AutoCrypt Digital Key is a custom development solution based on the CCC Digital Key 3.0 standard with backward compatibility to Release 2.0. The system uses a certificate-chain-of-trust authentication system for vehicle-to-device communications. The solution employs a PKI-based security system that issues certificates at the module manufacturing stage. AutoCrypt Digital Key utilizes Near Field Communication (NFC) technology and can be installed on smartphones with embedded NFC capabilities. The system enables remote vehicle access and control including door and trunk locks, ignition, and horn functions through a smartphone interface. The digital key can be shared with multiple users through shared credentials or invite links. Vehicle owners can configure access restrictions including duration limits, permission settings, and maximum speed controls for shared users. The solution provides components for establishing digital key infrastructure including management server and user application.