Cryptology ePrint Archive: Report 2016/615

Reusing Tamper-Proof Hardware in UC-Secure Protocols

Jeremias Mechler and Jörn Müller-Quade and Tobias Nilges

Abstract: Universally composable protocols provide security even in highly complex environments like the Internet. Without setup assumptions, however, UC-secure realizations of cryptographic tasks are impossible. Tamper-proof hardware tokens, e.g. smart cards and USB tokens, can be used for this purpose. Apart from the fact that they are widely available, they are also cheap to manufacture and well understood.

Currently considered protocols, however, suffer from two major drawbacks that impede their practical realization:

- The functionality of the tokens is protocol-specific, i.e. each protocol requires a token functionality tailored to its need. - Different protocols cannot reuse the same token even if they require the same functionality from the token, because this would render the protocols insecure in current models of tamper-proof hardware.

In this paper we address these problems. First and foremost, we propose formalizations of tamper-proof hardware as an untrusted and global setup assumption. Modeling the token as a global setup naturally allows to reuse the tokens for arbitrary protocols. Concerning a versatile token functionality we choose a simple signature functionality, i.e. the tokens can be instantiated with currently available signature cards. Based on this we present solutions for a large class of cryptographic tasks.

Category / Keywords: universal composability, tamper-proof hardware, unique signatures, global setup

Original Publication (with major differences): IACR-PKC-2018

Date: received 13 Jun 2016, last revised 14 Jun 2018

Contact author: jeremias mechler at kit edu

Available format(s): PDF | BibTeX Citation

Note: Full version of the PKC 2018 publication.

Version: 20180614:083625 (All versions of this report)

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