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Eagle Cash

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Re: Eagle Cash

#21

Post by sargun »

louwhopley wrote: post #7
max_ wrote: post #2

Interesting. How does this thing solve the "double spend problem" [0]. Without needing network access? You usually need server communication in electronics payment systems to confirm payment & update account balances. How does Eagle Cash solve this problem? [0]: https://www.investopedia.com/terms/d/doublespending.asp

Similar to many Mastercard/Visa cards. The electronic chip on the card is capable of actually storing the balance and then syncing it back when it reaches a terminal machine that’s connected to the internet. In my experience, many (most) chip-card based transport systems for busses or trains (eg tap n go) operates in this offline mode where it only syncs when you go to the kiosk to top it up. It uses cryptographic me…

How do you solve the FLP problem?

e.g.

Kiosk->Device: Give me $100

Device: Subtract $100 from myself

Device->Kiosk: Send $100 (fail)

Alternatively, what if this happens the other direction?

Re: Eagle Cash

#22

Post by chipsa »

sneak wrote: post #3

> This method allows soldiers to purchase goods and services at U.S. military posts and canteens, without carrying cash, or manage their personal bank accounts while on deployment or in training. The program reduces the amount of American currency required overseas, reduces theft, saves thousands of man-hours in labor, helps reduce the risk of transporting cash in combat environments, and increases security and conve…

It's possible to still use cash on deployed bases. But this reduces the need to use cash for things like: buying from random morale things, like the Fox at the 'Deid.

Re: Eagle Cash

#23

Post by lucb1e »

eecc wrote: post #19
max_ wrote: post #9

Earlier quoted context omitted.

So security is maintained using violence? Not technology?

What do you think society is all about? I can recommend Debt by the late David Graeber

Not sure a whole book is needed, it seems fairly straightforward to show that society is based on threats of violence.

If you don't pay someone, that someone can go to a judge. If you indeed did something illegal (e.g. if you did a double spend, money forgery, whatever) you should be declared guilty and ordered to pay the damages plus perhaps a fine. If you don't do that, the amount due will increase and eventually you get ordered to jail. If you don't go voluntarily, they will make you. Of course everything comes down to force and eventually violence in the end. Why else would you comply with things that don't please you? (Because you're an honest party, okay, and the vast majority of people are, but not everyone is in the privileged position where they have what they want without applying dishonesty.)

Even if you think to solve it with technology, preventing a crime is indeed better than detecting and punishing one, but let's say it's impossible to detect the double spend ahead of time and your technological solution only finds out that there was a double spend after the fact. What's it going to do, block your card from now on? In the end, it will still have real world consequences for you. Taking away someone's card, through physical or technological means, it's all more or less the same thing.

Re: Eagle Cash

#24

Post by zapdrive »

With upcoming satellite internet projects (see Starlink), I think it will be highly unlikely to disconnect any army base totally from the internet. In such scenarios, any centralized service would be much more efficient, secure and convenient. Soldiers can also use cryptocurrencies for trade among themselves, without needing to carry cash.

Re: Eagle Cash

#25

Post by pram »

Huh. I was in the Air Force from 2005-2010 and I literally never saw this. I was at LSA Anaconda in Iraq too (mentioned in the article) ... must be an Army thing?

Re: Eagle Cash

#26

Post by wyattpeak »

sargun wrote: post #21
louwhopley wrote: post #7

Earlier quoted context omitted.

Similar to many Mastercard/Visa cards. The electronic chip on the card is capable of actually storing the balance and then syncing it back when it reaches a terminal machine that’s connected to the internet. In my experience, many (most) chip-card based transport systems for busses or trains (eg tap n go) operates in this offline mode where it only syncs when you go to the kiosk to top it up. It uses cryptographic me…

How do you solve the FLP problem? e.g. Kiosk->Device: Give me $100 Device: Subtract $100 from myself Device->Kiosk: Send $100 (fail) Alternatively, what if this happens the other direction?

Atomic transactions, as with any database. After sending the money, confirm that it arrived. If it didn't, undo the subtraction.

That said, shoddy implementations of these systems often do fail in numerous ways. As an end-user, you really just have to live with it.

Re: Eagle Cash

#27

Post by xedeon »

pram wrote: post #25

Huh. I was in the Air Force from 2005-2010 and I literally never saw this. I was at LSA Anaconda in Iraq too (mentioned in the article) ... must be an Army thing?

It was used in the Air Force as well. It was issued in Basic Training and deployed locations.

https://www.dvidshub.net/image/44435/eagle-cash-has-landed-a...

https://www.af.mil/News/Photos/igphoto/2000452297/

https://www.afcent.af.mil/Units/332nd-Air-Expeditionary-Wing...

Re: Eagle Cash

#28

Post by lmz »

sargun wrote: post #21
louwhopley wrote: post #7

Earlier quoted context omitted.

Similar to many Mastercard/Visa cards. The electronic chip on the card is capable of actually storing the balance and then syncing it back when it reaches a terminal machine that’s connected to the internet. In my experience, many (most) chip-card based transport systems for busses or trains (eg tap n go) operates in this offline mode where it only syncs when you go to the kiosk to top it up. It uses cryptographic me…

How do you solve the FLP problem? e.g. Kiosk->Device: Give me $100 Device: Subtract $100 from myself Device->Kiosk: Send $100 (fail) Alternatively, what if this happens the other direction?

Those cards typically store the last few transactions (e.g. [0] is an Android app that can display transit card usage history), so it should be possible to code idempotency into the card firmware.

[0]: https://play.google.com/store/apps/details?id=com.codebutler...

Re: Eagle Cash

#29

Post by max_ »

lucb1e wrote: post #23
eecc wrote: post #19

Earlier quoted context omitted.

What do you think society is all about? I can recommend Debt by the late David Graeber

Not sure a whole book is needed, it seems fairly straightforward to show that society is based on threats of violence. If you don't pay someone, that someone can go to a judge. If you indeed did something illegal (e.g. if you did a double spend, money forgery, whatever) you should be declared guilty and ordered to pay the damages plus perhaps a fine. If you don't do that, the amount due will increase and eventually y…

One reason I am interested in Bitcoin is that it doesn't rely on violence to enforce it's rules.

Re: Eagle Cash

#30

Post by sargun »

wyattpeak wrote: post #26
sargun wrote: post #21

Earlier quoted context omitted.

How do you solve the FLP problem? e.g. Kiosk->Device: Give me $100 Device: Subtract $100 from myself Device->Kiosk: Send $100 (fail) Alternatively, what if this happens the other direction?

Atomic transactions, as with any database. After sending the money, confirm that it arrived. If it didn't, undo the subtraction. That said, shoddy implementations of these systems often do fail in numerous ways. As an end-user, you really just have to live with it.

What protocol guarantees that there is an atomic transaction, in the presence of faults, in such a system?
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