[security] Introducing signing support to MySensors

Anticimex

@ahmedadelhosni the integrity check that could emit a TAMPERED message is intended to ensure that signing backend does not use corrupted data.
This is done by having the personalizer calculate a checksum of the data it wrote. Then the signing backend validates the data read against the checksum and of there is a mismatch then it reports that personalization has been tampered.
This is to ensure that users don't get confused by signing not working if they have accidentally erased or manipulated the personalization data.

Proyectos Integrasoft

Hello! I'm new to this and I've been using MySensors to communicate a few nodes in my house with a gateway ... Everything I've done without problems until now that I want to sign the data ...

I have done the following:

Ah my sketch (node) simply added the following statement:

#define MY_SIGNING_SOFT
#define MY_SIGNING_REQUEST_SIGNATURES
#define MY_SIGNING_SOFT_RANDOMSEED_PIN A3
(It's a mini pro 3.3 v)

My GW added this:
#define MY_SIGNING_SOFT
#define MY_SIGNING_REQUEST_SIGNATURES
#define MY_SIGNING_SOFT_RANDOMSEED_PIN A7
(Nano 5v)

and already ... everything else I left it still, as I was working.

Now ... This is what the log of my node shows me:

0 MCO:BGN:INIT NODE,CP=RNNNAS-,VER=2.1.1
4 TSM:INIT
4 TSF:WUR:MS=0
12 TSM:INIT:TSP OK
14 TSM:INIT:STATID=110
16 TSF:SID:OK,ID=110
18 TSM:FPAR
55 TSF:MSG:SEND,110-110-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
698 TSF:MSG:READ,0-0-110,s=255,c=3,t=8,pt=1,l=1,sg=0:0
704 TSF:MSG:FPAR OK,ID=0,D=1
2064 TSM:FPAR:OK
2064 TSM:ID
2066 TSM:ID:OK
2068 TSM:UPL
2074 TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=24,pt=1,l=1,sg=0,ft=0,st=OK:1
2084 TSF:MSG:READ,0-0-110,s=255,c=3,t=25,pt=1,l=1,sg=0:1
2091 TSF:MSG:PONG RECV,HP=1
2093 TSM:UPL:OK
2095 TSM:READY:ID=110,PAR=0,DIS=1
2119 TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=15,pt=6,l=2,sg=0,ft=0,st=OK:0101
2129 TSF:MSG:READ,0-0-110,s=255,c=3,t=15,pt=6,l=2,sg=0:0101
2154 TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=16,pt=0,l=0,sg=0,ft=0,st=OK:
2177 TSF:MSG:READ,0-0-110,s=255,c=3,t=17,pt=6,l=25,sg=0:543E0871819CBE4290536346F5231CBEF4C8F70A344B289CEA
2394 !TSF:MSG:SEND,110-110-0-0,s=255,c=0,t=17,pt=0,l=5,sg=1,ft=0,st=NACK:2.1.1
2451 !TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=16,pt=0,l=0,sg=1,ft=1,st=NACK:
2459 !TSF:MSG:SIGN FAIL
4509 !TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=16,pt=0,l=0,sg=1,ft=3,st=NACK:
