Rethinking Privacy for Extended Sanitizable Signatures and a Black-Box Construction of Strongly Private Schemes

Abstract. Sanitizable signatures, introduced by Ateniese et al. at ESORICS’05, allow to issue a signature on a message where certain predefined message blocks may later be changed (sanitized) by some dedicated party (the sanitizer) without invalidating the original signature. With sanitizable signatures, replacements for modifiable (admissible) message blocks can be chosen arbitrarily by the sanitizer. However, in various scenarios this makes sanitizers too powerful. To reduce the sanitizers power, Klonowski and Lauks at ICISC’06 proposed (among others) an extension that enables the signer to limit the allowed modifications per admissible block to a well defined set each. At CT-RSA’10 Canard and Jambert then extended the formal model of Brzuska et al. from PKC’09 to additionally include the aforementioned and other extensions. We, however, observe that the privacy guarantees of their model do not capture privacy in the sense of the original definition of sanitizable signat...

• Type: Journal
• Year: 2015
• Where: PROVSEC
• Authors: David Derler, Daniel Slamanig
• Keywords: PROVSEC 2015, Security Privacy