Key2Share is a system that allows smartphones to be used for access control via Near Field Communication (NFC). It issues digital keys that are represented as QR codes and can be shared remotely. This provides flexible access control with options for easy key delegation, remote revocation of access, and management of access rights. A proof of concept has been developed with Bosch Security Systems to integrate Key2Share into their existing access control infrastructure. The system aims to provide secure access control via smartphones while balancing security and compatibility with mobile devices.