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nvK (OP)
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August 09, 2016, 03:52:41 PM |
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I got it. But how can we check that the private key on this gadget really belongs to the address the balance of which we can check on the blockchain without revealing it? In other words, is it possible to "authenticate" the wallet on the device without "compromising" it? If it is not possible to do without showing the private key, you can't accept it from someone without risking a double-spend or give it to someone else unless you give it "blindly", i.e. without knowing the private key and whether the wallet is authentic. Thereby, you can pass this wallet only once offchain, then you will have to use the blockchain again (at first to check and then to reset the stick)...
There is a whole FAQ on authenticity and validation here https://opendime.com/#faq . It also ships with a few open source validation python scripts for advance users. But better yet, the Electrum plugin will be merged soon and you will be able to do "paranoid" check right from Electrum! I read the FAQ on your page, and this part clearly states that Opendime units are expected to be used only once: We expect most Opendime units to be loaded once, probably with a "round number" of bitcoins, and unloaded exactly once in their lifetime. It's impossible to know what's happened in the meantime—just like a gold coin that has passed through many hands over the years That means that you can't make n-transactions offchain as you at first stated. What did I miss? You can deposit more and pass it along multiple times like a bearer bond if sealed. They can only be unsealed once. I got that, but this is precisely the point I'm trying to clarify. Say, you are given a stick which allegedly has some bitcoins on it (you are told so). Okay, you know the address, and you can check on the blockchain how many bitcoins belong to this address, but you don't know the private key (until you unseal the device), thereby you don't know if the stick does actually contain the wallet with that address (and its private key)... In this way you are required to break the seal to make sure it is authentic (i.e. get the private key), but after that the device is no longer usable Opendime will sign a message using it's private key; can be verified with any wallet |
It's the bitcoin incentive that makes the "blockchain" technology work, stupid.
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Even in the event that an attacker gains more than 50% of the network's
computational power, only transactions sent by the attacker could be
reversed or double-spent. The network would not be destroyed.
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deisik
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August 09, 2016, 04:12:26 PM |
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I got that, but this is precisely the point I'm trying to clarify. Say, you are given a stick which allegedly has some bitcoins on it (you are told so). Okay, you know the address, and you can check on the blockchain how many bitcoins belong to this address, but you don't know the private key (until you unseal the device), thereby you don't know if the stick does actually contain the wallet with that address (and its private key)...
In this way you are required to break the seal to make sure it is authentic (i.e. get the private key), but after that the device is no longer usable
Opendime will sign a message using it's private key; can be verified with any wallet That means that the key is internally readable without unsealing the device, and as such can be read by whoever gets access to it, right? So it would be possible to extract the private key (maybe programmatically) and then try to double spend the coins loaded in the wallet... Take it as a warning, if your device takes off in serious, someone will hack it eventually |
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nvK (OP)
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August 09, 2016, 05:05:25 PM |
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I got that, but this is precisely the point I'm trying to clarify. Say, you are given a stick which allegedly has some bitcoins on it (you are told so). Okay, you know the address, and you can check on the blockchain how many bitcoins belong to this address, but you don't know the private key (until you unseal the device), thereby you don't know if the stick does actually contain the wallet with that address (and its private key)...
In this way you are required to break the seal to make sure it is authentic (i.e. get the private key), but after that the device is no longer usable
Opendime will sign a message using it's private key; can be verified with any wallet That means that the key is internally readable without unsealing the device, and as such can be read by whoever gets access to it, right? So it would be possible to extract the private key (maybe programmatically) and then try to double spend the coins loaded in the wallet... Take it as a warning, if your device takes off in serious, someone will hack it eventually Similar to Trezor or Ledger, to remove the private key you'd need to spend a few hundred thousand dollars to peel open the micro and read with an electron microscope. By it's nature, the private key for Opendime has to reside inside the device. |
It's the bitcoin incentive that makes the "blockchain" technology work, stupid.
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deisik
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August 09, 2016, 05:17:02 PM
Last edit: August 09, 2016, 05:49:18 PM by deisik |
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I got that, but this is precisely the point I'm trying to clarify. Say, you are given a stick which allegedly has some bitcoins on it (you are told so). Okay, you know the address, and you can check on the blockchain how many bitcoins belong to this address, but you don't know the private key (until you unseal the device), thereby you don't know if the stick does actually contain the wallet with that address (and its private key)...
