5 ms·

That's exactly it, it's very possible, but all the eggs would be in one basket. Scheme: multiple copies of symmetric key followed by symmetrically encrypted b

That's exactly it, it's very possible, but all the eggs would be in one basket. Scheme: multiple copies of symmetric key followed by symmetrically encrypted body (pgp-style). One copy of the symmetric key is secured by user's private key, another is wrapped in an onion of all required "side" keys. The issue is that the government-held keys only need to be exposed once, and then someone has a key to all of everything, everywhere.

slg 6y ago
They mentioned having multiple keys with different government organizations. What if there are 12 keys and you need 6 keys to decrypt the data. The user has 6 keys. The company that created the device or service has 2 keys, the judicial branch has 2 keys, and the executive branch has 2 keys. All of the non-user keys are required to be in different systems. The compromise of any one system still requires cooperation from the non-user groups to decrypt. You couple that with some system that allows the data to be decrypted and reencrypted with new keys in the case of a breech of keys. You can add as many keys to this scenario as you want until you feel like a breech of the necessary number of keys is not going to happen. Are we sure a system along these lines is impossible?
- dwheeler 6y ago
  Unfortunately, each key will be poorly protected, because each group will rationalize that "it would be impossible for someone to get all those keys" while someone gets all the keys. The US government couldn't even keep the most sensitive information about its personnel secret, see the OPM breach: https://en.wikipedia.org/wiki/Office_of_Personnel_Management_data_breach https://en.wikipedia.org/wiki/Office_of_Personnel_Management... The Inspector General had warned Congress of "persistent deficiencies in OPM's information system security program" and nothing was done. This resulted in some really sensitive data being exfiltrated, probably some good blackmail info. The US government has not done a great job even protecting its own employees. The biggest problem here, though, is incentives. A government cannot be sued, or suffer any other negative impact, if it accidentally loses keys that lead to others' death, blackmail, or job loss. Too bad, so sad. If tomorrow it becomes illegal or unacceptable to do something that today is legal, a government can retroactively punish those who engaged in it. In short, the government has no strong incentive to protect the keys, only you do.
  - slg 6y ago
    It sounds like we have already moved from this is an impossible request to this is a difficult and impractical request. Setting up a government competition with a prize to solve a hard problem seems reasonable.
    - unionpivo 6y ago
      > It sounds like we have already moved from this is an impossible request to this is a difficult and impractical request. I am not sure how you got this from conversation above. Still sounds impossible to me. Problem as stated is, that if skeleton keys are broken, then everything everywhere gets broken. The fact that government has bad initiatives to keep keys secret, just means it will be easier for bad actors to steal them. But that is just a side argument.
      - slg 6y ago
        >I am not sure how you got this from conversation above. Still sounds impossible to me. When discussing encryption, many people say that this is an impossible problem to solve because of math. This conversation has shifted to being a problem about incentives. Math is impossible to change. Incentives are changeable. If the only problems here are the specifics of the scheme and the incentives of people involved, those are solvable. >Problem as stated is, that if skeleton keys are broken, then everything everywhere gets broken. Which is why you build redundancy into the system that would require multiple independent breaches and a system to reencrypt data in the event of a breach.
        nytgop77 6y ago
        Attacker can record encrypted data before getting the masterkey. During usage, all pieces of master key will have to be brought together into one place (phisical or virtual), so eventually still only one breach is needed. If I encypt data using encryption without backdoor, then to illegitimately get clear text requires effort X, and it gives access to 1 persons data. If whole country encrypts data using backdoored scheme, then effort Y will give access to data of 100 000 000 people. It would seem that security of the backdoor should be 100mil times stronger then that of usual crypto.
- tzs 6y ago
  It would be interesting to take something like that to an extreme. Have approximately every adult in the country receive a key share, with 90% of the shares required to reconstruct the key.
  - suizi 6y ago
    Computer viruses.
suizi 6y ago
Modern security involves generating a key for every session and this could be dicey with a master key.
- free_rms 6y ago
  Yeah, that's the symmetric key in this scheme, I should have said session key.

slg 6y ago

They mentioned having multiple keys with different government organizations. What if there are 12 keys and you need 6 keys to decrypt the data. The user has 6 keys. The company that created the device or service has 2 keys, the judicial branch has 2 keys, and the executive branch has 2 keys. All of the non-user keys are required to be in different systems. The compromise of any one system still requires cooperation from the non-user groups to decrypt. You couple that with some system that allows the data to be decrypted and reencrypted with new keys in the case of a breech of keys. You can add as many keys to this scenario as you want until you feel like a breech of the necessary number of keys is not going to happen. Are we sure a system along these lines is impossible?

dwheeler 6y ago
Unfortunately, each key will be poorly protected, because each group will rationalize that "it would be impossible for someone to get all those keys" while someone gets all the keys. The US government couldn't even keep the most sensitive information about its personnel secret, see the OPM breach: https://en.wikipedia.org/wiki/Office_of_Personnel_Management_data_breach https://en.wikipedia.org/wiki/Office_of_Personnel_Management... The Inspector General had warned Congress of "persistent deficiencies in OPM's information system security program" and nothing was done. This resulted in some really sensitive data being exfiltrated, probably some good blackmail info. The US government has not done a great job even protecting its own employees. The biggest problem here, though, is incentives. A government cannot be sued, or suffer any other negative impact, if it accidentally loses keys that lead to others' death, blackmail, or job loss. Too bad, so sad. If tomorrow it becomes illegal or unacceptable to do something that today is legal, a government can retroactively punish those who engaged in it. In short, the government has no strong incentive to protect the keys, only you do.
- slg 6y ago
  It sounds like we have already moved from this is an impossible request to this is a difficult and impractical request. Setting up a government competition with a prize to solve a hard problem seems reasonable.
  - unionpivo 6y ago
    > It sounds like we have already moved from this is an impossible request to this is a difficult and impractical request. I am not sure how you got this from conversation above. Still sounds impossible to me. Problem as stated is, that if skeleton keys are broken, then everything everywhere gets broken. The fact that government has bad initiatives to keep keys secret, just means it will be easier for bad actors to steal them. But that is just a side argument.
    - slg 6y ago
      >I am not sure how you got this from conversation above. Still sounds impossible to me. When discussing encryption, many people say that this is an impossible problem to solve because of math. This conversation has shifted to being a problem about incentives. Math is impossible to change. Incentives are changeable. If the only problems here are the specifics of the scheme and the incentives of people involved, those are solvable. >Problem as stated is, that if skeleton keys are broken, then everything everywhere gets broken. Which is why you build redundancy into the system that would require multiple independent breaches and a system to reencrypt data in the event of a breach.
      - nytgop77 6y ago
        Attacker can record encrypted data before getting the masterkey. During usage, all pieces of master key will have to be brought together into one place (phisical or virtual), so eventually still only one breach is needed. If I encypt data using encryption without backdoor, then to illegitimately get clear text requires effort X, and it gives access to 1 persons data. If whole country encrypts data using backdoored scheme, then effort Y will give access to data of 100 000 000 people. It would seem that security of the backdoor should be 100mil times stronger then that of usual crypto.
tzs 6y ago
It would be interesting to take something like that to an extreme. Have approximately every adult in the country receive a key share, with 90% of the shares required to reconstruct the key.
- suizi 6y ago
  Computer viruses.

suizi 6y ago

Modern security involves generating a key for every session and this could be dicey with a master key.

free_rms 6y ago
Yeah, that's the symmetric key in this scheme, I should have said session key.