4517 !TSF:MSG:SIGN FAIL
4569 !TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=16,pt=0,l=0,sg=1,ft=5,st=NACK:
4577 !TSF:MSG:SIGN FAIL
4612 TSF:MSG:SEND,110-110-0-0,s=2,c=3,t=16,pt=0,l=0,sg=1,ft=7,st=OK:
4632 TSF:MSG:READ,0-0-110,s=255,c=3,t=17,pt=6,l=25,sg=1:5D4997715396BEFB979106A93EF22C9E1DBAE516012E040FAE
4851 !TSF:MSG:SEND,110-110-0-0,s=2,c=0,t=3,pt=0,l=11,sg=1,ft=0,st=NACK:Water Valve
4909 !TSF:MSG:SEND,110-110-0-0,s=1,c=3,t=16,pt=0,l=0,sg=1,ft=1,st=NACK:
4915 !TSF:MSG:SIGN FAIL
4966 !TSF:MSG:SEND,110-110-0-0,s=3,c=3,t=16,pt=0,l=0,sg=1,ft=3,st=NACK:
4974 !TSF:MSG:SIGN FAIL
5025 !TSF:MSG:SEND,110-110-0-0,s=4,c=3,t=16,pt=0,l=0,sg=1,ft=5,st=NACK:
5033 !TSF:MSG:SIGN FAIL
5083 !TSF:MSG:SEND,110-110-0-0,s=5,c=3,t=16,pt=0,l=0,sg=1,ft=7,st=NACK:
5091 !TSF:MSG:SIGN FAIL
5142 !TSF:MSG:SEND,110-110-0-0,s=6,c=3,t=16,pt=0,l=0,sg=1,ft=9,st=NACK:
5150 !TSF:MSG:SIGN FAIL
5199 !TSF:MSG:SEND,110-110-0-0,s=7,c=3,t=16,pt=0,l=0,sg=1,ft=11,st=NACK:
5208 !TSF:MSG:SIGN FAIL
5212 MCO:REG:REQ
5261 !TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=26,pt=1,l=1,sg=1,ft=13,st=NACK:2
5269 !TSM:READY:UPL FAIL,SNP
5273 TSM:FPAR
5308 TSF:MSG:SEND,110-110-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=14,st=OK:
7270 !TSF:SND:TNR
7319 !TSM:FPAR:NO REPLY
7321 TSM:FPAR
7358 TSF:MSG:SEND,110-110-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
8204 TSF:MSG:READ,0-0-110,s=255,c=3,t=8,pt=1,l=1,sg=0:0
8210 TSF:MSG:FPAR OK,ID=0,D=1
9271 !TSF:SND:TNR
9367 TSM:FPAR:OK
9367 TSM:ID
9369 TSM:ID:OK
9371 TSM:UPL
9375 TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=24,pt=1,l=1,sg=0,ft=0,st=OK:1
9385 TSF:MSG:READ,0-0-110,s=255,c=3,t=25,pt=1,l=1,sg=0:1
9392 TSF:MSG:PONG RECV,HP=1
9394 TSM:UPL:OK
9396 TSM:READY:ID=110,PAR=0,DIS=1
9412 TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=15,pt=6,l=2,sg=0,ft=0,st=OK:0101
9420 TSF:MSG:READ,0-0-110,s=255,c=3,t=15,pt=6,l=2,sg=0:0101
9457 TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=16,pt=0,l=0,sg=1,ft=0,st=OK:
9480 TSF:MSG:READ,0-0-110,s=255,c=3,t=17,pt=6,l=25,sg=1:20169962FD569DAE7F6D69702C2AD69B8492264A3FC2450E50
9697 !TSF:MSG:SEND,110-110-0-0,s=255,c=0,t=17,pt=0,l=5,sg=1,ft=0,st=NACK:2.1.1
9754 !TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=16,pt=0,l=0,sg=1,ft=1,st=NACK:
9762 !TSF:MSG:SIGN FAIL
11812 !TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=16,pt=0,l=0,sg=1,ft=3,st=NACK:
11821 !TSF:MSG:SIGN FAIL
11872 !TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=16,pt=0,l=0,sg=1,ft=5,st=NACK:
