[security] Introducing signing support to MySensors

[Anticimex]

Yes.

[ahmedadelhosni]

@Anticimex mmmm
Can't it be implemented in a way so that whitelist is to be defined by the controller ?
For example, an internal message to be used to set the data.

My concern is that auto assignation of nodes is flexible but at the same time you may need to choose which sensor node to be added to your whitelist. Thus if a Controller can show you all your nodes, like vera or domoticz, I guess this option can be added to the plugin to send an internal message to the GW to choose which sensor node to be added.

Am I saying something logic ? :)

[Anticimex]

Possibly. But that would mean that security features is dictaded by the controller plugins and I do not like that at all.

For months I have been trying to convince the Domoticz people that their ACK timeout is way to short and needs to be configurable for signing to work with Domoticz, but they do not even reply to me.

And I do not trust controllers at all and want to have full control over all configuration aspects of the signing solution. So I do not think it is good to move that logic off the nodes (whitelisting can also be used by a node, communicating with another node).

It is not only a GW that can have a whitelist. So although it might have been flexible to have it configurable, I think it compromises security (who knows, your controller could be hacked to inject a whitelist that permits a rogue node in your network).

Of course, security is at some level compromised anyway if the controller is hacked. But it is not the signing solution that is compromised in this case.

And ultimately, that feature would mean that the level of signing security and signing features for MySensors, becomes controller specific. And that I do not think is a good idea. If I want to change or improve the feature, the controller plugins all also have to be updated. It just becomes a too big turnaround for something as important as this in my opinion.

[ahmedadelhosni]

Yeah I got your point of view and convinced me. The only solution to implement this is that other communities works together to improve flexibility and security. This is not that easy of course as you have said.

Thanks a lot for your time.

[Anticimex]

Thanks for understanding :)

[ahmedadelhosni]

Also in all cases I see that if your controller is being hacked there will be no use to play with the whitelist :) The attacker has full control already to blow my house if he wants to :)

Anyway maybe I need to reflash using signing to understand things more.

Keep it up :)

[ahmedadelhosni]

Hi again.

I managed to set run the softsign and everything seems fine till now. I just want to understand the system much more if you please.

Now my Gateway sends this data when I turn on Light.
( I am using GatewayW5100 with Domoticz ) Development branch

0;0;3;0;9;Eth: 0;0;3;0;18;PING
0;0;3;0;9;Eth: 2;7;1;0;2;1
0;0;3;0;9;send: 0-0-2-2 s=7,c=3,t=16,pt=0,l=0,sg=0,st=ok:
0;0;3;0;9;read: 2-2-0 s=255,c=3,t=17,pt=6,l=25,sg=0:01F470C061A0B9FF3DE248835736E2B85E31C8D6D1844AACAC
0;0;3;0;9;Signing backend: ATSHA204Soft
0;0;3;0;9;Message to process: 00020E01020731
0;0;3;0;9;Current nonce: 01F470C061A0B9FF3DE248835736E2B85E31C8D6D1844AACACAAAAAAAAAAAAAA
0;0;3;0;9;HMAC: 135DBD85528E869ECC86C9C53679795D7FDA7B789DB7A0A74053C94FE8D668F0
0;0;3;0;9;Signature in message: 015DBD85528E869ECC86C9C53679795D7FDA7B789DB7A0A7
0;0;3;0;9;send: 0-0-2-2 s=7,c=1,t=2,pt=0,l=1,sg=1,st=ok:1

I want to know how was the following data calculated please:

• sg=0:01F470C061A0B9FF3DE248835736E2B85E31C8D6D1844AACAC
• Message to process: 00020E01020731
• Current nonce: 01F470C061A0B9FF3DE248835736E2B85E31C8D6D1844AACACAAAAAAAAAAAAAA
• HMAC: 135DBD85528E869ECC86C9C53679795D7FDA7B789DB7A0A74053C94FE8D668F0
• Signature in message: 015DBD85528E869ECC86C9C53679795D7FDA7B789DB7A0A7

So how was sg= calculated ?
What is message to process ?
The nonce is depending on analogue signal + what ? to get this value ?
I have already defined a random HMAC, but this one is different. It is a combination of what ?
Finally what is signature in message ?

