The new cards are currently being tested in South Africa, and MasterCard hopes to roll them out to the rest of the world by the end of 2017.
An encrypted digital template of your fingerprint is stored on the card’s EMV chip.
After your templates are saved, your card is ready to be used at compatible terminals worldwide — merchants don’t have to get new equipment to accept your fingerprint-enabled plastic.
The card itself is surprisingly no thicker than a regular credit card. The fingerprint sensor is a small, thumbnail-sized rectangle that sits at the top right corner, and is easily accessible when you stick the card into a payment terminal.
When the terminal asks you to insert the card, it’s communicating to the bank information like your identity and the amount of the transaction. Then, it verifies your identity by asking for your fingerprint. The sensor reads your finger, and sends the information to the card’s chip, which determines if you’re the owner. If you are, it sends a “Yes” or “Authorized” message to the bank, which then allows the payment to pass.
https://www.engadget.com/2017/04/20/mastercard-biometric-fingerprint-card/