Question about WEP and passwords

I found this page on Apple's support site. It explains how different
manufacturers of wireless products use different 'hashing' methods to
create hex passwords (for WEP) and suggests using characters of a
certain length. Here is the page:

http://docs.info.apple.com/article.html?artnum=108058

Basically, it suggests that if you create a password of exactly 13
characters (if using 128-bit WEP) or 5 characters (if 64-bit), then you
don't have to worry if you're entering an "alphanumeric" or "hex" key.
(For wireless products, when you're entering a WEP password, most
products ask you if you're entering an alphanumeric key or a hex key.
This page suggests that, if you use a password of the length that it
suggests, you could enter the same password as alphanumeric or hex.)

Am I getting close to the truth here?

 

If you entered a 13-digit password in a 3rd party router, you
can still use the 26-digit hex code (preceded by the $-sign)
when setting up your airport client.

 

No. Each character of an alphanumeric key corresponds to two digits of
a hex key. A 128-bit key requires 104 user-supplied key bits, which
corresponds to 26 hex digits or 13 alphanumeric characters.

The point of the article is that many manufacturers allow you to enter
an alphanumeric key shorter than the required length; e.g. if you're
using 128-bit WEP, you could enter a 10-character alphanumeric key. The
system will perform a hash to get an equivalent 13-character key. The
problem is that different manufacturers may use different hash
mechanisms; so if you enter that 10-character password on the computer
and the router, they may treat them differently and you won't get a
connection.

Some simple hash functions that might (but probably aren't) used would
be to fill out the password with a simple character sequence. E.g. one
manufacturer could treat "shortpass" as "shortpassXXXX", while another
might treat it as "shortpassABCD".

By entering all 13 characters, you'll avoid this type of
incompatibility, since all the devices will treat the password the same.

 

Now this is where things start to get really weird. Understand that,
even if what I'm about to say, does not make a ton of sense, this is
what I did, and it works this way:

I entered my password, a 26-digit code, *as an alphanumeric password*.
That's what I did on every wireless thing I have: my iMac, my cable
modem (Toshiba PCX5000), printer (HP DeskJet 5850), and my TiVo. They
all accepted the code and work with it. The computer doesn't ask
whether or not the code I'm entering is alphanumeric or hex, but the
TiVo, cable modem, and printer all do, and I told them all it was an
alphanumeric code - and that worked.

As for the AirPort, I entered that same code as both an alphanumeric
and a hex, and NEITHER of them worked.

 

Then I wonder why most of my stuff lets me enter a 26-digit
alphanumeric code...

 

That may very well be. I don't suppose there's any way to find out if
this is what they're doing? (I had assumed that if I entered a code
that was too long, it would be rejected)

 

How do I find out the equivalent hex version of an alphanumeric key?

 

If the alphanumeric key is 13 characters long, it's just the character
codes. I'm sure there are plenty of web sites that have ASCII character
charts that show all the character codes in decimal, octal, and hex.

 

If your string is larger than necessary, it will be "hashed" down to
a shorter length. Perhaps by truncating the end, maybe by truncating
the beginning, or maybe with something else.

-- David

 

If your string is larger than necessary, it will be "hashed" down to
a shorter length. Perhaps by truncating the end, maybe by truncating
the beginning, or maybe with something else.[/QUOTE]

I see. Well, I changed to a different alphanumeric password, which is
exactly 13 characters long, and this seems to work. Maybe I'll give
the Airport Express another chance...

 

In fact, such a chart is on his system. See /usr/share/misc/ascii .

 

This may be just off the wall, but do you actually have
encryption turned on? Many systems allow you to set the key even
if WEP is not enabled and using it.

- Jeff

 

Found it! Thanks very much.

Now if only I could actually get my hands on another Airport Express
itself, I'm set.

One other question: If I'm entering a hex password like this, must I
use the Airport Admin Utility (on the brand-new straight-outta-the-box
Express), or can I enter a hex password via the Setup Assistant?