In general in a communications security system (and wireless is not an exception), one first of all needs a good crypto engine (also known in some circles as crypto logic) for the actual encryption and decryption. This can be based on block ciphers or stream ciphers.

For the integrity of traffic one would also expect a strong hashing function (as the presence of a simple MAC code is becoming rather antiquated as a standalone technique).

One should then add to the list a system that generates good-quality keys, distributes keys, and verifies keys.

One that allows the optional generation and verification of digital signatures with appropriate hooks to an overlying public-key infrastructure (PKI) entailing certificate authorities (CAs).

Random number generation is essential for good cryptography. Most systems use a pseudo- random number generator (RNG) and people can fool themselves into believing they are secure. From the sampling of RNGs one can generate random bits; hence, the notion of cryptographically strong pseudo-random bit generators (PRBGs) that was pioneered by Blum, Blum, and Shub,24 and Yao.25 The former, also known as the BBS PRBG scheme is also well presented in Schneier.26 Informally, we can say that a PRBG is cryptographically strong if it passes all polynomial-time statistical tests, or in other words, if the distribution of sequence outputs by the generator cannot be distinguished from truly random sequences by any polynomial-time judge.27 A PRBG is...