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ZL3AI > APRDIG 30.10.03 15:02l 259 Lines 9658 Bytes #999 (0) @ WW
BID : 2238-ZL3AI
Read: GUEST
Subj: TAPR Digest, Oct 28, 3/4
Path: DB0FHN<DB0RGB<OK0PPL<DB0RES<ON0AR<ZL2TZE<ZL3VML
Sent: 031030/1243Z @:ZL3VML.#80.NZL.OC #:11608 [Chch-NZ] FBB7.00i $:2238-ZL3AI
From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: Re: Idea needs feedback
From: James Washer <washer@trlp.com>
Date: Tue, 28 Oct 2003 09:56:46 -0800
X-Message-Number: 18
I'd love to see you publish this in something other than a '.doc' file...
Can't you save it as html from word?
- jim
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Subject: Re: Idea needs feedback
From: "Bud Talbot" <kb9wvg@arrl.net>
Date: Tue, 28 Oct 2003 12:15:55
X-Message-Number: 19
As plain .txt:
http://home.houston.rr.com/kb9wvg/APRS_Geo.txt
73 de Bud KB9WVG
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Subject: FIRENET Question
From: "David Thege" <dthege@conpoint.com>
Date: Tue, 28 Oct 2003 12:26:29 -0600
X-Message-Number: 20
I was looking at the fires in California being tracked on APRS and was
wondering what was what. I see fire symbols that say so much % and icons
that say no symbol yet. Also icons that say water station which I assume are
fill up spots for the Tankers. Can somebody explain what I'm looking at?
Dave N0XBN
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Subject: Re: Object security in APRS
From: "Tyler Allison" <tyler@allisonhouse.com>
Date: Tue, 28 Oct 2003 14:33:59 -0400 (GMT+4)
X-Message-Number: 21
>Any suggestions on how this should be done?
[note: I do security/encryption for a living if that maters]
Off the top of my head one could utilize a central Internet database
similar to a PGP keyserver where the callsign owner submits his public key
and can then 'sign' an APRS message with his private key. (Think log book
of the world or the EchoLink authorization system) Then anyone who wants
to check the authenticity of the message can check the signature of the
message against the available public key by doing a lookup on the authors
callsign.
Systems without 24/7 Internet connectivity would need some method of
'downloading' the keys they are interested and storing them in memory. The
ability to permanently store a handful should be enough if another option
I outline below is available. Then 'updating' the list whenever an
Internet connection was available.
For example..as a portable owner you want to verify all KI4BUM and
KD4KLY's messages because the three of you are working a special event.
You download those two keys to your tracker and store in 'permanent'
memory. Thus you dont need to download the entire Internet database of
keys, assuming you know ahead of time the folks you need.
Another option might be a trusted IGATE service. You download only the
IGATEs public key to your portable's 'permanent' memory. You then send a
query to the IGATE asking for KD4KLY's public key because you just saw a
message from him you want to check. The igate grabs it off the internet
and signs KD4KLY's key with it's own. You can then verify that KD4KLY's
key is correct by checking the IGATE's signature on the key. The portable
system can then store KD4KLY's key in it's non-permanent memory. One could
use an algorithm that stores the 20 most used keys (or whatever memory can
permit) and the rest get over written and queried for again if needed
later.
The terms you are interested in in the encryption space, should you wish
to do more research, are:
Authentication = Is the message from the person it say it is from
Integrity = Was the message modified by someone else
Nonrepudiation = The sender cant deny that he sent it
The above three are most often seen as:
Nonrepudiation = Add a 'trusted' timestamp to the message
Integrity = Add a hash of the message+timestamp to the message
Authentication = Digital Signature of the hash+message+timestamp
Authentication need not be used for all messages. If you simply want to
make sure you got the entire message you can use Integrity only.
I doubt there is much need for nonrepudiation in APRS.
Doing a simple hash of the message shouldnt add more than a handful of
characters to each message.
Signing the message could get more lengthy. Even the smallest of
public/private key algorithms could increase the size of a simple APRS
message from 25 characters to hundreds.
-Tyler
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Subject: Re: Object security in APRS
From: "Scott Miller" <scott@opentrac.org>
Date: Tue, 28 Oct 2003 10:52:48 -0800
X-Message-Number: 22
>Off the top of my head one could utilize a central Internet database
>similar to a PGP keyserver where the callsign owner submits his public key
I should have specified that it should be able to stand alone, without
access to a central registry. However...
