A method,
system,
computer program product, and method of doing business by providing a secure integrated device (such as a pervasive computing device) for which operating capabilities can be dynamically yet securely selected (including, but not limited to, pluggable connection of input / output devices and / or application processors that provide selected functions). Each input / output (I / O) device and
application processor to be used is plugged in to a
bus of a security core, and authenticates itself to the security core using
public key infrastructure techniques, thereby creating a secure multi-function device. All of the multi-function device's input and output interactions with its environment necessarily
traverse an I / O
bus under the sole control of the security core. The only communication path between an
application processor and the external environment (such as an I / O device) is through an
application processor bus, which is likewise under control of the security core. Thus a user may dynamically yet securely select the capabilities of a multi-function device, and because each I / O device and application processor in use by that multi-function device is authenticated, the security of transactions or network services performed when using such devices is improved.