Abstract

It is well known that excessive computational demands of public key cryptography have made its use limited especially when constrained devices are of concern. To reduce the costs of generating public key signatures one viable method is to employ a third party; the server. In open networks, getting help from a verifiable-server has an advantage over proxy-based solutions since as opposed to proxy-server, verifiable-server’s cheating can be proven.

Verifiable-server assisted signatures were proposed in the past but they could not totally eliminate public key operations for the signer. In this paper, we propose a new alternative called SAOTS (server assisted one-time signatures) where just like proxy signatures generating a public key signature is possible without performing any public key operations at all. This feature results in both computational efficiency and implementation simplicity (e.g. a reduction in the code size) of the proposed protocol. In addition, SAOTS is a more promising approach since the signature is indistinguishable from a standard signature, no storage is necessary for the signer to prove the server’s cheating and the protocol works in less number of rounds (two instead of three). On the other hand, the drawback of SAOTS is the increased bandwidth requirement between the sender and server.

Keywords: Server-assisted signature; One-time signature; Digital signature; Nonrepudiation; Network security

Article Outline

1. Introduction

2. Related work

2.1. Efficient public key signatures without server

2.2. One-time signatures

2.3. Signatures employing a server

2.4. Verifiable-server assisted signatures

2.5. SAS protocol weaknesses

3. The proposed SAOTS protocol

3.1. The basic idea

3.2. Setup

3.3. Operation

4. Security analysis

4.1. Security of underlying components

4.2. Dispute resolution

4.3. Denial of service attacks

5. Performance evaluation

5.1. Computation and communication comparisons of SAS and SAOTS protocols

5.2. How to choose parameters for SAOTS

5.3. Implementation and experiments

5.4. Theoretical comparison of network delays

5.5. How about power efficiency?

6. A size reduction technique: SAOTS with hash chains

7. Revocation of public key certificates

8. Conclusion and future work

Acknowledgements

References

Vitae