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What if there was a way to give only the US government access to the data? For example, somehow have a shared encryption scheme where the user holds a decryptio

What if there was a way to give only the US government access to the data? For example, somehow have a shared encryption scheme where the user holds a decryption key to decrypt her data, but the government and the company can somehow use their keys in conjunction to decrypt the data as well. (This means company must be complicit in releasing the data, so they have the opportunity to verify/fight the warrant.) If someone came up with such a secure encryption scheme, would that be a palatable approach? I ask this because I'm curious whether you (and people in general) believe that hackability is the only obstacle to giving government access to personal data (with a warrant, of course), or if people would still be uncomfortable with such a system. Personally, I think such a scheme would be a good compromise, but I'm not a crypto expert so I don't know if it's in any way feasible.

fossuser 11y ago
I think the general opinion from the 'cryptowars' in the 90s is that there is no such scheme that does't cripple the actual security of encryption. Key escrow came up back then though I don't think it included needing multiple keys in order to decrypt - not sure if that's mathematically possible or if there's another reason that never came up. I suppose to the government that's not much different than still needing to compel individuals for the key. Your point about companies is interesting since things like iMessage could be MITM currently anyway to get unencrypted content for government requests. I think most people don't necessarily trust the company behavior here though and given the government's recently revealed behavior with National Security Letters and secret, massive, unwarranted data collection I don't think they should get a pass. I'd rather side on the power structure unable to collect some of the information even if they're unable to investigate. I think fundamentally introducing multiple ways to get keys takes a secure system and makes it insecure - the access no longer rests on one individual's knowledge. In general I think that's a bad idea - it also doesn't prevent people who want to actually encrypt their information from doing so (it just harms the regular public and dumber criminals).
- polymatter 11y ago
  > needing multiple keys in order to decrypt - not sure if that's mathematically possible As a matter of interest Shamirs Secret Sharing algorithm (https://en.wikipedia.org/wiki/Shamir's_Secret_Sharing https://en.wikipedia.org/wiki/Shamir's_Secret_Sharing) is quite nice in that respect. The "secret" would be the decryption key. Using Shamirs Secret Sharing algorithm you could split the key into two so you would need both parts in order to work out the decryption key. The government could have a part. The company could have another. Only when both were combined could anyone work out the decryption key. This would mean neither the company nor the government could decrypt messages until they work together - and therefore reduce the risk of hackers and rogue employees. It wouldn't break the encryption with dangerous backdoors but would allow the authorities to quickly gain access when needed for a specific investigation. I doubt anyone would ever implement anything like that since it would be (slightly more) complex and you would have to trust that the decryption parts are valid. But I thought I would just mention it in case anyone else might find that algorithm as interesting as I do.
  - fossuser 11y ago
    That's a cool algorithm - and while it does reduce the risk of a hack succeeding I think it still could be considered a 'backdoor'. It's just a backdoor that requires to people to work together to open, harder to compromise yes - but I'd argue still not really secure. If you have a government entity routinely breaking into companies and taking over access to things (targeting sysadmins) then the scheme doesn't work very well. I think most of the argument behind encryption falls on this idea that it either is secure (no backdoors) or it isn't. You have a spectrum of insecure things you can do that are arguably better than nothing, but they're not secure.

fossuser 11y ago

I think the general opinion from the 'cryptowars' in the 90s is that there is no such scheme that does't cripple the actual security of encryption. Key escrow came up back then though I don't think it included needing multiple keys in order to decrypt - not sure if that's mathematically possible or if there's another reason that never came up. I suppose to the government that's not much different than still needing to compel individuals for the key. Your point about companies is interesting since things like iMessage could be MITM currently anyway to get unencrypted content for government requests. I think most people don't necessarily trust the company behavior here though and given the government's recently revealed behavior with National Security Letters and secret, massive, unwarranted data collection I don't think they should get a pass. I'd rather side on the power structure unable to collect some of the information even if they're unable to investigate. I think fundamentally introducing multiple ways to get keys takes a secure system and makes it insecure - the access no longer rests on one individual's knowledge. In general I think that's a bad idea - it also doesn't prevent people who want to actually encrypt their information from doing so (it just harms the regular public and dumber criminals).

polymatter 11y ago
> needing multiple keys in order to decrypt - not sure if that's mathematically possible As a matter of interest Shamirs Secret Sharing algorithm (https://en.wikipedia.org/wiki/Shamir's_Secret_Sharing https://en.wikipedia.org/wiki/Shamir's_Secret_Sharing) is quite nice in that respect. The "secret" would be the decryption key. Using Shamirs Secret Sharing algorithm you could split the key into two so you would need both parts in order to work out the decryption key. The government could have a part. The company could have another. Only when both were combined could anyone work out the decryption key. This would mean neither the company nor the government could decrypt messages until they work together - and therefore reduce the risk of hackers and rogue employees. It wouldn't break the encryption with dangerous backdoors but would allow the authorities to quickly gain access when needed for a specific investigation. I doubt anyone would ever implement anything like that since it would be (slightly more) complex and you would have to trust that the decryption parts are valid. But I thought I would just mention it in case anyone else might find that algorithm as interesting as I do.
- fossuser 11y ago
  That's a cool algorithm - and while it does reduce the risk of a hack succeeding I think it still could be considered a 'backdoor'. It's just a backdoor that requires to people to work together to open, harder to compromise yes - but I'd argue still not really secure. If you have a government entity routinely breaking into companies and taking over access to things (targeting sysadmins) then the scheme doesn't work very well. I think most of the argument behind encryption falls on this idea that it either is secure (no backdoors) or it isn't. You have a spectrum of insecure things you can do that are arguably better than nothing, but they're not secure.