Building a Custom Java Card Applet for Payment Cards

Our card runs a custom applet on a JCOP4 (Java Card Open Platform) chip. Here's what that actually means and how we built it. What Is Java Card? Java Card is a technology that allows Java-based applets to run on smart cards and secure elements. It's the platform behind most EMV chip cards, SIM cards, and government ID cards. JCOP (Java Card Open Platform) is NXP's implementation. JCOP4 is the latest generation, supporting: RSA up to 4096 bits ECC including P-256 (secp256r1) AES-25