A short redactable signature scheme using pairing

Abstract

Redactable signature schemes permit deletion of arbitrary substrings of a signed document while preserving the authenticity of the remaining document. Most of known redactable signatures based on pairing have large-sized signatures and the sizes depend on the product of security parameter and the number of blocks of the redacted document. In this paper, we present a short redactable signature scheme based on pairing. We modify Waters signature scheme to obtain an underlying standard signature defined on composite-order bilinear group. The modified scheme satisfies the unforgeability under the known message attack based on the Computational Diffie-Hellman assumption. Based on the modified Waters signature, we propose a short redactable signature that is existentially unforgeable under random message attack and weakly private. The size of the proposed scheme is 20% of known redactable signatures using aggregated pairing-based signatures when half of the message blocks are deleted. © 2011 John Wiley & Sons, Ltd.