11880 !TSF:MSG:SIGN FAIL
11931 !TSF:MSG:SEND,110-110-0-0,s=2,c=3,t=16,pt=0,l=0,sg=1,ft=7,st=NACK:
11939 !TSF:MSG:SIGN FAIL
11988 !TSF:MSG:SEND,110-110-0-0,s=1,c=3,t=16,pt=0,l=0,sg=1,ft=9,st=NACK:
11997 !TSF:MSG:SIGN FAIL
12048 !TSF:MSG:SEND,110-110-0-0,s=3,c=3,t=16,pt=0,l=0,sg=1,ft=11,st=NACK:
12056 !TSF:MSG:SIGN FAIL
12107 !TSF:MSG:SEND,110-110-0-0,s=4,c=3,t=16,pt=0,l=0,sg=1,ft=13,st=NACK:
12115 !TSF:MSG:SIGN FAIL
12167 !TSF:MSG:SEND,110-110-0-0,s=5,c=3,t=16,pt=0,l=0,sg=1,ft=15,st=NACK:
12175 !TSF:MSG:SIGN FAIL
12224 !TSF:MSG:SEND,110-110-0-0,s=6,c=3,t=16,pt=0,l=0,sg=1,ft=1,st=NACK:
12232 !TSF:MSG:SIGN FAIL
12283 !TSF:MSG:SEND,110-110-0-0,s=7,c=3,t=16,pt=0,l=0,sg=1,ft=3,st=NACK:
12292 !TSF:MSG:SIGN FAIL
12294 MCO:REG:REQ
12343 TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=26,pt=1,l=1,sg=1,ft=5,st=OK:2
12351 TSF:MSG:READ,0-0-110,s=255,c=3,t=16,pt=0,l=0,sg=0:
12435 !TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=17,pt=6,l=25,sg=0,ft=0,st=NACK:EC4D4496E138DD8C83E9837D130B8AD51D0B5BE66E9CC103EB14399 !TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=26,pt=1,l=1,sg=1,ft=1,st=NACK:2
16427 TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=26,pt=1,l=1,sg=1,ft=2,st=OK:2
16437 TSF:MSG:READ,0-0-110,s=255,c=3,t=16,pt=0,l=0,sg=0:
16519 TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=17,pt=6,l=25,sg=0,ft=0,st=OK:CE22C6ECF337A5713AD0677785547E59FB49FB964B79EFAB88
16609 TSF:MSG:READ,0-0-110,s=255,c=3,t=27,pt=1,l=1,sg=1:1
16773 !TSF:MSG:SIGN VERIFY FAIL
16777 TSF:MSG:READ,0-0-110,s=255,c=3,t=27,pt=1,l=1,sg=1:1
16783 !TSF:MSG:SIGN VERIFY FAIL
16787 MCO:BGN:STP
16836 !TSF:MSG:SEND,110-110-0-0,s=1,c=3,t=16,pt=0,l=0,sg=1,ft=0,st=NACK:
16844 !TSF:MSG:SIGN FAIL
16896 !TSF:MSG:SEND,110-110-0-0,s=2,c=3,t=16,pt=0,l=0,sg=1,ft=2,st=NACK:
16904 !TSF:MSG:SIGN FAIL
16906 MCO:BGN:INIT OK,TSP=1
Valve Change Detected ,
Reporting battery
Main Battery reported: 1076
16959 !TSF:MSG:SEND,110-110-0-0,s=6,c=3,t=16,pt=0,l=0,sg=1,ft=4,st=NACK:
16967 !TSF:MSG:SIGN FAIL
Bridge Battery reported: 0
17018 !TSF:MSG:SEND,110-110-0-0,s=7,c=3,t=16,pt=0,l=0,sg=1,ft=6,st=NACK:
17027 !TSF:MSG:SIGN FAIL
next BATT report TIME selected
17037 TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=16,pt=0,l=0,sg=1,ft=8,st=OK:
17059 TSF:MSG:READ,0-0-110,s=255,c=3,t=17,pt=6,l=25,sg=1:A49B044E02033467D7D7220BA28FBFEA6C9ED2EFA7C4DE16CD
17276 !TSF:MSG:SEND,110-110-0-0,s=255,c=3,t=0,pt=1,l=1,sg=1,ft=0,st=NACK:100
Both to Low in Bridge .....

