A portable storage device contains a real time clock, an onboard power source and secure storage. These components enable the device to securely store data and control access thereto. A secret key can be maintained in secure storage, such that access to the device can be denied to external systems that do not have a matching key. A log detailing connections can also be maintained in secure storage, such that device activity can be accurately documented, and made available in a trusted manner to a management system. Furthermore, the onboard real time clock allows stored data to be encrypted and decrypted in conjunction with specified time periods, such that a session key is destroyed after a time out, or is not made available until a given period of time has transpired.