Efficient Certificateless Online/Offline Signature

S. Sharmila Deva Selvi¹, S. Sree Vivek¹*, Vivek Krishna Pradhan², and C. Pandu Rangan¹

¹Indian Institute of Technology Madras,

Chennai, Tamil Nadu, India

{sharmila, svivek, prangan}@cse.iitm.ac.in

²Indian Institute of Technology Madras,

Indian Institute of Science Eduction and Research,

Pune, Maharashtra, India

vivek.k.pradhan@gmail.com

Abstract

Public key cryptography usually is computationally more expensive than symmetric key systems.

Due to this low power or resource constrained devices cannot make use of public key cryptosystems

easily. There is a need for high security in these devices since many of these devices perform complex

tasks which includes interaction with third party cloud infrastructures. These cloud infrastructures

are not trusted entities. Hence there is need for light weight public key cryptography which are secure

against these cloud administrators. The trusted entity in certificateless schemes cannot compromise

the security of the users. Online/offline have two parts, first the computationally heavy part(offline)

of the cryptosystem and then the main “online” algorithm for use on resource constrained devices.

The heavy computations are done in the offline phase on a more powerful device.
Hence, Certificateless online/offline schemes are perfect for low power devices interacting with clouds.

In this paper, we present a certificateless online/offline signature scheme. This scheme is the most efficient
certificateless signature scheme in existence and also has the added advantage of being online/offline.
The scheme is proven secure in the random oracle model.

Keywords: certificateless cryptography, online/offline computation, signature, provable security,

random oracle model

*Corresponding author: TCS Lab, BSB 324, Department of Computer Science and Engineering, IIT Madras, Chennai,

India. 600036, Tel: +91-0091-4422575387

Journal of Internet Services and Information Security (JISIS), 2(3/4): 77-92, November 2012 [pdf]