Efficient Construction of Identity Based Signcryption Schemes
from Identity Based Encryption and Signature Schemes

Sumit Kumar Pandey and Rana Barua

Indian Statistical Institute

Kolkata -700108

{sumit_r,rana}@isical.ac.in

Abstract

In this paper, we show how to construct an Identity Based Signcryption Scheme (IBSC) using an

Identity Based Encryption (IBE) and an Identity Based Signature (IBS) schemes. This we obtain by

first extending the An-Dodis-Rabin construction to the Identity Based setting and then instantiating.

We then further modify the construction to obtain an efficient construction. We show that the security

of the IBSC scheme–indistinguishability as well as unforgeablity–is derived from the security of the

underlying IBE and IBS schemes. Moreover, we show that under mild (reasonable) assumptions, the

scheme is both space and time efficient compared to the Sign-then-Encrypt approach.

Keywords: Identity Based Encryption, Identity Based Signature, Identity Based Signcryption