[security] Introducing signing support to MySensors

[alexsh1]

@Anticimex Ok, but is there a reason why one would have HMAC key in both ATSHA204a and EEPROM?

[Anticimex]

@alexsh1 no, not really. If you have a atsha204a the only reason to not use it would be performance. Software signing executes slightly faster due to the single write protocol of the atsha.

[alexsh1]

@Anticimex Thanks very much for your help - I must admit it was a bit of a challenge to jump straight away from a stable 1.5.4 to 2.0 beta

[Anticimex]

@alexsh1 yes there have been a lot of changes but hopefully they are perceived as improvements. Feedback on signing usability is always welcome :)

[alexsh1]

@Anticimex BTW, is signing compatible between 1.5.4 and 2.0b?

[Anticimex]

@alexsh1 no, it is not

[alexsh1]

@Anticimex Right, this is why I am not able to sign 1.5.4 nodes with 2.0b GW.
In fact when I inserted #define MY_SIGNING_REQUEST_SIGNATURES into the GW code, some nodes stopped working and I think it has to be with signing as GW is throwing a lot of messages that signing failed.

Bottom line is that I need to upgrade pretty much all sensors :-(

[Anticimex]

@alexsh1 yes, Unfortunately. But it is a huge release upcoming. And a major version step, hence the incompatibilities. Hopefully, the changes made will make it easier to do future maintenance.

[cingolanifede]

Hi. Is there any difference in using RFM69? Signing is supported using that radio? Thanks

[Anticimex]

@cingolanifede signing has nothing to to with which radio you choose so yes. It supports any transport, but to my knowledge it has only been actually tested with nrf24 and rfm69.

[alexsh1]

@Anticimex I must admit that signing is working really-really nicely on my custom made nodes (Soft sign and ATSHA204A)

Apart from a small issue with the sensebender, which I believe is not a signing issue, it is working like a charm. All credit to you! Thank you

Starting sensor (RNNNAS, 2.0.0-beta)
Radio init successful.
HTU21D Sensor1.1 - Online!
isMetric: 1
TempDiff :1098.00
HumDiff  :136.75
T: 998.00
H: 36.75
send: 5-5-0-0 s=0,c=1,t=0,pt=7,l=5,sg=0,st=ok:998.0
send: 5-5-0-0 s=1,c=1,t=1,pt=7,l=5,sg=0,st=ok:36.7
send: 5-5-0-0 s=2,c=1,t=38,pt=7,l=5,sg=0,st=ok:3.29
send: 5-5-0-0 s=255,c=3,t=0,pt=1,l=1,sg=0,st=ok:106
Signing required
send: 5-5-0-0 s=255,c=3,t=15,pt=0,l=2,sg=0,st=ok:


Waiting for GW to send signing preferences...
Skipping security for command 3 type 15
read: 0-0-5 s=255,c=3,t=15,pt=0,l=2,sg=0:

Mark node 0 as one that do not require signed messages
Mark node 0 as one that do not require whitelisting
send: 5-5-0-0 s=255,c=0,t=17,pt=0,l=10,sg=0,st=ok:2.0.0-beta
send: 5-5-0-0 s=255,c=3,t=6,pt=1,l=1,sg=0,st=ok:0
Skipping security for command 3 type 16
read: 0-0-5 s=255,c=3,t=16,pt=0,l=0,sg=0:
Signing backend: ATSHA204Soft
SHA256: 2C4A871ACCAE26760F41E547DD39B7B816FE22EEBCD8DFA2FE00000000000000
Transmittng nonce
send: 5-5-0-0 s=255,c=3,t=17,pt=6,l=25,sg=0,st=ok:2C4A871ACCAE26760F41E547DD39B7B816FE22EEBCD8DFA2FE
Signature in message: 01C31110DAE29D5DCD3771F68B6F29B5CCCF43A3D5397CC8
Message to process: 00050E0306FF4D
Current nonce: 2C4A871ACCAE26760F41E547DD39B7B816FE22EEBCD8DFA2FEAAAAAAAAAAAAAA
HMAC: 0CC31110DAE29D5DCD3771F68B6F29B5CCCF43A3D5397CC89A82A89D87E931B8
Signature OK
read: 0-0-5 s=255,c=3,t=6,pt=0,l=1,sg=0:M
send: 5-5-0-0 s=255,c=3,t=11,pt=0,l=24,sg=0,st=ok:Temp/Hum Sensor - HTU21D
send: 5-5-0-0 s=255,c=3,t=12,pt=0,l=3,sg=0,st=ok:1.1
send: 5-5-0-0 s=0,c=0,t=6,pt=0,l=0,sg=0,st=ok:
send: 5-5-0-0 s=1,c=0,t=7,pt=0,l=0,sg=0,st=ok:
send: 5-5-0-0 s=2,c=0,t=13,pt=0,l=0,sg=0,st=ok:
Init complete, id=5, parent=0, distance=1
TempDiff :971.94
HumDiff  :0.02
T: 26.06
H: 36.72
send: 5-5-0-0 s=0,c=1,t=0,pt=7,l=5,sg=0,st=ok:26.1
send: 5-5-0-0 s=1,c=1,t=1,pt=7,l=5,sg=0,st=ok:36.7

[Anticimex]

@alexsh1 I'm really glad to hear that. Thank you! Glad that signing is being used and is perceived as something not to complicated to bother with. It sets us apart from many other projects dealing with the same thing :)

[alexsh1]

@Anticimex I did not say it was not complicated :)
Just kidding - speaking just for myself, it did require some time investment to understand the concept and then upgrading my gateway and my nodes (I am still in the process of rolling signing across the rest of my nodes) to MySensors 2.0b. I probably spent more time upgrading MySensors lib and breaking some hardware in the meantime (the SMA connector on the nrf24l01+ PA+LNA) than the actual signing.

[Anticimex]

@alexsh1 yeah, well if there is room for improvement in the documentation then feel free to help put with suggestions if there is anything unclear about that :) I use doxygen to document signing features, and a link is available on the GitHub "front-page" (the readme.md)

[alexsh1]

@Anticimex I think a noob's section would be good. Having said that, the point is that signing is not something beginners should touch. What do you think?

How about a section on the web-site? Somewhere here - https://www.mysensors.org/build/

[Anticimex]

@alexsh1 hm, yeah, perhaps something for @hek to consider. At least a link to the signing section of the doxygen docs could be placed there. I have tried to make the documentation as step-by-step friendly as I can. That said, as I also did the actual implementation, I may well be blind for certain aspects I take for granted that a "novice" does not.

[hek]

The next release of the main site will be much more flexible and integrated with openhardware-added projects. The idea is to allow community members to maintain their projects and/or "articles" themselves. The how-to for signing is a good example of an article.

[Fabien]

This tutorial is up to date for 2.0 release ?

[Anticimex]

@Fabien Yes, top post is now updated for 2.0.0. Documentation is in doxygen.

[Fabien]

Thank you @Anticimex I will update my network soon and had RFM69 Encryption too.