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> But the consequence is that people feel like they are being fleeced when they need another key, because it can cost you hundreds of dollars to pair one. Beca

> But the consequence is that people feel like they are being fleeced when they need another key, because it can cost you hundreds of dollars to pair one. Because the ARE being fleeced. It's an artificial dependency on the vendor on the one hand versus a blatantly insecure approach on the other. Secure pairing that can be done by the end user isn't rocket science.

the_mitsuhiko 1y ago
It is a bit rocket science because cars stand around. The CAN bus can even be externally accessed if you pop open the right part of the car (common fault are adaptive headlights). It is not as trivial as people make it out to be because cars violate one of the most important principles of having good security: no physical access.
- fc417fc802 1y ago
  That has nothing to do with secure pairing. It's an entirely orthogonal concern. Any sensitive system on a vehicle is going to be subject to the same thing. I don't think anyone will be surprised if the security is swiss cheese once you pop the hood open or bust a headlight out. Keep in mind that a brick to the window and tearing up the center console will get you physical access to the head unit on most vehicles.
- IshKebab 1y ago
  It is trivial: 1. Initiate pairing via the entertainment system interface. 2. Use rolling codes. Don't allow rewinding the codes. 3. Add a tiny tiny bit of non-volatile memory in the keys so that batteries can be changed without breaking the key. This is only necessary if the car can't be entered using the physical key, otherwise the user can just open the car with the physical key, turn on the ignition and re-pair the key. I could make a secure system to do this and I'm no crypto genius. (Note this would still be vulnerable to rolljam but that's not a very practical attack, and defeating that is a bit difficult.) To support car hire/share places if they want to prevent users pairing new keys you could allow setting a password on the pairing interface.
  - the_mitsuhiko 1y ago
    That's more or less already how the rolling code based systems work. The problem of course is that if you have access to one of those keys (or use rolljam to get one or more codes) you have enough to get another key added.
    - fc417fc802 1y ago
      That isn't the problem, at least not the major one that lead to this discussion. It's that the algorithm used is broken. It's example number 9001 of why you should never roll your own crypto for a commercial application. (Amusingly example 9002, TETRA radios, was also on the HN frontpage around the same time).
      - the_mitsuhiko 1y ago
        First of all they did not roll their own crypto, it's just not the most modern crypto any more. Secondly while this particular permutation of the issue is related to bad crypto, it's cascading a completely different issue which is that it's just fundamentally possible to pair a key with physical access which is easy to get.
        fc417fc802 1y ago
        From Wikipedia: > KeeLoq is a proprietary hardware-dedicated block cipher that uses a non-linear feedback shift register (NLFSR). Pretty much any proprietary encryption algorithm is going to qualify as "rolling your own". "Not the most modern" is a gross understatement. I can forgive the original authors since it dates to the 1980s and AES wasn't standardized until 2001. (Only just barely though given that DES dates to 1977.) I can't forgive vehicle manufacturers that are _still_ using it (or things significantly like it) 25 years later. I hope that products manufactured post 2005 use strong publicly available cryptography. After 2010 I fully expect it. After 2015 I view any failure in that regard as gross negligence that ought to be legally actionable. > it's just fundamentally possible to pair a key with physical access which is easy to get. I don't follow?

the_mitsuhiko 1y ago

It is a bit rocket science because cars stand around. The CAN bus can even be externally accessed if you pop open the right part of the car (common fault are adaptive headlights). It is not as trivial as people make it out to be because cars violate one of the most important principles of having good security: no physical access.

fc417fc802 1y ago
That has nothing to do with secure pairing. It's an entirely orthogonal concern. Any sensitive system on a vehicle is going to be subject to the same thing. I don't think anyone will be surprised if the security is swiss cheese once you pop the hood open or bust a headlight out. Keep in mind that a brick to the window and tearing up the center console will get you physical access to the head unit on most vehicles.
IshKebab 1y ago
It is trivial: 1. Initiate pairing via the entertainment system interface. 2. Use rolling codes. Don't allow rewinding the codes. 3. Add a tiny tiny bit of non-volatile memory in the keys so that batteries can be changed without breaking the key. This is only necessary if the car can't be entered using the physical key, otherwise the user can just open the car with the physical key, turn on the ignition and re-pair the key. I could make a secure system to do this and I'm no crypto genius. (Note this would still be vulnerable to rolljam but that's not a very practical attack, and defeating that is a bit difficult.) To support car hire/share places if they want to prevent users pairing new keys you could allow setting a password on the pairing interface.
- the_mitsuhiko 1y ago
  That's more or less already how the rolling code based systems work. The problem of course is that if you have access to one of those keys (or use rolljam to get one or more codes) you have enough to get another key added.
  - fc417fc802 1y ago
    That isn't the problem, at least not the major one that lead to this discussion. It's that the algorithm used is broken. It's example number 9001 of why you should never roll your own crypto for a commercial application. (Amusingly example 9002, TETRA radios, was also on the HN frontpage around the same time).
    - the_mitsuhiko 1y ago
      First of all they did not roll their own crypto, it's just not the most modern crypto any more. Secondly while this particular permutation of the issue is related to bad crypto, it's cascading a completely different issue which is that it's just fundamentally possible to pair a key with physical access which is easy to get.
      - fc417fc802 1y ago
        From Wikipedia: > KeeLoq is a proprietary hardware-dedicated block cipher that uses a non-linear feedback shift register (NLFSR). Pretty much any proprietary encryption algorithm is going to qualify as "rolling your own". "Not the most modern" is a gross understatement. I can forgive the original authors since it dates to the 1980s and AES wasn't standardized until 2001. (Only just barely though given that DES dates to 1977.) I can't forgive vehicle manufacturers that are _still_ using it (or things significantly like it) 25 years later. I hope that products manufactured post 2005 use strong publicly available cryptography. After 2010 I fully expect it. After 2015 I view any failure in that regard as gross negligence that ought to be legally actionable. > it's just fundamentally possible to pair a key with physical access which is easy to get. I don't follow?