3 ms·
> This scheme implies you trust this distributor not to make copies of the key for himself (queue sauron references...). I've wondered if there's a scheme that
by generalizations 4y ago
> This scheme implies you trust this distributor not to make copies of the key for himself (queue sauron references...). I've wondered if there's a scheme that does NOT trust the distributor of the key.
What you describe still trusts the distributor - you just found a way to make the distributor easy to trust. I'd be more interested in a mechanism that is mathematically correct, like some of the papers referenced elsewhere in this thread.
- lrvick 4y agoEven if you avoid trusting the distributor, the quorum of share holders still will end up having to reconstitute the shared key into the memory of a computer somewhere at some point to do cryptographic operations with it. There is no avoiding standing up computers all parties trust and if you are going to do that anyway then you might as well use them for key generation and distribution too.
- generalizations 4y agoWell, now you've just turned your locked box into a key distribution machine, and there's a big difference in the security profile of each.
- lrvick 4y agoWhat is the point of generating a cryptographic key that you can never safely use?
- generalizations 4y agoI mean that the security profile of a simple 'locked box' that only knows the keys when all parties agree to unlock it is a very different from the security profile of a 'key distribution machine' like you described. I mean, if we all agreed to perform the decryption, the secret's out anyway. But not before then.
- lrvick 4y agoDepends on use case I suppose. I can not think of many practical applications for one-time-use keys other than disaster recovery flows. The real world use cases I most commonly support are things like CAs, TLS keys, financial transaction signing keys, and sensitive document decryption keys. All of these require single keys to exist that needs to perform automated operations, and needs to be on systems that can be backed up, restored, upgraded, and maintained, while able to prove no single person can access or control the keys. The scheme I described can allow one key to be created, split, restored, used, and split again many times without full trust in any individual.