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This was answered on the Gist in a comment[0] linking to a tweet[1]: Things to do instead of shipping TLS certs and static private keys to consumer-grade route

This was answered on the Gist in a comment[0] linking to a tweet[1]: Things to do instead of shipping TLS certs and static private keys to consumer-grade routers you sell by the thousand: Generate a unique keypair per device. Use this keypair to communicate upstream, in a similar fashion to CloudFlare's Keyless SSL. This keypair you generate on the device would need to be preloaded at the factory, unique per device, and the public key would need to be stored in a database. When a TLS handshake comes in, you verify the entire request is signed by that keypair before signing it. Delegated online signing for a TLS handshake isn't even in the top 10 engineering challenges for cryptography in the 2020s. Oh, and, if you don't have connectivity to upstream and your need users to connect to configure something? Fallback to HTTP reachable via port 80 on the private IP for the server. [0] https://gist.github.com/nstarke/a611a19aab433555e91c656fe1f030a9#gistcomment-3145485 https://gist.github.com/nstarke/a611a19aab433555e91c656fe1f0... [1] https://twitter.com/CiPHPerCoder/status/1219228544548720640 https://twitter.com/CiPHPerCoder/status/1219228544548720640

zonidjan 7y ago
> Fallback to HTTP reachable via port 80 on the private IP for the server. How, exactly, is that better than using a common cert? What threat do you propose that applies to HTTPS with a shared cert, and not to HTTP?
lima 7y ago
An attacker can just dump the unique key, impersonate the device and use that for a MitM attack. There's just no way to do this securely without completely locking down the devices using hardware key management (which would be unreasonably expensive for a cheap router, plus bad for people who want to flash their own firmware). Same level of security, and a lot of extra complexity and cost.
- oarsinsync 7y ago
  Yep, and that compromises that one device in the field. Not every device globally, today and tomorrow.
  - lima 7y ago
    Only if each device has a unique subdomain.

zonidjan 7y ago

> Fallback to HTTP reachable via port 80 on the private IP for the server. How, exactly, is that better than using a common cert? What threat do you propose that applies to HTTPS with a shared cert, and not to HTTP?

lima 7y ago

An attacker can just dump the unique key, impersonate the device and use that for a MitM attack. There's just no way to do this securely without completely locking down the devices using hardware key management (which would be unreasonably expensive for a cheap router, plus bad for people who want to flash their own firmware). Same level of security, and a lot of extra complexity and cost.

oarsinsync 7y ago
Yep, and that compromises that one device in the field. Not every device globally, today and tomorrow.
- lima 7y ago
  Only if each device has a unique subdomain.