What is possible with identity based cryptography for PKIs and what still must be improved

This paper is a survey of the advantages that the use of identity based cryptosystems can provide to PKIs. Since its introduction by Shamir in 1984, a couple of breakthroughs have been achieved in this area: namely, several identity based encryption (IBE) and identity based signature (IBS) schemes were proposed as well as hierarchical extensions of these while various special purpose identity based signatures also appeared. Interestingly, this kind of public key encryption and digital signature schemes can easily be turned into other kinds of primitives such as key evolving cryptosystems. This paper summarizes all the interesting properties of ID-based cryptography and recalls the aspects for which it still has to be improved.