Eli5: How is a debit chip or tap to pay anymore secure than a mag strip with the same data on it?
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I haven’t seen anyone here talk about symmetric and asymmetric encryption, which I think is also a pretty important piece of the puzzle.
Asymmetric encryption is the backbone is a lot of modern cryptography. Imagine you have a public key and a private key. The public key, you can give out to everyone. The private key, you keep private. Both of them can be used to encrypt or decrypt messages. The thing is that if a message was encrypted using your public key, ONLY the private key can decrypt it. Likewise, if a message was encrypted using your private key, ONLY the public key can decrypt it.
This can have a lot of benefits. If you encrypt something with your own personal private key, the bank KNOWS it was you, because when they decrypt it using your public key, you are the only one who could have sent that transaction. The reverse of this would be if I wanted to send you a private message, I could encrypt it using your public key, and be confident in the knowledge that you are the only person in the world who could decrypt that message.
In the real world, this technology is used everywhere from bank cards to web browsers. Take a look at the top of your web browser, at the little lock in the URL box. That lock shows that your browser has authenticated the website’s certificate using their public key. Your bank card, and your web browser, are both doing this stuff automagically all the time. Among other things, the most important thing your bank card has on it is a set of public and private keys.
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