Methods and apparatuses for securely operating shared host computers with portable apparatuses

The present invention provides methods and apparatuses that utilize a portable apparatus to securely operate a host electronic device. Typically, each portable apparatus includes a data storage unit which stores an operating system and other software. In one example, a portable apparatus can provide a virtual operating environment on top of a host's operating system for a host device. In another example, a portable apparatus containing its operating system can directly boot a host device with one or more hardware profiles. Furthermore, a device-dependent protection against software piracy, a user-dependent protection against sensitive data leaks, a controllable host operating environment to prevent unwanted information exposure, and a secure restoration procedure to prevent virus infection between the host device users may be incorporated. Moreover, an authorization signature may also be utilized to authorize a connected-state guest operation environment in the host device.