## Verifiably Encrypted Signatures: Security Revisited and a New Construction

Authors

Christian Hanser (IAIK, Graz University of Technology), Max Rabkin (CISPA, Saarland University and International Max Planck Research School for Computer Science) and Dominique Schröder (CISPA, Saarland University)

Abstract

In structure-preserving signatures on equivalence classes (SPS-EQ-$\mathcal{R}$), introduced from Asiacrypt 2014, each message $M$ in $(\mathbb{G}^*)^\ell$ is associated to its projective equivalence class, and a signature commits to the equivalence class: anybody can transfer the signature to a new, scaled, representative.In this work, we give the first black-box construction of a public-key encryption scheme from any SPS-EQ-$\mathcal{R}$ satisfying a simple new property which we call perfect composition. The construction does not involve any non-black-box technique and the implication is that such SPS-EQR cannot be constructed from one-way functions in a black-box way. The main idea of our scheme is to build a verifiable encrypted signature (VES) first and then apply the general transformation suggested by Calderon et al. (CT-RSA 2014). The original definition of VES requires that the underlying signature scheme be correct and secure in addition to other security properties. The latter have been extended in subsequent literature, but the former requirements have sometimes been neglected, leaving a hole in the security notion. We show that Calderon et al.'s notion of resolution independence fills this gap.

Venue

20th European Symposium on Research in Computer Security, Computer Security - ESORICS 2015  (http://esorics2015.sba-research.org/)

Place and Date

Vienna, Austria, September 21-25, 2015.

Publication Reference

Christian Hanser, Max Rabkin and Dominique Schröder, "Verifiably Encrypted Signatures: Security Revisited and a New Construction." 20th European Symposium on Research in Computer Security, Computer Security - ESORICS 2015, volume XXXX of LNCS, Springer-Verlag, Vienna, Austria, September 21-25, 2015.

Bibtex

@inproceedings{hanser_es_2015,
Author    = {Christian Hanser and
Max Rabkin and
Dominique Schr{\"o}der},
Title     = {{Verifiably Encrypted Signatures: Security Revisited and New Construction}},
Booktitle = {Computer Security - {ESORICS} 2015 - 20th European Symposium on Research in Computer Security, Vienna, Austria,September 21-25, 2015. Proceedings.},
Year      = {2015},
Publisher                = {Springer},
Series                   = {LNCS},
Volume                   = {XXXX}
}