Comment by dogma1138 | Hacker News Reader

Comment by dogma1138 | Hacker News Reader

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No one said you can overdraw your account but the terminal would simply refuse to connect or the transaction would be rejected by the server due to clock sync issues. Also no one said that the terminals get a GPS signal either but if the clock is off on them vs the server they will fail, I have worked on a lot of payment systems.

Rackmount atomic clocks still need a GPS signal today to be set or they have to be pre-set in a central location and then distributed.

Time syncing used to be a PITA and now it’s easy due to GPS so pretty much every protocol has a very narrow time tolerance. My work HP laptop drifts 3-5 min over the weekend of the VPN because it’s not set to an external time server and all hell breaks loose.

Yes civilization will not end over night but it would have a major impact we will find ways to get by but there will be havoc and the financial damages will be in the trillions heck the disruption to shipping and logistics alone would be immense nearly every one and every thing today is reliant on GPS either directly or indirectly.

> No one said you can overdraw your account

False: The qz article I'm responding to says this.

"When you pull cash from an ATM or swipe your card at the coffee shop, the machine needs to determine the precise time that the transaction occurs to, for example, prevent it from being over-drawn."

Please please explain how this "over-drawn" situation occurs because of a GPS satellite.

> but if the clock is off on them vs the server they will fail, I have worked on a lot of payment systems.

False, CC terminal clocks do not need to be GPS time accurate. When the terminal connects to authenticate, they can update their time. There can be issues with authentication if clock skew is bad, but this requires normal levels of time sync (ie, NTP without GPS will be fine).

While the reason is not necessarily correct (although it’s more of an over simplification than an outright error) the terminal needs to have the correct time if not the transaction would not be processed for a myriad of reasons.

The issue is that in the vast chain of networks that a single transaction flows through you have multiple NTP servers each of them taking their own time form a different source which is often backed by GPS.

If GPS services are disrupted globally this would cause payment networks to break down.

Yes there would be a way to recover from it and move away from GPS but you are still missing the point on day-0 of a GPS blackout the global financial system would go down and it would be a mess and it wouldn’t be a mess that is easily sorted…

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