In this way you are required to break the seal to make sure it is authentic (i.e. get the private key), but after that the device is no longer usable
Opendime will sign a message using it's private key; can be verified with any wallet That means that the key is internally readable without unsealing the device, and as such can be read by whoever gets access to it, right? So it would be possible to extract the private key (maybe programmatically) and then try to double spend the coins loaded in the wallet... Take it as a warning, if your device takes off in serious, someone will hack it eventually Similar to Trezor or Ledger, to remove the private key you'd need to spend a few hundred thousand dollars to peel open the micro and reading with an electron microscope. By it's nature, the private key for Opendime has to reside inside the device. Yeah, but they are not intended to change hands, and (I hope) the private keys are encrypted with a passphrase in them (I don't really know). So even an electron microscope won't help a would-be hacker. If you add this feature (as an option), that would make the wallet by far more resistant to a possible hack, and no one will be able to grab your coins if you accidentally lose the stick. In any case, now I understand how the device works. If it can confirm the address with a signed message, you can rest assured that it has the right key and the address of the wallet is indeed authentic... Thanks for sparing your time |
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nvK (OP)
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August 09, 2016, 07:09:37 PM |
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Happy to answer questions  |
It's the bitcoin incentive that makes the "blockchain" technology work, stupid.
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nvK (OP)
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August 16, 2016, 02:11:28 PM |
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It's the bitcoin incentive that makes the "blockchain" technology work, stupid.
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OROBTC
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August 20, 2016, 01:36:03 AM |
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Update on my use of OPENDIME hardware
I bought six of them, tried one out to learn the device within a day or so of arrival. The instructions and device lay-out were "good enough" for me to load the device with random input, later to "load" the wallet with BTC. Later, I broke the small stick (in center with lock logo) to get the private key, and had the small amount of BTC there swept to my blockchain.info wallet. (More detail upthread, this was a summary).
* * *
I have since gone on to load up two more with somewhat larger amounts of BTC with the idea of keeping them as "cold storage" devices (not really recommended by nvK, but they're my devices now, smile). The OPENDIMEs are now ready to be issued as "payment" or as a gift (two of the uses foreseen by their website). YES, there is no way to securely backup the Private Key (it's hidden in my unbroken devices), but they are securely locked away, as one would lock up gold or CA$H.
One nice thing about them is that I will never have to "update firmware", as I have had to do with both Ledger and Trezor. In both cases I was nervous during the update process... But, I was forced to do so with the Trezor, else it would not work (not even open to see amount).
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OROBTC
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August 20, 2016, 03:49:57 AM |
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...
Actually, another question just occurred to me, nvK.
Based on what I read at your website (FAQs), it looks like the OPENDIME does not need to be in any communication with your website (no communication via the Web implies greater security for us users). Doing the deeper security checks is beyond my capability.
Is that correct (no communication of the device with opendime)?
Perhaps readers of this thread may be interested to know that it looks like both Trezor and Ledger both require connection to their sites (not sure, but I believe that is the case).
No firmware updates and no connections back to opendime.com are big positives in my book.
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Dank14
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August 20, 2016, 07:22:18 AM |
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Is it like a paper wallet where anybody that has your private keys can spend it?
If the opendime gets stolen, the thief can spend the coins?
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deisik
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August 20, 2016, 08:26:40 AM
Last edit: August 20, 2016, 11:20:53 AM by deisik |
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Is it like a paper wallet where anybody that has your private keys can spend it?
If the opendime gets stolen, the thief can spend the coins?
Yes, he can. That's why I proposed to use a passphrase (as an option) to encrypt the private key. If this option is implemented, and you make use of it (i.e. encrypt the key), you would have to pass the thingie with a passphrase, for example, written on paper. Yes, that would make using opendimes a bit cumbersome, but in this case there will be less incentive for thieves to steal them. In case you lose one, you won't be as much frustrated (since no one will be able to appropriate your coins)... And the one who finds it will feel like returning it to you for a reward (you could stick your address to it) |
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OROBTC
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August 24, 2016, 05:51:17 AM |
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Interesting proposal, deisik, re a password to protect Opendime.
* * *
But, my question for nvK today would be how an Opendime's balance could be accessed if all wallets in the future become HD wallets.
My (poor) understanding is that HD wallets do not permit importing Private Keys. This may be a problem if there is no way in the future to "sweep" balance from an Opendime to and HD wallet.
How do we move BTC "from" an Opendime to an HD wallet (for that matter, to a Ledge Nano or a Trezor) or other wallets in the future?
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gravitate
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August 24, 2016, 11:55:08 AM |
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This is Perfect!!! is it open source? also do you know the precise deimentions please? How many do you have? I would be interested in 50 but need precise deimentions 1st please |
To peel or not to peel.
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gravitate
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August 24, 2016, 12:08:38 PM |
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Also lets say you put in 10 BTC and it gets lost... there is no back up or way to redeam it right? what if it malfunctions or something. Hmm its interesting but with out a back up I would be pretty worried. But with a back up its pointless. Hmm this is really interesting idea but there must be something as a fail safe. IE. removable memory or something. Is there anything?
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To peel or not to peel.