And this is what the log of the GW shows me:

0;255;3;0;9;TSF:MSG:READ,110-110-255,s=255,c=3,t=7,pt=0,l=0,sg=0:
0;255;3;0;9;TSF:MSG:BC
0;255;3;0;9;TSF:MSG:FPAR REQ,ID=110
0;255;3;0;9;TSF:PNG:SEND,TO=0
0;255;3;0;9;TSF:CKU:OK
0;255;3;0;9;TSF:MSG:GWL OK
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=8,pt=1,l=1,sg=0,ft=0,st=OK:0
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=255,c=3,t=24,pt=1,l=1,sg=0:1
0;255;3;0;9;TSF:MSG:PINGED,ID=110,HP=1
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=25,pt=1,l=1,sg=0,ft=0,st=OK:1
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=255,c=3,t=15,pt=6,l=2,sg=0:0101
0;255;3;0;9;!TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=15,pt=6,l=2,sg=0,ft=0,st=NACK:0101
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=255,c=3,t=16,pt=0,l=0,sg=0:
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=17,pt=6,l=25,sg=0,ft=0,st=OK:E36F33C7F0FAB62159035EE11FBC031CE96304C15907FCA866
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=255,c=3,t=16,pt=0,l=0,sg=1:
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=17,pt=6,l=25,sg=1,ft=0,st=OK:9CB25AA3C9DDAA7EB1D4EC4FEE49B3ADDA743FB87AC1844809
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=255,c=3,t=6,pt=1,l=1,sg=1:0
0;255;3;0;9;!TSF:MSG:SIGN VERIFY FAIL
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=255,c=3,t=16,pt=0,l=0,sg=1:
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=17,pt=6,l=25,sg=1,ft=0,st=OK:A2FFF069812565DE86C4BE5517F7F497141208817C51412562
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=255,c=3,t=16,pt=0,l=0,sg=1:
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=17,pt=6,l=25,sg=1,ft=0,st=OK:F2503A2DF3D42714F93FF7386FC7E4087E6FFC31B86D0449BF
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=255,c=3,t=12,pt=0,l=3,sg=1:2.3
0;255;3;0;9;!TSF:MSG:SIGN VERIFY FAIL
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=2,c=3,t=16,pt=0,l=0,sg=1:
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=17,pt=6,l=25,sg=1,ft=0,st=OK:3DB72D0ECA0E7C5546CB68782E93D66A0BA86F7DBD05714798
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=2,c=0,t=3,pt=0,l=11,sg=1:Water Valve
0;255;3;0;9;!TSF:MSG:SIGN VERIFY FAIL
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=1,c=3,t=16,pt=0,l=0,sg=1:
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=17,pt=6,l=25,sg=1,ft=0,st=OK:272DE6ED5FDDDB14B704CF36D32DA37D3A3C32D4F7F30E4D86
0;255;3;0;9;TSF:MSG:READ,110-110-255,s=255,c=3,t=7,pt=0,l=0,sg=0:
0;255;3;0;9;TSF:MSG:BC
0;255;3;0;9;TSF:MSG:FPAR REQ,ID=110
0;255;3;0;9;TSF:PNG:SEND,TO=0
0;255;3;0;9;TSF:CKU:OK
0;255;3;0;9;TSF:MSG:GWL OK
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=8,pt=1,l=1,sg=0,ft=0,st=OK:0
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=255,c=3,t=24,pt=1,l=1,sg=0:1
0;255;3;0;9;TSF:MSG:PINGED,ID=110,HP=1
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=25,pt=1,l=1,sg=0,ft=0,st=OK:1
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=255,c=3,t=15,pt=6,l=2,sg=0:0101
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=15,pt=6,l=2,sg=0,ft=0,st=OK:0101
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=255,c=3,t=16,pt=0,l=0,sg=1:
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=17,pt=6,l=25,sg=1,ft=0,st=OK:05E7E841D621BB9E5F323082CBF40509B1B9D100C6EF955156
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=255,c=3,t=16,pt=0,l=0,sg=1:
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=17,pt=6,l=25,sg=1,ft=0,st=OK:89A2A933A3310EE14AF048E3A786FD1432608BBD361B366DC0
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=2,c=3,t=16,pt=0,l=0,sg=1:
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=17,pt=6,l=25,sg=1,ft=0,st=OK:554A491A49FA49B278B8269CEF0748346A9980A395161F3356
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=1,c=3,t=16,pt=0,l=0,sg=1:
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=17,pt=6,l=25,sg=1,ft=0,st=OK:6220CC178F89ADD1F7AC819695C344770835A96CBAFB2D6848
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=6,c=3,t=16,pt=0,l=0,sg=1:
0;255;3;0;9;TSF:MSG:SEND,0-0-110-110,s=255,c=3,t=17,pt=6,l=25,sg=1,ft=0,st=OK:DA701B4D253E0FC19BB7FA0D2699D1C9CE7F7E7B89586ED8A2
0;255;3;0;9;TSF:MSG:READ,110-110-0,s=6,c=0,t=30,pt=0,l=15,sg=1:Main Batt Volts
0;255;3;0;9;!TSF:MSG:SIGN VERIFY FAIL

Can you help me please!?
I read everything about the signed but the truth I am somewhat confused ... If you could provide me a sketch of a node and a gateway that work for me to guide me I would appreciate it.

