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Show HN: Kong – Physical Cryptocurrency

kong.cash

311–320 of 395 posts

Re: Show HN: Kong – Physical Cryptocurrency

#311
post #245

Earlier quoted context omitted.

I'm not sure what your point is. The comment I was responding to claimed that verification represented a regression in usability in relation to cash. This is not true, because cash also requires verification. I'm not claiming Kong is better in this regard, simply that it is equivalent.

Not all verification is equally costly.

True, but you should be able to verify a Kong note via an app on your phone pretty easily.

Re: Show HN: Kong – Physical Cryptocurrency

#312
post #255

Earlier quoted context omitted.

> How often have you had any real-life issues with counterfeit money? How often has anyone you know? How often have you even heard of it happening, relative to how often you see and hear of cash being used? A sibling comment provided a source that said that only 1% of 1% of cash is counterfeit. Stores have issues with it all the time. That's why they don't often take large bills. I and my personal acquaintances don't…

1% of 1% (so .01%). Is refusing large bills an effective countermeasure? If so, then yeah — not really an issue. Our economy somehow grinds along just fine. > Sure, the physical objects are made by someone. But the digital tokens to which they refer are produced algorithmically, and the digital tokens are the source of truth here. In what sense? The whole idea here is that I can exchange a physical note to transact w…

> 1% of 1% (so .01%). Is refusing large bills an effective countermeasure? If so, then yeah — not really an issue. Our economy somehow grinds along just fine.

So refuse large Kong notes. Why would you assume the economy finds workarounds for cash but not this?

> In what sense? The whole idea here is that I can exchange a physical note to transact with someone.

Ya, and for most transactions you will. If you're suspicious, you can validate the physical devices using your phone. But for simple transactions with a moderate level of trust, you can accept cash. The same way you accept a $20 from a friend without buying a counterfeit detector pen to check it.

Re: Show HN: Kong – Physical Cryptocurrency

#313

Earlier quoted context omitted.

Is this not strictly worse than cash, then? It’s still a centralized physical currency, but instead of a government with checks and balances that is ostensibly accountable to its citizens, Kong is controlled by an opaque organization accountable to nobody. After reading the paper, I’m still not exactly sure how the lockdrop works. Could you elaborate on it? As for verifying transactions offline, I’m skeptical of how…

> but instead of a government with checks and balances that is ostensibly accountable to its citizens what government is this and can I vote my face onto their currency?

Government with what? Hahaha!

Re: Show HN: Kong – Physical Cryptocurrency

#314
post #310

Earlier quoted context omitted.

Cash doesn't really require verification in most cases, if it looks good its probably good, your possession of the notes is almost certainly enough. You're not really looking for anything other than an obvious counterfeit note. Whereas Kong requires verification because literally anything could have happened to the note that you can't determine through mere visual inspection (all the things I noted). That forces you…

> Cash doesn't really require verification in most cases, if it looks good its probably good, your possession of the notes is almost certainly enough. You're not really looking for anything other than an obvious counterfeit note. Neither would Kong in most cases. Why would you assume that counterfeiting will be anymore common with Kong than it would for cash? > Whereas Kong requires verification because literally any…

> Neither would Kong in most cases. Why would you assume that counterfeiting will be anymore common with Kong than it would for cash?

No, I assume that the risk of a counterfeit bill is much much lower than the risk of the IC on a kong bill failing taking the value of the bill with it forever. There's so many more failure modes for a Kong bill than the plastic it's embedded in.

The bills themselves, aside from being counterfeit, cannot fail. Kong bills can be counterfeit too, and also have tens of new failure modes.

Re: Show HN: Kong – Physical Cryptocurrency

#315

Hi folks, I’m one of the contributors at Kong — https://kong.cash/ . Kong is a physical cryptocurrency that looks, feels and works like traditional cash. You can think of it as an ultra-secure, time locked cryptocurrency wallet with a fixed face value — no one can access the token except for the holder of the note after a period of several years. It consists of a secure element and NFC chips mounted on a flexible PCB…

A user accepting these "verifies" them by assuming that two properties hold if they connect over NFC or via pogo pins to the "gold elements", send a challenge over this connection, and receive in response the challenge signed with a public key associated with locked Kong tokens.

1. the relevant private key is known to only a Kong note's secure element. this is (hopefully) enforced by the secure element's, uh, security, and by the issuer.

2. the relevant private key is known to the secure element on the specific physical Kong note the user has been given.