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deisik
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August 24, 2016, 01:59:03 PM |
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Also lets say you put in 10 BTC and it gets lost... there is no back up or way to redeam it right? what if it malfunctions or something. Hmm its interesting but with out a back up I would be pretty worried. But with a back up its pointless. Hmm this is really interesting idea but there must be something as a fail safe. IE. removable memory or something. Is there anything?
The only safe back-up of sorts that I can come up with is to split your bitcoins between two sticks. On the other hand, this increases the cumulative risk of one device malfunctioning two times, wtf... So it still seems to be six of one and half a dozen of the other |
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gravitate
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August 25, 2016, 12:06:31 PM |
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Also lets say you put in 10 BTC and it gets lost... there is no back up or way to redeam it right? what if it malfunctions or something. Hmm its interesting but with out a back up I would be pretty worried. But with a back up its pointless. Hmm this is really interesting idea but there must be something as a fail safe. IE. removable memory or something. Is there anything?
The only safe back-up of sorts that I can come up with is to split your bitcoins between two sticks. On the other hand, this increases the cumulative risk of one device malfunctioning two times, wtf... So it still seems to be six of one and half a dozen of the other Yeah... It would be good enough for me if there was a tamper proof piece of memory that contained the private key or something. Personally I would feel very not safe putting 10 bitcoin on here. Although its a great concept just this slight bad feeling I got about it. Damn its just Almost perfect Im still gonna buy some. |
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gravitate
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August 25, 2016, 12:09:14 PM |
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maybe they come in a pair of 2 with the same address... You can use either to withdraw the bitcoin...
That would work. It would double the price per transaction but it would be safer and work. So if you ever accept one you have to take 2.
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To peel or not to peel.
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deisik
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August 25, 2016, 12:11:08 PM |
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Also lets say you put in 10 BTC and it gets lost... there is no back up or way to redeam it right? what if it malfunctions or something. Hmm its interesting but with out a back up I would be pretty worried. But with a back up its pointless. Hmm this is really interesting idea but there must be something as a fail safe. IE. removable memory or something. Is there anything?
The only safe back-up of sorts that I can come up with is to split your bitcoins between two sticks. On the other hand, this increases the cumulative risk of one device malfunctioning two times, wtf... So it still seems to be six of one and half a dozen of the other Yeah... It would be good enough for me if there was a tamper proof piece of memory that contained the private key or something. Personally I would feel very not safe putting 10 bitcoin on here. Although its a great concept just this slight bad feeling I got about it. Damn its just Almost perfect Im still gonna buy some. As the rep has said, opendimes are not intended for keeping coins. Their primary purpose is to give (sell or gift) bitcoins to a person without making an actual transaction on the blockchain... So if you don't trust these devices with 10 bitcoins (I wouldn't either), use the plain old blockchain |
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deisik
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August 25, 2016, 12:15:50 PM |
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maybe they come in a pair of 2 with the same address... You can use either to withdraw the bitcoin...
That would work. It would double the price per transaction but it would be safer and work. So if you ever accept one you have to take 2.
How would you know that exactly this batch of opendimes is not supplied as triples, to provide for an even better reliability? And you would actually need to take all three of them to avoid a double-spend... Or would it be a triple-spend already? |
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August 25, 2016, 02:33:45 PM |
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maybe they come in a pair of 2 with the same address... You can use either to withdraw the bitcoin...
That would work. It would double the price per transaction but it would be safer and work. So if you ever accept one you have to take 2.
How would you know that exactly this batch of opendimes is not supplied as triples, to provide for an even better reliability? And you would actually need to take all three of them to avoid a double-spend... Or would it be a triple-spend already? lol I know.. I think something like this is a great idea though. I make physical cryptos like Casascius and was always wanting something like this. I suppose for a 1st attempt its awesome. I certainly would put a shrine up in my living room and worship someone who has made this. I just wouldnt use it really I would only keep it as something cool to have. |
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deisik
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September 12, 2016, 09:37:14 AM
Last edit: September 12, 2016, 01:54:47 PM by deisik |
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maybe they come in a pair of 2 with the same address... You can use either to withdraw the bitcoin...
That would work. It would double the price per transaction but it would be safer and work. So if you ever accept one you have to take 2.
How would you know that exactly this batch of opendimes is not supplied as triples, to provide for an even better reliability? And you would actually need to take all three of them to avoid a double-spend... Or would it be a triple-spend already? lol I know.. I think something like this is a great idea though. I make physical cryptos like Casascius and was always wanting something like this. I suppose for a 1st attempt its awesome. I certainly would put a shrine up in my living room and worship someone who has made this. I just wouldnt use it really I would only keep it as something cool to have. Yeah, I was rather skeptical myself about these devices at first, but if they polish this technology of transactionless money transfer in the future and make it as cheap as dirt and as reliable as a Swiss watch (and recyclable at that), then it might get traction as well as widespread recognition and popularity after all... For example, between retail merchants and suppliers |
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