1. A system comprising: a user speech profile stored on a computer readable storage device, the speech profile containing a plurality of phonemes with user identifying characteristics for the phonemes, wherein the identifying characteristic comprise a representation of the amount of pronunciation difference for each of the plurality of phonemes from an average user; and a speech processor coupled to access the speech profile and generate a phrase containing user distinguishing phonemes based on the pronunciation difference between the user identifying characteristics for such phonemes and average user identifying characteristics, such that the phrase has discriminability from other users wherein the speech processor generates the phrase by searching for a phrase in a library that contains user distinguishing phonemes, wherein a user distinguishing phoneme is based on pronunciation of a phoneme by a user differing from the way most other users pronounce the phoneme and wherein such distinguishing phonemes have an associated score indicative of a magnitude by which such pronunciation differs and wherein the associated score is adjusted based on a difference of the pronunciation from ambient noise, resulting in a different generated phrase in the presence of the ambient noise.