Huge interest in and demand for services over the information superhighway have pressed various telecommunications research fronts and led to a new form of future Internet consisting of wired and wireless segments where resource-constrained devices such as mobile devices, smart phones, palm pilots, and wireless sensors may become integral parts of the Internet rather than access-only platforms. One of the key design problems is the security in such heterogeneous networks, particularly over wireless networks with resource constraints. In this tutorial article we discuss a novel approach to addressing security issues, and articulate why and how ID-based cryptography can be effectively applied to address various security problems in resource-constrained wireless networks.