>Authentication = Is the message from the person it say it is from
>Integrity = Was the message modified by someone else
>Nonrepudiation = The sender cant deny that he sent it
In this case authentication isn't our primary concern. So we can generate a
key pair for each object we want to create, and announce the key along with
the message. Doesn't tell you a damn thing about who's really sending it,
but you can verify that two messages have the same public key, and that they
were signed by the same private key.
>Doing a simple hash of the message shouldnt add more than a handful of
>characters to each message.
Yes, but how do you use the hash to verify that two messages came from the
same source? Either you've got to distribute a shared secret key, HMAC
style, in which case everyone can spoof the messages, or you use a
public/private pair to make sure only certain parties can generate messages
yet anyone can verify them.
>Signing the message could get more lengthy. Even the smallest of
>public/private key algorithms could increase the size of a simple APRS
>message from 25 characters to hundreds.
ECDSA has really good key efficiency. Perhaps we should be ignoring the
'DSA' part completely and just using it as a block cipher to encrypt a hash?
Do an MD5 hash on the message, and encrypt it so that anyone with the public
key can decode and verify it.
Still no good for tiny devices, but my plan is to use something like CRC32
plus the TEA block cypher algorithm for a secret key MAC... that should fit
in under 1K of ROM.
It's the public key stuff I'm not as familiar with...
Scott
N1VG
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Subject: Re: FIRENET Question
From: "Curt Mills, WE7U" <hacker@tc.fluke.com>
Date: Tue, 28 Oct 2003 10:53:03 -0800 (PST)
X-Message-Number: 23
On Tue, 28 Oct 2003, David Thege wrote:
>I was looking at the fires in California being tracked on APRS and was
>wondering what was what. I see fire symbols that say so much % and icons
>that say no symbol yet. Also icons that say water station which I assume are
>fill up spots for the Tankers. Can somebody explain what I'm looking at?
We'd be happy to!
On firenet, we have H2O objects, which are river gaging stations showing
water height at the gage in feet, water flow in cubic feet per second, or
both.
The regular fire symbols show percent contained. There are other MADIS
symbols which show hot spots that were determined via the MADIS satellites.
Your APRS client may not have updated symbols for those.
There are lots of weather stations as well, some of them ham, but many of
them are RAWS weather stations, CMAN weather stations, and others.
I think we're over 10,000 objects these days being posted to firenet.
See "http://www.dwrracesupport.com/fire/" for more info.
--
Curt Mills, WE7U hacker_NO_SPAM_@tc.fluke.com
Senior Methods Engineer/SysAdmin
"Lotto: A tax on people who are bad at math!"
"Windows: Microsoft's tax on computer illiterates!" -- WE7U
"The world DOES revolve around me: I picked the coordinate system!"
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Subject: Re: Idea needs feedback
From: "Bud Talbot" <kb9wvg@arrl.net>
Date: Tue, 28 Oct 2003 12:54:16
X-Message-Number: 24
And as a .pdf (Thanks Scott)
http://home.houston.rr.com/kb9wvg/APRS_Geo.pdf
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Subject: Re: FIRENET Question
From: "Spider" <spider@rivcom.net>
Date: Tue, 28 Oct 2003 12:02:04 -0700
X-Message-Number: 25
Dave!
What software and Version are you running? You should not see "no-symbol
yet".
You should be seeing mainly the MEO symbol which is the MODIS Earth
Observation symbol. These are a Satellite view of probable fires...in this
case fires and hotspots. The H2O symbols are gaging stations which can be
in a lake, stream, wash, ditch, etc. They measure gage height and flow.
You can go to http://www.dwrracesupport.com/fire and get more info, but the
web page is currently being updated so some info is missing.
Jim
WA6OFT
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Subject: KPC-3+ Digipeater Question
From: "Eric Christensen" <kf4otn@earthlink.net>
Date: Tue, 28 Oct 2003 14:04:20 -0500
X-Message-Number: 26
Okay, I know that I have asked this question before, but here I go again
throwing another curve ball...
I now have the KF4OTN-6 APRS station setup as a stand-alone Weather Station,
R,T,W,n-n digipeater, and, when activated, EOC station. Now, I know that I
won't use the EOC symbol unless I'm activated, but now how do I show that I
am a digipeater and weather station? Which should I use?
Also, when I was setting all my settings in the modem, I found one entry I
wasn't familiar with.
UIFLOOD WIDE,30,NOID
What is the 30? Is that the dupe suppression time?
Thanks,
Eric KF4OTN
Eric Christensen
Radio Station KF4OTN
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