2 is unenforced in your current design, from what I can see. A crafted note can relay all communication to the secure element of another note (e.g. over low-power RF from a single-use battery or small ultracapacitor).

better, a "dead" Kong note which performs no NFC communication can be given to a merchant; then, a high-power NFC transceiver can be used to pretend to be the note wirelessly (from a handful of meters away, but in a lot of situations that's more than enough). Of course, this one only works if the verifier is using NFC, but... This one is particularly nasty because it's relatively straightforwards to "weaponise" - imagine buying a "kit" off AliExpress which contains fifty dead notes, a ProxMark, and an amplified antenna. Then, in any situation where you're close enough to the person who'll be verifying your notes... just give them a dead one and relay communications. Verification passes, but what the merchant ends up putting in their cash drawer is worthless.

Re: Show HN: Kong – Physical Cryptocurrency

#316

Earlier quoted context omitted.

Cash doesn't really require verification in most cases, if it looks good its probably good, your possession of the notes is almost certainly enough. You're not really looking for anything other than an obvious counterfeit note. Whereas Kong requires verification because literally anything could have happened to the note that you can't determine through mere visual inspection (all the things I noted). That forces you…

>>You're not really looking for anything other than an obvious counterfeit note. That's not because non-obvious counterfeits are not possible. It's just that not many of them are generated. The same could apply to non-obviously sabotaged Kong: theoretically it's possible to do, but in practice uncommon. Kong would have the added benefit of not financially rewarding the sabateur the way counterfeiting rewards a counte…

The risks for a cash bill are just counterfeiting. The risks for a Kong bill are both counterfeiting and failure of the secure element from any of a myriad ways, including thermal, mechanical stress, static, and so on. Those failure modes cannot be detected with the naked eye necessitating much more scrutiny.

It's far more likely your Kong bill just break taking its value with it into the aether than you receiving a counterfeit USD bill.

Re: Show HN: Kong – Physical Cryptocurrency

#317
post #147

Earlier quoted context omitted.

You could make this same criticism of cash, though. It's not a usability regression, they just both have the same flaw. People pass off counterfeit currency as real all the time.

That flaw is mostly a non-issue with cash because printing it is difficult. Who prints Kong? I imagine prevalence of counterfeiting is more or less directly proportional to the ease of printing.

I doubt it is hard to print physical kong notes. They aren't having them printed by Orell Füssli[1] or some other place that prints actual bank notes.

[1] https://www.ofs.ch/products-services/banknotes/

Re: Show HN: Kong – Physical Cryptocurrency

#318
post #312

Earlier quoted context omitted.

1% of 1% (so .01%). Is refusing large bills an effective countermeasure? If so, then yeah — not really an issue. Our economy somehow grinds along just fine. > Sure, the physical objects are made by someone. But the digital tokens to which they refer are produced algorithmically, and the digital tokens are the source of truth here. In what sense? The whole idea here is that I can exchange a physical note to transact w…

> 1% of 1% (so .01%). Is refusing large bills an effective countermeasure? If so, then yeah — not really an issue. Our economy somehow grinds along just fine. So refuse large Kong notes. Why would you assume the economy finds workarounds for cash but not this? > In what sense? The whole idea here is that I can exchange a physical note to transact with someone. Ya, and for most transactions you will. If you're suspici…

> So refuse large Kong notes. Why would you assume the economy finds workarounds for cash but not this?

That makes this, at best not better, and at worst, well, worse, because it introduces a myriad new failure modes.

Re: Show HN: Kong – Physical Cryptocurrency

#319
post #49

I really like the concept of physical electronic cash, but in practice nobody has figured out how to make it work. There are many attacks to consider. The most obvious is to obtain the private key. If you did so, you could give the note to someone else in an environment lacking network access. This would enable double-spending - the main problem Bitcoin solves. The attack can range in complexity from breaking into th…

We have considered both of those attacks and address them in section 2.2 and 3.2 of the white paper respectively[1]. The short version is the key extraction attacks on this specific hardened chip are more expensive than the value they escrow, and in the event a key was extracted it creates a race condition at the period of claim not during the lifetime of its use - still providing some utility. What Kong does that Ca…

> in the event a key was extracted it creates a race condition at the period of claim not during the lifetime of its use - still providing some utility.

So say the key was extracted, you would not be aware until the "maturity" or whatever time you can claim the real value?

How would one then know and trust that the note I'm holding on to won't be claimed by someone else at the period of claim? As far as I see it my best option would be to try and offload any Kong in my possession as soon as possible for real goods or other currency.

Re: Show HN: Kong – Physical Cryptocurrency

#320

Earlier quoted context omitted.

If you're handing off physically then just use cash. How is this any better? The exit to real currency will always reveal Kong transactions at some point. Real cash is more anonymous because it's seamlessly transacted everywhere.

Current cash instruments are centralized.

Somehow I don’t think people buying stuff with dollar bills mind that dollars are “centralised”. In fact I’d venture that this is exactly why dollar bills are accepted in so many places around the world.

Not that Kong isn’t centralised. It’s just that it’s controlled by unknown nobodies, rather than the most powerful entity in the world.

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