SJS wrote:
begin quoting Ralph Shumaker as of Wed, Dec 05, 2007 at 08:06:47PM -0800:
A passing glance might be enuf to tell me which key blank to use. A
close look (about a foot away from my eyes) for about 5 to 10 seconds
would probably be enuf in most cases for me to be able to reproduce it.
Double the time if they are sitting at about arms length. Reducing the
time or increasing the distance will make it more difficult. If the key
of interest is sitting at a good angle while I'm standing nearby talking
to someone, I may be appearing to stare off into space while examining
the pattern. If I can read the 5 or 6 digits stamped on some keys, the
resulting key will almost certainly work.
So how many bits of information are actually encoded in n a typical
physical key?
Four to six tumblers, three values for each, plus a few hundred styles
of key blank?
A typical house or office key has 5 tumblers, either 6 or 10 values for
each, and two styles of key blanks, typically. And the two styles
usually have heads that give you a *very* good clue as to what it is.
A typical car key has 8 to 10 tumblers, about 4 to 5 values for each,
and a few hundred styles of key blank. Head patterns usually don't
reveal much about the key style (groove pattern, that which determines
if it will even slide into the hole).
I was speaking of house and office keys, altho with practice, I could
probably do almost as well with car keys (looking at them and copying
them that is).
Otherwise, it really depends
on my ability to estimate the pattern I'm seeing, as well as how well
the key I'm examining was cut in the first place. Also a factor is how
well worn the key is. If you have ever seen a well used older-GM
ignition key (where the doors take a different key), that is a good
example of a key so worn that it is difficult to reproduce, even with
careful study.
I used to drive a pontiac firebird. By the time I got rid of it, the
ignition key would fall out of the ignition.
Not uncommon for that key and ignition.
I figured that all it would take to start the car would be a thin enough
screwdriver.
only if the screwdriver had an edge pattern close enuf to align the
tumblers. But being a sidebar design, and being that old, you may have
been right.
--
Ralph
--------------------
The spelling of words is subordinate. Morbidness for nice spelling and tenacity
for or against one letter or so means dandyism and impotence in literature.
--Walt Whitman
--
[email protected]
http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
