3 ms·

> You can't exactly make a wifi doorbell, or wifi thermostat, or wifi lightbulb, or wifi security camera, without storing a wifi password. Sure you could. It w

by zrm 6y ago

> You can't exactly make a wifi doorbell, or wifi thermostat, or wifi lightbulb, or wifi security camera, without storing a wifi password. Sure you could. It would just require the access point to provide a passwordless guest network for such devices to use, and then encrypt the traffic end to end for the actual security.

shawnz 6y ago
You would have to store some kind of key material though.
- zrm 6y ago
  Nope, the client device only needs the server's public key, which isn't a secret. The session keys are a secret but they're also different for every device, transient and never written to permanent storage.
  - creeble 6y ago
    Then any device can connect to that server, not just authorized devices. Maybe you assume that's okay, but it's an attack vector on the server, and it means someone can emulate a device that isn't really one.
    - zrm 6y ago
      The device can identify itself with a UUID, which isn't key material and doesn't allow anyone to break the channel between the actual device and the server, which is still authenticated by the client using the server's public key. The attacker could generate a random UUID and connect to the server, but then it just shows up as an unconfigured device and gets ignored. The attacker would have to extract the UUID from the device it wanted to impersonate, which still wouldn't allow it to impersonate any other device the same way a WiFi password does, and would then be detectable because there would be two devices claiming to have the same UUID, at which point you generate a new one for the real device after addressing whatever allowed the attacker to extract it to begin with.
ClumsyPilot 6y ago
So now: A) routers must support network isolated guest network B) anyome can connect to my internet to download stuff C) if my compuer and IoT hub is on my main network, and the lightbulb is on the guest one, how do they talk? Through the third party server? What if there is no internet, I can't control my lights? The actual solution is to have individualised passwords for each device that can be revoked, isolated, etc. Those features are not found in 'normal' wifi routers
- MayeulC 6y ago
  Why would that network need to provide internet connectivity? Have the Wi-Fi gateway perform the authentication and provide an interface, or use a vlan connected to a server that handles that. > Those features are not found in 'normal' wifi routers Then deplore the state of current consumer wi-fi routers and protocols. We can do better than this. More to the point, Wi-Fi wasn't really designed for this, so maybe a new kind of extension is warranted (like NAN, P2P, mesh, etc). Or use another protocol: Zigbee, Lora, z-wave, etc. These generally have the guarantees you want, sometimes do mesh networking, etc. In the past, I've used a raspberrypi3 as a "IoT hub", using its wi-fi network to connect "smart" devices. The third-party server was my hub. Everything works without internet. The dedicated wi-fi network doesn't have internet. You can even lower the bandwidth to 20 MHz, and 1Mbps to achieve greater ranges on that channel.
- octorian 6y ago
  > if my compuer and IoT hub is on my main network, and the lightbulb is on the guest one, how do they talk? If your IoT devices aren't on the same subnet as your smartphone or computer, the vast majority of their "frontend apps" are already DOA. If you're lucky, those apps might let you explicitly specify the device's IP address (in a half-baked fashion that still doesn't work very well).

by zrm 6y ago

shawnz 6y ago

You would have to store some kind of key material though.

zrm 6y ago
Nope, the client device only needs the server's public key, which isn't a secret. The session keys are a secret but they're also different for every device, transient and never written to permanent storage.
- creeble 6y ago
  Then any device can connect to that server, not just authorized devices. Maybe you assume that's okay, but it's an attack vector on the server, and it means someone can emulate a device that isn't really one.
  - zrm 6y ago
    The device can identify itself with a UUID, which isn't key material and doesn't allow anyone to break the channel between the actual device and the server, which is still authenticated by the client using the server's public key. The attacker could generate a random UUID and connect to the server, but then it just shows up as an unconfigured device and gets ignored. The attacker would have to extract the UUID from the device it wanted to impersonate, which still wouldn't allow it to impersonate any other device the same way a WiFi password does, and would then be detectable because there would be two devices claiming to have the same UUID, at which point you generate a new one for the real device after addressing whatever allowed the attacker to extract it to begin with.

ClumsyPilot 6y ago

So now: A) routers must support network isolated guest network B) anyome can connect to my internet to download stuff C) if my compuer and IoT hub is on my main network, and the lightbulb is on the guest one, how do they talk? Through the third party server? What if there is no internet, I can't control my lights? The actual solution is to have individualised passwords for each device that can be revoked, isolated, etc. Those features are not found in 'normal' wifi routers

MayeulC 6y ago
Why would that network need to provide internet connectivity? Have the Wi-Fi gateway perform the authentication and provide an interface, or use a vlan connected to a server that handles that. > Those features are not found in 'normal' wifi routers Then deplore the state of current consumer wi-fi routers and protocols. We can do better than this. More to the point, Wi-Fi wasn't really designed for this, so maybe a new kind of extension is warranted (like NAN, P2P, mesh, etc). Or use another protocol: Zigbee, Lora, z-wave, etc. These generally have the guarantees you want, sometimes do mesh networking, etc. In the past, I've used a raspberrypi3 as a "IoT hub", using its wi-fi network to connect "smart" devices. The third-party server was my hub. Everything works without internet. The dedicated wi-fi network doesn't have internet. You can even lower the bandwidth to 20 MHz, and 1Mbps to achieve greater ranges on that channel.
octorian 6y ago
> if my compuer and IoT hub is on my main network, and the lightbulb is on the guest one, how do they talk? If your IoT devices aren't on the same subnet as your smartphone or computer, the vast majority of their "frontend apps" are already DOA. If you're lucky, those apps might let you explicitly specify the device's IP address (in a half-baked fashion that still doesn't work very well).