Systems, methods, and devices for user authentication using cards with private keys

A method for conducting transactions using cards with keys, comprising:

• receiving, at a merchant host and from a card reading device, a unique identifier for a card, a key read from the card, additional data received by the card reading device during a transaction;
• communicating, by the merchant host, the unique identifier, the key, and the additional data to a backend for a financial institution;
• receiving, by the merchant host and from the backend, authorization for the transaction;
• receiving, by the merchant host and from the backend, an encoded shipping address for the transaction, wherein the backend is configured to encode a shipping address into the encoded shipping address;
• and
• providing, by the merchant host, a product associated with the transaction with the encoded shipping address to a shipping partner;
• wherein the shipping partner of the financial institution is configured to decode the encoded shipping address and deliver the product to the shipping address.

A method for user authentication using cards with keys, comprising:

• receiving, at a backend for a financial institution, a unique identifier for a card, a key read from the card by a card reading device, and additional data received by the card reading device;
• retrieving, by the backend, stored additional data associated with the unique identifier;
• retrieving, by the backend, a stored key associated with the unique identifier in response to the received additional data matching the stored additional data;
• confirming, by the backend, that the received key and the stored key are related;
• and
• providing, by the backend and at a portal, access to a plurality of services.