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Re: Using SHA256 for authentication
by Chris Thompson 15 Sep '23

15 Sep '23

Ok, thanks for that Corey. Very interesting. We may not be susceptible to the length extension attack vulnerability though. If I understand correctly, then a message sent as: Hash( key + "Watch the enemy") could be manipulated to Hash(key + "Watch the enemy and attack them after 5 mins"), without knowing the key. But our commands are fixed at 18 bytes length (for now at least). So any extra appended message would be ignored. With that said, it may not be much harder to implement the scheme as described. Burms, just FYI. We discussed the authentication approach a bit last night and the fact that I could get the SHA hash function to work but could not get the AES encryption to work (in the ground station). Probably because I don't understand the exact flavor of AES that has been used.. Corey has seen another scheme in other projects that does not use encryption. It appends the key to the message and then calculates the hash. The message and hash are then sent without the key. The satellite then appends its own copy of the key to the message and calculates the hash to make sure it is an authentic message. The possible advantages of that scheme are that there is less calculation on the satellite (no AES) and it may not need the carve out to allow encryption of part of the Amateur Radio message - given that no encryption is used. It might then allow the satellite to be used in other settings, such as by a local club, without needing the carve out for encryption. Of course perhaps the regulators would still see the SHA hash function as "encrypted". I don't know. 73 Chris On Fri, Sep 15, 2023 at 10:06 AM Corey Minyard via pacsat-dev < pacsat-dev(a)amsat.org> wrote: > I was going through my head trying to remember stuff about this, and I > realized that just combining the key and message has some weaknesses. > That nagging feeling in the back of your brain. Here's the more > secure way to do it: > > https://en.wikipedia.org/wiki/HMAC > > -corey - AE5KM > > ----------------------------------------------------------- > > pacsat-dev mailing list -- pacsat-dev(a)amsat.org > View archives of this mailing list at > https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org > To unsubscribe send an email to pacsat-dev-leave(a)amsat.org > Manage all of your AMSAT-NA mailing list preferences at > https://mailman.amsat.org > -- Chris E. Thompson chrisethompson(a)gmail.com g0kla(a)arrl.net

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Using SHA256 for authentication
by Corey Minyard 15 Sep '23

15 Sep '23

I was going through my head trying to remember stuff about this, and I realized that just combining the key and message has some weaknesses. That nagging feeling in the back of your brain. Here's the more secure way to do it: https://en.wikipedia.org/wiki/HMAC -corey - AE5KM

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Thanks
by Jim McCullers 15 Sep '23

15 Sep '23

Thanks to the group for answering my question last night concerning Ubuntu and USB devices. I added my user name to Dialout using adduser and the USB ports became available. I appreciate the help. Now on to the next snag. Jim McCullers WA4CWI

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Re: CPushed Updates to PCB and Schematic
by Jim McCullers 15 Sep '23

15 Sep '23

Thanks. By the way, I forgot to mention I have the formulas used to calculate the Class E tank circuit for the AX5043 transmitter but have yet to cross check them with the three frequency settings given in the datasheet. Once I've done that, I'll calculate the component values for 435mhz which should cover any frequency range we might use for the downlink. Jim All, I did push the updates to the PCB and the schematic. Bob ----------------------------------------------------------- pacsat-dev mailing list -- pacsat-dev(a)amsat.org View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org To unsubscribe send an email to pacsat-dev-leave(a)amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org

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CPushed Updates to PCB and Schematic
by Bob Stricklin 14 Sep '23

14 Sep '23

All, I did push the updates to the PCB and the schematic. Bob

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Pacsat dev mtg 9/14/2023
by Bill 14 Sep '23

14 Sep '23

Pacsat dev mtg 9/14/2023 Thu, Sep 14, 2023 7:00 PM - 9:00 PM (CDT) Please join my meeting from your computer, tablet or smartphone. https://meet.goto.com/529052701 You can also dial in using your phone. (For supported devices, tap a one-touch number below to join instantly.) United States: +1 (872) 240-3311 - One-touch: tel:+18722403311,,529052701# Access Code: 529-052-701 Join from a video-conferencing room or system. Dial in or type: 67.217.95.2 or inroomlink.goto.com Meeting ID: 529 052 701 Or dial directly: 529052701(a)67.217.95.2 or 67.217.95.2##529052701 Get the app now and be ready when your first meeting starts: https://meet.goto.com/install

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CPU Pin Assignments
by Bob Stricklin 13 Sep '23

13 Sep '23

Attached is a list of the COU pin assignments for reference. Bob

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Release of PACSAT v0.1i and Pacsat Ground 0.45c
by Chris Thompson 13 Sep '23

13 Sep '23

I merged my latest branch into main and changed the version to 0.1i. This includes the ability to send (un-authenticated) commands. PacsatGround has also been updated to send the commands. Download here: https://www.g0kla.com/pacsat/index.php This also includes some updates to telemetry to fix some conversions and to include File System telemetry. These are all needed for the demo. 73 Chris -- Chris E. Thompson chrisethompson(a)gmail.com g0kla(a)arrl.net

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Schematic - PCB - BOM
by Bob Stricklin 09 Sep '23

09 Sep '23

All, I pushed an updated version up to GitHub today. Spent the better part of the day working the parts list. Have identified mfg part numbers for all parts now. Put that list into Mouser and found a couple of issues I am still working on. Two parts are not in stock or have minimum buys. I will fix these tomorrow then post the parts list here. Looks like we need about $350 per board in parts not counting the TMS570 and the AX5043. These last two are not on the list because they are not available at Mouser and we already have inventory on these at AMSAT I hope. I made the heat sink pad on the AX5043 smaller to be sure it would not be an issue. I added some circuitry to take care of powering down for the Transmitter when things go bad. Actually added a second watchdog chip for this. I figure we need the processor running on its own so we could upload code and commands if the transmitter is stuck in an effort to recover. I did a few other smaller task like renamed parts on the PCB and made minor changes in schematic. Will post updated PDF of these tomorrow. Bob

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Pacsat dev mtg 9/7/2023
by Bill 07 Sep '23

07 Sep '23

Pacsat dev mtg 9/7/2023 Thu, Sep 7, 2023 7:00 PM - 9:00 PM (CDT) Please join my meeting from your computer, tablet or smartphone. https://meet.goto.com/543292285 You can also dial in using your phone. (For supported devices, tap a one-touch number below to join instantly.) United States: +1 (571) 317-3122 - One-touch: tel:+15713173122,,543292285# Access Code: 543-292-285 Join from a video-conferencing room or system. Dial in or type: 67.217.95.2 or inroomlink.goto.com Meeting ID: 543 292 285 Or dial directly: 543292285(a)67.217.95.2 or 67.217.95.2##543292285 Get the app now and be ready when your first meeting starts: https://meet.goto.com/install

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