, when conducted in the Supreme Court file, should find all
opinions, and only those opinions, decided by the United States Supreme
Court during the decade of the 1940's that contained the word
`entitlement'.  (Lexis warned me that it assumed that I meant after
12/31/1939 and before 1/1/1950.)  As it happens, there are no cases that meet
those criteria.  But Lexis reported that it had found a dozen or so
cases--cases that did contain the word `entitlement' but that were
decided in the 1960's, 70's, and 80's.

        It seems that a couple of months ago Mead Data Central decided
to include the argued-date as well as the decided-date within the date
field, and it is this enhancement that caused the bug.  The fix that
will be implimented this Saturday is to once again exclude the
argued-date from the date field.

        Since cases are not always decided in the same year that they
are argued, including the argued-date in the date field will, of course,
cause some cases to be reported as occurring in two different decades,
which would be a nuisance.  But that is only a miniscule part of the
bug.  The real problem occurs because some cases are argued on more than
one date, so that the argued-date field would appear in the database as,
say:  "argued June 22-23, 1980" and the decided date field as: "July 3,
1980)."  At first glance that would not seem to cause any problem.  And
it wouldn't, except for the fact that the Lexis system parses the date
fields in the same way that it parses user input, and thus concludes
that "June 22-23" means "June 22-1923".  Thus our hypothetical case
would have a date of July 3, 1980 (which is after December 31, 1939) and
would also have a date of June 22, 1923 (which is before January 1,
1950).  If that case--decided, you will recall, in 1980--contains the
word `entitlement' it will turn up in my search for cases in the decade
of the 1940's, and in my searches in the 1950's, and in the 1960's, etc.

        I can understand why the system parses user input so as to
interpret 1/1/50 as 1/1/1950--but I never dreamed that a system would
parse its own data.  According to the people at Mead Data Central,
however, their system parses the data fields in exactly the same way
that it parses user input.  It seems that the Lexis/Nexis database
contains texts--especially news reports--with dates in the form
"nn/nn/nn". Today those dates are parsed as "nn/nn/19nn", but what is
going to happen in the year 2000?

        It would seem that ambiguous data in the data base will be much
harder to find and fix than a software bug.

Peter D. Junger, CWRU Law School


Re: info on carpal tunnel syndrome (CTS)

Terry Kane <tok@stiatl.UUCP>
29 Jun 90 19:36:47 GMT
I am a long time sufferer of CTS.  The first symptoms I recall were during
high school, nearly twenty years ago, but it was not properly diagnosed
until I was in excruciating pain, dropping things, not sleeping because
my hand was burning at night and more, all about four years ago.

Tests said that I had "a very mild case"!?  That reassuring info did not
make my hand better.  I used splints, Motrin, ice until I finally insisted
on the carpal tunnel relief operation.  That was two years ago, this month,
but I still have recurrences - especially when I meet the same RISK which
pushed my CTS over the edge: using a MOUSE.

The typical mouse promotes all the bad habits that can result in CTS symptoms.
One typically rests the heel of the palm on the mouse, and press the chord
keys - frequently with constant pressure (on Apple's mice, the required
pressure is substantial for me, and their new mouse reqlly aggravates the
problem with its stylized, aerodynamic "look").  I cannot use a mouse to this
day without suffering a "mouse hangover".

Track balls are better for me, but I still would rather avoid them.

I am really looking forward to _getting_my_hands_on_ ;-) a touch screen.
I've seen some very nice ones with quite satisfactory resolution!

And please - If you think that you might have CTS - don't waste time.
            See Your M.D.

Terry Kane, Sales Technologies, Inc, Atlanta, GA  (404) 841-4000

Please report problems with the web pages to the maintainer

Top