How can I officially prove that a Bitcoin private key is owned by an entity?

I am the co-founder of an early-stage startup that aims to prove existence of various qualifications (academic, professional...) via the Bitcoin Blockchain.

In order to validate a piece of data, an issuer (say a university or other issuing body) would have to send a small transaction from their wallet which is managed by us.

Is there any way to officially prove (in this case in UK legislation) that a specific legal entity is in possession of a bitcoin private key and, therefore, to the coins associated with it? I know of a "statutory declaration" but is there anything more specific I can do?

Basically I would like to transfer ownership of the wallet to the customer, in order for myself to be criminally punishable if I upload qualifications to the Blockchain without their consent.

Is this at all possible?

Thanks!

Alberto Deca

Posted 2017-02-07T17:24:34.680

Reputation: 23

Answers

A middle man trying to create a business around being a middle man with a technology thats supposed to remove intermediaries?

It seems like you could accomplish what you want with multisig wallet and counterparty.

In the example I have in mind,

The issuer could create an asset that represents qualifications. The issuer could invite their practitioners to a 2-of-2 multisig address and send the asset to that address.

Although we can't confirm if only those two parties have the keys, we can see where the asset came from (but it one scenario it can also be issued by the multisig address and never moved). We can rest assured that it would require both parties, one of which being the individual, to create a proposal to move the qualification asset. And these proposals will be rejected.

Another perk is that the asset can correspond to a centralized system.

Predictable, there's no place for your business in this mix, but that's probably the point, so I would like to thank you and your investors, in advance, for their charity in bringing this idea to the world. Should probably do an ICO

CQM

Posted 2017-02-07T17:24:34.680

Reputation: 1 472

Thanks for your suggestion. I regret to inform you that the idea of using blockchain technologies to certify the existence and validity of documents is one of the oldest around. Check out "BlockCerts" (blockcerts.org) and "Proof of Existence". – Alberto Deca – 2017-02-08T19:28:30.160

@AlbertoDeca and counterparty, and Factom, other metalayers. Your monetization won't be inherent to the technology, but you could sell a service as long as nobody figures out how simple it is. – CQM – 2017-02-08T22:17:01.303

The whole point of digital signatures is that ownership of the private key is never shared. The owner of a key pair can only prove that he is in control of the private key, but there is no way of proving that nobody else has a copy of the private key. Of course, if someone creates a key pair and signs and publishes a message to the effect that he is the sole owner of that key pair, he'd have a hard time arguing that another message signed using that key was not signed by himself. Your description sounds a bit vague, it is unclear to me what you mean by creating a wallet - do you mean the software (in which case the user would indeed be the owner of the keys) or the wallet data? In the latter case, you cannot prove that you don't keep a copy of the private keys.

Hans-Martin Mosner

Posted 2017-02-07T17:24:34.680

Reputation: 514

I would create a wallet using the software. Then the private key would be in my possession. I'd like to transfer possession of that private key to the customer, but this would make it hard, as you and the other responder say, for them to prove that somebody else sent a tx instead. I would not have an answer to this dilemma... – Alberto Deca – 2017-02-08T19:42:12.100

The only valid solution is to let them create a key and never share the private half with anybody (including you.) – Hans-Martin Mosner – 2017-02-09T14:58:20.783