September 2023 - pacsat-dev - mailman.amsat.org

Re: monitor command
by Chris Thompson 15 Sep '23

15 Sep '23

There was no change to the monitor command that I remember. It does print the RSSI when it is over a certain "squelch" threshold. If it is printing it continually then it may be getting RFI on the 2m receiver. 73 Chris On Fri, Sept 15, 2023, 11:34 Bill Reed via pacsat-dev <pacsat-dev(a)amsat.org> wrote: > When is set monitor on on version "i" I get random rssi readings? Is > this expected? > > > > ----------------------------------------------------------- > > pacsat-dev mailing list -- pacsat-dev(a)amsat.org > View archives of this mailing list at > https://mailman.amsat.org/hyperkitty/list/[email protected] > 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 >

1 0

monitor command
by Bill Reed 15 Sep '23

15 Sep '23

When is set monitor on on version "i" I get random rssi readings? Is this expected?

1 0

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/[email protected] > 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

1 0

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

1 0

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

1 0

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/[email protected] 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

1 0

CPushed Updates to PCB and Schematic
by Bob Stricklin 15 Sep '23

15 Sep '23

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

1 0

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

1 0

CPU Pin Assignments
by Bob Stricklin 14 Sep '23

14 Sep '23

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

1 0

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

1 0