Cryptology ePrint Archive: Report 2018/858

Stronger Security for Sanitizable Signatures

Stephan Krenn and Kai Samelin and Dieter Sommer

Abstract: Sanitizable signature schemes (SSS) enable a designated party (called the sanitizer ) to alter admissible blocks of a signed message. This primitive can be used to remove or alter sensitive data from already signed messages without involvement of the original signer. Current state-of-the-art security definitions of SSSs only de ne a \weak" form of security. Namely, the unforgeability, accountability and transparency definitions are not strong enough to be meaningful in certain use-cases. We identify some of these use-cases, close this gap by introducing stronger definitions, and show how to alter an existing construction to meet our desired security level. Moreover, we clarify a small yet important detail in the state-of-the-art privacy definition. Our work allows to deploy this primitive in more and different scenarios.

Category / Keywords: digital signatures

Original Publication (with minor differences): Data Privacy Management and Security Assurance 2015

Date: received 11 Sep 2018, last revised 3 Nov 2018

Contact author: kaispapers at gmail com

Available format(s): PDF | BibTeX Citation

Note: Fixed a detail in the ENC IND-CPA definition

Version: 20181103:170219 (All versions of this report)

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