Thank you very much in advance!

Anticimex

@Proyectos-Integrasoft Hi, as mentioned several places, signing makes messages be a lot bigger and that puts strain on the radio link. You can see many NACKs in the log which means messages don't get through. That's way signing fail. You need to make sure you have properly decoupled radio modules and a solid power supply.

Anticimex

@Proyectos-Integrasoft another thing you did not mention is if you have personalized your nodes? Signing require personalization to store certain data. Please read the documentation (linked on the top of this thread).

Proyectos Integrasoft

@Anticimex Thnks!

As you can see in the sketch, I'm using a Nrf24L01 module for the node and for the gateway. They are connected to their designed boards (Node and Gateway) respectively. The power, for now, I am doing through the Ftdi232 that I use to connect it to the PC to do debugging. Before adding the signature to the sketch, they were working perfect. What do you suggest doing then?

Also, I have read about the customization of the nodes, but I feel honest I have not managed to understand how to do it ... Could you explain me easily how to personalize it? Truthfully, I have not been able to use the guide.

Thanks for answering me! : D

Anticimex

@Proyectos-Integrasoft then please let me know what parts are unclear. I try to make it as easy to follow as possible. You can also read the beta documentation but be aware that personalization has been rewritten on the beta track. I have provided a step by step instruction for personalization in the signing module in the documentation. It should give you all information needed.
Regarding powering, have you followed the guides available here in the forum for powering the radio? NACKs is not a signing problem. It is a radio problem.

Proyectos Integrasoft

@Anticimex What I understand is the following:

I must choose the backend that I am going to use. (In my case, I'll use the software firm)
Then I must choose a free pin to establish a random seed for the pseudorandom generator. (In my case I chose pin A3 that is completely free on the plate).
Then I request that all the messages that enter the node will be signed. (I do this using MY_SIGNING_REQUEST_SIGNATURES on the gateway and on the node)
finally says that if I am not going to use MY_SIGNING_SIMPLE_PASSWD, I need to customize the node. This is where I get confused ...

First of all, ask me to enable GENERATE_KEYS_SOFT, saying that this will provide random keys for HMAC and AES, and that I should copy and replace them in the corresponding definitions in "User-defined key data". What do you mean by "user-defined key data"? When I enable this, in the LOG of my node nothing strange comes out, the same thing I posted previously.

Second, you tell me to disable the key generator by software and enable the PERSONALIZE_SOFT ... And that this will keep the keys in the EEPROM ... When you talk about enabling and disabling you mean that I must burn the sketch first with Generate_Keys_Soft and then burn again but now with the hmac and aes keys that were generated, while enabling the Personalize_Soft?

This is what I do not understand. I do not get the keys with the GENERATE_KEYS_SOFT ... And I do not clearly understand what I should do next.

You apologize for my lack of knowledge or understanding. And I thank you for your help.

Proyectos Integrasoft

@Anticimex And as for the radio. I followed the connection guide that comes out at https://www.mysensors.org/build/serial_gateway, even watching the video. I do not know if you mean another guide? If so, could you give me the link? Thank you for your collaboration.

Anticimex

@Proyectos-Integrasoft I assume you use an official release first of all. That personalization is more complicated than the one used on beta/development branch.
Then you are first expected to generate the keys (like you say). These keys are printed on the serial console. You then copy those into the personalizer sketch and reconfigure the personalizer to store the keys you have set. And then you run the personalizer to use those keys.
You can of course skip the generation step and set the hmac key manually using the personalizer. The only requirement is the size of the key (32 bytes) and that it is identical on all nodes.

