Cryptology ePrint Archive: Report 2014/908

Practical UC security with a Global Random Oracle

Ran Canetti and Abhishek Jain and Alessandra Scafuro

Abstract: We show that there exist commitment, zero-knowledge and general function evaluation protocols with universally composable security, in a model where all parties and all protocols have access to a single, global, random oracle and no other trusted setup. This model provides significantly stronger composable security guarantees than the traditional random oracle model of Bellare and Rogaway [CCS’93] or even the common reference string model. Indeed, these latter models provide no security guarantees in the presence of arbitrary protocols that use the same random oracle (or reference string or hash function).

Furthermore, our protocols are highly efficient. Specifically, in the interactive setting, our commitment and general computation protocols are much more efficient than the best known ones due to Lindell [Crypto’11,’13] which are secure in the common reference string model. In the non-interactive setting, our protocols are slightly less efficient than the best known ones presented by Afshar et al. [Eurocrypt ’14] but do away with the need to rely on a non-global (programmable) reference string.

Category / Keywords: foundations / Efficient Secure 2PC, UC-security, Global Random Oracle.

Original Publication (with major differences): ACM CCS 2014

Date: received 4 Nov 2014, last revised 16 Nov 2014

Contact author: alescafu at gmail com

Available format(s): PDF | BibTeX Citation

Note: Full version.

Version: 20141116:182219 (All versions of this report)

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