Recalling the taxonomy of the wireless communications systems (from a computing needs point of view) from the previous chapter, a quick classification of implementation approaches may be made, based on what needs to be secure:

• Large amounts of traffic to be processed, potentially in a high-speed network, especially when it is transmitted unpredictably in real-time.

  Typical examples are: telephone conversations, video conferencing, streaming audio or encoded video transmissions (video-on-demand for instance), telemetry data, and so forth. One does not usually have the luxury of processing leisurely this type of data in software, potentially executing double passes over the data (as in some compressing algorithms), as the data is coming in at significant line speeds and must be treated in real-time. Hardware resources are not close by, to temporarily swallow the mass of data, and consequently, buffer overflow leads to disaster unless the architecture of the system is such that full processing can be executed before the next incoming piece of data is presented at the input.

• Very small amounts of bit traffic to be processed in a moderately high-speed network, transmitted unpredictably and in real-time.

  Typical examples of this realm are e-commerce or m-commerce transactions, credit card number transmission, choice of a specific item to order, order placement with signature, issuing instructions to one s broker, bank account information extraction, making e-payments, and micro-browser-based (WAP-style) HTML page browsing (which in a handheld wireless device will, of course, be transmitted in lean...