In this paper, the authors present a Java Card applet offering the same functionality as a widely used contactless storage card. The goal is to provide a solution for secure and widely deployable data storage for smart phones. The applet provides an independent storage space for different applications with their own keys and configuration and is fully compatible with the MIFARE DESfire card EV1 technology. It can be installed in every Java Card 2.2.1 compatible smart card. Integration with Google Android phones is possible using a secure micro-SD card or other secure platforms that feature a JavaCard chip and a NFC antenna. The DESfire emulator can be accessed both externally through NFC, and internally through the smart phone OS.