Functional Signcryption

Functional encryption (FE) allows to restrict decryption in a highly sophisticated fashion, whereas, functional signature (FS) enables to enforce arbitrarily complex control on signing capabilities. This paper introduces a new cryptographic primitive, termed as functional signcryption (FSC), which unifies the functionalities of FE and FS into a cost-effective formulation. FSC is a crucial step towards efficient implementation of modern digital communication and storage systems that demand advanced forms of confidentiality and authenticity simultaneously. Precisely, we make the following contributions: