‘Use One Coin for All of Your Cards’

You’ve likely heard about Coin (that’s an affiliate link), a new credit card / iPhone pairing that seeks to eliminate you having to carry multiple cards. It even has its own Sandwich video. The product itself looks fantastic, and easy to use too.

And, as surprising as this might be, I pre-ordered one.

If you read this site you are likely to be surprised by that statement because I am a pretty privacy conscious guy. Before I talk about my thoughts on the security of this system, I want to share some non-security — more practical — concerns that I have with this card.

You Can Change Cards Easily

The first thing I thought when I watched the video was: that’s way to easy to change cards. The Coin shows that, with a push of a button, you can toggle between cards. This is great for the user when they are the one in possession of the Coin, but what about when you hand the card to someone else? Sure if you don’t lose sight of the card you can be sure they haven’t changed your card, but what about at a restaurant?

I’m not even assuming anything malicious — just heavy handed use of the Coin seems like it could cycle between cards and potentially net you with a personal charge on a business card.

I really hope this concern is unfounded, and that there is a mechanism in place to prevent accidental changing of your card, but I remain skeptical.

This is all that is said about this concern on the FAQ:

We’ve designed the button to toggle cards in a way that makes it difficult to trigger a “press” unintentionally. Dropping a Coin, holding a Coin, sitting on a Coin, or putting the Coin in a check presenter at a restaurant will not inadvertently toggle the card that is selected.

That doesn’t instill confidence of any kind in me.

What’s That?

That’s the question I expect to get when I try to use the card. Maybe you won’t get that in San Francisco, but I know I will get asked that. No matter what I say, I suspect that the cashier will assume something shady is going on.

I can imagine a couple conversations that might prevent me from using the card:

  1. “Sir, you can’t use this because we only accept American Express, Visa, and Mastercard. This is neither.” “No, it is an AMEX, trust me.” “Sir, this doesn’t look like any AMEX I have seen. Where’s the logo?” “Ugh.”
  2. “Ummm, I need the three numbers from the back of the card.” “Sure they are right here (points).” “No, I need the ones on the back of the card, there is nothing on the back of this card.” “Ugh.”

I think people are likely to be the biggest usability obstacles.


The Coin FAQ has an entire section on security, but it’s not all that reassuring. There are some features of the Coin that makes it a lot better than a normal card:

  • Push notification if you leave the Coin behind.
  • Card disables if it is out of contact from your phone for too long.

There are two primary security concerns that I see with this product:

  1. That you have to give a lot of credit card info to Coin and it is then stored (from the sound of it) on thier servers. Now, they will be in compliance with required security standards, but how can we trust them? I don’t know, but I don’t see this aspect as any more risky than storing, or using, a credit card with any other company on the web. Be that Amazon, or this site.1

    This is why I don’t see Coin being a big issue — it just doesn’t strike me as any bigger security risk than using your card anywhere else. In addition to that, credit card companies are actually very good at fraud prevention and removing fraudulent charges. I wouldn’t link a debit card to the Coin — and I don’t ever use a debit card as I don’t want people to have that direct of access to my cash — but I don’t see any reason to not use a credit card with it.

  2. I think the next major concern is not with the security of you using a Coin, but with others having access to this technology. In other words, Coin sounds like a credit card skimmers dream tool. I have no doubt this presents a security risk, but why should that stop you from using the Coin, or any other new technology for that matter. All new technology has inherent security risks that are only figured out through wide usage.

    Already waiters have been known to skim credit cards — and the rule of thumb is to not let your card out of your site — but uhh… really?

    Coin, for their part, says specifically on this topic:

    The Coin app requires that you take a picture of the front and back of the card, type in card details, and then swipe the card (using a reader we provide) to ensure the card’s encoded magnetic stripe data matches the card details provided. It is not possible to complete these steps unless you are in physical possession of a card. As an additional safeguard, the Coin app will only allow you to add cards you own.

Everything but that last line is moot. My assumption is that I am out to dinner and hand my card over for payment — now the skimmer has physical possession of my card. If that’s the case, what the hell does the last line of that answer mean? How do they verify ownership? Zip codes?

My best guess is that if your card is already registered with a Coin account, it then cannot be registered with another Coin account. And if that is the case you are probably more secure owning a Coin then you would be if you didn’t own a Coin.

That’s the main flaws I see with the card. The benefit, though, seems to outweigh the risks associated with using the Coin.

If I could truly just carry around a Coin and my ID — well that would be fantastic.

  1. For the record I can’t see your full card number — not even if I tried. I verified that with my own account before launching the paywall. 

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Article Details

by Ben Brooks
5 minutes to read.


You’ve likely heard about Coin (that’s an affiliate link), a new credit card / iPhone pairing that seeks to eliminate you having to carry multiple cards. It even has its own Sandwich video. The product itself looks fantastic, and easy to use too. And, as surprising as this might be, I pre-ordered one. If you […]