On the other side I am trying to sniff the data by a serialgateway which is trying to hack the network. It only read the following data:

0;0;3;0;9;read: 2-2-0 s=255,c=3,t=17,pt=6,l=25,sg=0:01F470C061A0B9FF3DE248835736E2B85E31C8D6D1844AACAC                      
2;255;3;0;17;01F470C061A0B9FF3DE248835736E2B85E31C8D6D1844AACAC

It is the sg only which it succeeded to read. Also I do understood form the topic that the attacker can read values sent between nodes unencrypted, but here I can't figure out where is the unencrypted data which can be sniffed by the attacker but we don't bother ourselves with cas we protect our network by using signing.

Lots of questions but I am trying to understand the logic and architecture in details to understand what I am doing :)

Thanks a lot.

[Anticimex]

Hi,
I suggest you read the doxygen documentation for signing carefully as it answers the questions you have. Signing does not in any way prevent anyone from reading your messages. As I have described in the documentation, it provides authenticity. That is, you can trust the sender of a signed message to be yours and not someone else's.

[ahmedadelhosni]

@Anticimex Yeah I understand it doesn't prevent anyone from reading my messages, and that's what I am trying to do now. To hack the system depending on the data available. But when I read the post I understood that encryption is not a priority as signing is enough now to prevent an attacker from sending data, but it can read text. I thought I will find clear text describing that I am sending to node X value Y but I found this 2;255;3;0;17;01F470C061A0B9FF3DE248835736E2B85E31C8D6D1844AACAC
so I wanted to ask.

Anyway I'll re read the documents more carefully and return to you back please. Thanks.

[Anticimex]

Encryption is available for both rf24 and rf69 radios. But encryption and signing are two different things, and I work with signing. And signing is more efficient against hackers than encryption. Encryption is more if you care about privacy.

[noelgeorgi]

@Anticimex @hek is it possible to encrypt the data sent over nrf modules using this https://github.com/DavyLandman/AESLib ???

[Anticimex]

@noelgeorgi AES encryption is already supported for both NRF24 and RFM69 radios. See MyConfig.h on the development branch for the flag to use. Doyxgen documentation I link to in this thread on the topic post also contain the personalization instructions for encryption on the development branch.

[noelgeorgi]

@Anticimex said:

@noelgeorgi AES encryption is already supported for both NRF24 and RFM69 radios. See MyConfig.h on the development branch for the flag to use. Doyxgen documentation I link to in this thread on the topic post also contain the personalization instructions for encryption on the development branch.

Thanks for the info.
I'm getting the following errors when compiling securitypersonalizer:

Arduino: 1.6.7 (Linux), Board: "Arduino/Genuino Mega or Mega 2560, ATmega2560 (Mega 2560)"

/home/technoman/Arduino/libraries/MySensors/examples/SecurityPersonalizer/SecurityPersonalizer.ino:83:28: fatal error: sha204_library.h: No such file or directory
 #include <sha204_library.h>
                            ^
compilation terminated.
exit status 1
Error compiling.

  This report would have more information with
  "Show verbose output during compilation"
  enabled in File > Preferences.

doesnt the ATSHA204 library has ATSHA204.h

[Anticimex]

@noelgeorgi master or development branch?

[noelgeorgi]

@Anticimex development branch

[Anticimex]

@noelgeorgi have you made changes to the sketch? Jenkins builds it without problems.

[noelgeorgi]

@Anticimex no, I'm using the sketch from the examples.....:confused:
am i missing some libraries????

[Anticimex]

@noelgeorgi if you have cloned the arduino git you have everything you need. I can build that sketch myself and have used it many times. I suspect you have a problem with your environment if you get compilation errors in it. We continously test the repository and build all examples nightly to make sure it all works as it is supposed to. You can see this at ci.mysensors.org

[noelgeorgi]

@Anticimex sorry for the interruption, i was using rsync to get eveything synced and i might have messed something uop, sha204 library was missing from my libraries folder, now everything works, thanks for the prompt and fast support.

[Anticimex]

:thumbsup: