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Comment by elicash | Hacker News Reader

I find the way it's used by credit card companies interesting.

When making a purchase, you can do a different signature each time. You can doodle, draw a straight line, write your name, mix it up, whatever. The only value of the signature is that if you don't recall making a purchase, they can send it to you and it can help trigger your memory or make you trust whether or not the purchase was actually you. So it's not for them to use in the verification process. It's for us to help trigger our memories.

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Originally one point was that you signed the back of your card and the merchant would compare the signature on your receipt to the signature on the card to verify your identity. Another point was so the merchant has proof you intended to pay them.

When I was living in the UK (which wisely uses a more sensible PIN system instead of signatures) I was shocked the first time someone asked to see the back of my card. I don't think it's ever happened to me in the US. Culturally we've collectively decided to ignore the whole "signature verification" thing, but when using your card abroad you sometimes are reminded that it's supposed to happen in theory.

Yeah the problem is you can't really do that with elections. That's what makes them so tricky to do well at a distance (be it electronic voting or mail in though I trust mail in more than anything involving computers) it's hard to go back and fix any issues or audit and maintain anonymity. On top of just the sheer number of votes it's a lot of time and uncertainty to try to go back and forth trying to hash out votes.

That's not why you sign a credit slip. You sign it so the vendor can match it against the signature on the back of the card, because they are on the hook if you later claim fraud. If it matches the back of the card it is a lot harder to claim fraud.

The fact that you can put any doodle you want in there is because the vendors have decided it's cheaper to absorb the fraud than to check the signatures.

Their actions show that signatures aren't actually used in the way you describe. It does say to sign the back of the card, but I've never done so and it's never been checked. Not only do vendors not check, but there's no attempt by credit card companies at getting vendors to check. And they don't check on their end, either. The reason is not just because it's inefficient given the amount of fraud, but also because it's unreliable as a security mechanism.

So clearly, that's not how the signature is actually used. What matters is how it's actually used, which is to help prevent good faith actors from accidentally reporting purchases as fraudulent. That's a valid use, but noteworthy.

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