On the Relation between Redactable and Sanitizable Signature Schemes

Abstract

Abstract. Malleable signature schemes (MSS) enable a third party to alter signed data in a controlled way, maintaining a valid signature after an authorized change. Most well studied cryptographic constructions are (1) redactable signatures (RSS), and (2) sanitizable signatures (SSS). RSSs allow the removal of blocks from a signed document, while SSSs allow changing blocks to arbitrary strings. We rigorously prove that RSSs are less expressive than SSSs: no unforgeable RSS can be transformed into an SSS. For the opposite direction we give a black-box transformation of a single SSS, with tightened security, into an RSS.

Hierarchical Privacy CAs for Cross-Border Transfer of Personal Data

“…The compatibility of regulations related to personal data should be clearly addressed and handled. It is expected that with increasing trust, decentralized multi-cloud environments are about to unlock great potential for future data analysis [4,5,10,11,12].…”

“…For instance, a Japanese act [9] permits the transfer of personal data to the EU while an EU directive [1,3] does not permit the transfer of the data to Japan. Although there have been few technical studies on security and privacy for decentralized multi-cloud environments, these studies have not focused on privacy issues in relation to the cross-border transfer of personal data [6,10]. In order to resolve this problem, Hidano et al designed a security gateway to interpret the regulations in both countries that is capable of flexibly controlling the access permissions of the application while taking privacy into consideration [8].…”