Proyectos Integrasoft

@Anticimex
Could you please give me the link of the last official release? to verify that is the one that I have. When you say "copy" the keys in the sketch personalizer, are you referring to PERSONALIZE_SOFT? And what do you mean by configuring the sketch personalizer? Could you additionally tell me how it would be done manually? (example of sketch)

Anticimex

@Proyectos-Integrasoft I am not sure where to start. I assume you are familiar with c code? The signing solution available in the latest official release (which you find on github, I believe is 2.1.1) require at least fundamental understanding of how to adjust sketch code.
The documentation gives the exact lines to change.
There is, like I said, a step by step guide, and if you follow it you should end up with a properly personalized device. In this case, that is of less importance since you currently do not have a stable enough radio link to use security since you get NACKs for full size payloads (so neither signing nor encryption will work).
So you will have to make that work and get rid of the NACKs, before we should start worrying about personalization.
And like I said before, that is not a signing related issue. You will get the same problem if you try to send full size payloads of any kind. Just try to disable signing and send full size payloads.

Proyectos Integrasoft

@Anticimex
Okay, so I'll start by tackling things step by step ... How can I avoid getting NACKs in my log?

Anticimex

@Proyectos-Integrasoft as I said; ensuring good decoupling, a stable power supply (measure that to confirm). Also, counterfeit RF24 chips are all over the place that perform under par. There are quite a few threads here on this topic. So please post such questions in those, it is somewhat off topic here :)
Also, setting proper power levels can have a huge impact on the performance.

ahmedadelhosni

Hi @Anticimex Actually there is something that I can not understand regarding cryptograhpy. I want to know how other products like Fibaro, Smartthings, etc handles the security ?

Here in our library the SW is not a good idea, why ? I thought beacuse someone can dump the memory .. but is it that easy ? Can't we lock the code and memory ? Also in the hardware ATSHA solution, someone can easily take the chip and intercept our network and sniff it or even send commands as it is explained in the documentation and that's why we don't use security for public nodes as it usualy reports states. But can't we lock the chip ? and by some way only the atmega can communicate with it to get the key by some way ?

I read online that some people are using private and public keys .. if this is the case, then the private key is offcourse saved in the memory. How do they handle this problem ?

Do they use AES , SHA ? which encyption way ?

Also the nRF52, I tried to read a lot and they use private and public keys i guess.

lots of questions and I am confused but I want to know how do they handle protection for public nodes.

Can you please explain this to me ?

Thanks.

Anticimex

@ahmedadelhosni some devices, like the atmega, doss not support locking the memory, so the software based signing is inherently insecure in terms of hw theft.
Atsha204a based signing protection specifically against this because the personalizer locks the chip from readout. It is not possible to extract the hmac key from the atsha204a memory and the key is never transmitted OTA (unless you deploy the personalizer OTA).

Anticimex

@ahmedadelhosni and regarding reusing a node/atsha204a for attack purpose, we have whitelisting to protect against that. The serials used for whitelisting are also never send OTA (again, unless you send the personalizer OTA).

ahmedadelhosni

@Anticimex

1- So if we have a microcontroller that supports locking the memory then the problem is solved ? I know that SAM is being introduced now, Does it support this ?

2- what is then the purpose of locking the ATSHA if we can't extract the HMAC which we depend on it ?

Thanks.

Anticimex

@ahmedadelhosni
We lock the atsha to make sure it can't be readable.
It does not matter that samd supports locking or not. The atmega328p does not. For now, we have a security scheme that supports any target, so we have to have a system that works for all.
For MySensors v3, an entirely new security scheme is under consideration. But it will mean dropping support for the atmga328p as it is not powerful enough.
As for what others do, I suggest you ask them :)
Security can be implemented in many ways. Each with drawbacks and benefits. The one currently in use is a scheme that can work on basically any target with reasonable security and performance. It has drawbacks, yes, but at the time of implementation, these were considered acceptable.
For the future, more sophisticated schemes can be used which are easier to use, arguably more secure but more complex in terms of computational power and protocol. The core team is investigating various solutions.

ahmedadelhosni

@Anticimex Sorry but I didn't understand the benefit of locking the ATSHA to be unreadable ? :expressionless:
I know we do not lock it so that we can read the HMAC and use it during verification, but what is the usage of a locked ATSHA ?

Anticimex

@ahmedadelhosni what do you mean? All cryptography is performed inside the chip. The hmac key never leaves the chip after it has been programmed and locked. Thats the whole point with the atsha204a.

[security] Introducing signing support to MySensors

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