You can prove ownership of a private key by signing a challenger-generated nonce with the public part and giving the signature back to the challenger - same as with any asymmetric crypto system. As I already noted, the payment protocol is designed to solve that problem. You could design a BIP that extended the payment protocol to include information about the person who generated it. On Tue, Sep 17, 2013 at 11:30 AM, Wendell wrote: > Couple of things I just thought about: > > 1- Presume server should only sweep with two (or more, see below) > revocation certificates being present > 2- Need to insert something in the flow so that Alice can verify that the > uploaded key is actually Bob's (and perhaps vise-versa, given an extremely > dedicated attacker with a fast connection?). > > Is there a way to do #2 without creating yet another transaction? > Admittedly I am still really puzzled about the accessibility of public keys > in Bitcoin! > > Please remember that the idea is to have two wallets securely exchange a > packet of metadata about a transaction beyond the scope of Bitcoin itself > (a name, perhaps a small photo, etc) in order to increase usability. This > will be my last post here on the topic except to reply in case anyone else > contributes. > > -wendell > > grabhive.com | twitter.com/grabhive | gpg: 6C0C9411 > > On Sep 16, 2013, at 4:05 PM, Wendell wrote: > > > Luke pointed out that we should not be inserting extraneous data into > the blockchain, so this sounds like the best option, Eric. > > > > I'm under the impression that a Bitcoin user Alice cannot see the actual > public key of Bitcoin user Bob, so if we had Hive store metadata on a > server relating to a given transaction ID, I would not be able to use those > public keys key to encrypt. Is this a misunderstanding or is it correct? > > > > Assuming it is correct, the best that I could come up with was storing > the transaction ID with a _fresh_ public key on a server, each time a > transfer is made. Altogether it looks like this: > > > > - Alice generates a new keypair & revocation certificate for the > transaction > > - Alice makes a Bitcoin transaction to Bob > > - Alice sends the transaction ID plus the new public key to server > > - Bob receives the Bitcoin transaction > > - Bob generates a new keypair & revocation certificate > > - Bob does a transaction ID lookup on the server, receives Alice's > public key, sends his own new one > > - Bob encrypts his user metadata against Alice's new key > > - Alice downloads and decrypts Bob's metadata > > - Alice uploads her revocation certificate > > - Alice uploads her own metadata > > - Bob downloads Alice's metadata > > - Bob uploads his revocation certificate > > - (Server removes all keys with revocation certificates) > > > > I presume going the extra mile to generate new keys for each transaction > is helpful for privacy? > > > > The above seems rather inelegant to me. I really don't like that clients > (wallets) are going to be beating down the server all the time checking for > keys, or that there is a possibility of a desynchronization so severe that > the user receives the data much too late for it to be useful. But, I > suppose it can work. > > > > Another thing I'm considering is Alice/Bob validating each other. I > suppose we should include some kind of code that we encourage people to > read to each other over the phone or some other medium, to ensure that "it > really is Alice", before (for example) returning money to a very > legit-looking personage. > > > > Any other thoughts? I would love to do this without using any servers at > all ("serverless keyserver", anyone?), but I am not quite sure how. > > > > -wendell > > > > grabhive.com | twitter.com/grabhive | gpg: 6C0C9411 > > > > On Sep 7, 2013, at 12:47 AM, Eric Lombrozo wrote: > > > >> Why not just use the transaction hash itself for the lookup? Also, > presumably you'd want to encrypt the data so that only the recipient of the > transaction can do this lookup. > >> > >> -Eric > >> > >> On Sep 6, 2013, at 8:07 AM, Wendell wrote: > >> > >>> Hi all, > >>> > >>> We're thinking about ways of automatically exchanging contact details > between wallets, in order to encourage the proliferation of identifiable > names and photos rather than long and hard-to-verify addresses. > >>> > >>> The simplest version goes like this: > >>> > >>> 2 BTC Bitcoin is sent to someone, and a data lookup hash is inserted > into the transaction. When it arrives on the other end, it is indeed looked > up, and instead of being presented with a dialogue that says "you received > 2 BTC from 13Y94z43Nbbb6wevRyk82CeDoYQ5S28zmA", it's "You received 2 BTC > from Frank Jones" including a nice photo. > >>> > >>> Now. We can simply delete this data in reference to the transaction ID > after it happens (or delete it after a time), but is there any more > decentralized way to do it? I would prefer us to run no dedicated servers > that would ever put us in a position of being coerced into giving data, or > otherwise altering our system to store it. > >>> > >>> Any thoughts about this? > >>> > >>> -wendell > >>> > >>> grabhive.com | twitter.com/grabhive | gpg: 6C0C9411 > >>> > >>> > ------------------------------------------------------------------------------ > >>> Learn the latest--Visual Studio 2012, SharePoint 2013, SQL 2012, more! > >>> Discover the easy way to master current and previous Microsoft > technologies > >>> and advance your career. Get an incredible 1,500+ hours of step-by-step > >>> tutorial videos with LearnDevNow. 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