Practical round-optimal blind signatures in the standard model Conference Paper

Author(s): Fuchsbauer, Georg; Hanser, Christian; Slamanig, Daniel
Title: Practical round-optimal blind signatures in the standard model
Title Series: LNCS
Affiliation IST Austria
Abstract: Round-optimal blind signatures are notoriously hard to construct in the standard model, especially in the malicious-signer model, where blindness must hold under adversarially chosen keys. This is substantiated by several impossibility results. The only construction that can be termed theoretically efficient, by Garg and Gupta (Eurocrypt’14), requires complexity leveraging, inducing an exponential security loss. We present a construction of practically efficient round-optimal blind signatures in the standard model. It is conceptually simple and builds on the recent structure-preserving signatures on equivalence classes (SPSEQ) from Asiacrypt’14. While the traditional notion of blindness follows from standard assumptions, we prove blindness under adversarially chosen keys under an interactive variant of DDH. However, we neither require non-uniform assumptions nor complexity leveraging. We then show how to extend our construction to partially blind signatures and to blind signatures on message vectors, which yield a construction of one-show anonymous credentials à la “anonymous credentials light” (CCS’13) in the standard model. Furthermore, we give the first SPS-EQ construction under noninteractive assumptions and show how SPS-EQ schemes imply conventional structure-preserving signatures, which allows us to apply optimality results for the latter to SPS-EQ.
Keywords: Standard model; (Partially) Blind signatures; SPS-EQ; One-show anonymous credentials
Conference Title: CRYPTO: International Cryptology Conference
Volume: 9216
Conference Dates: August 16 - 20, 2015
Conference Location: Santa Barbara, CA, USA
Publisher: Springer  
Date Published: 2015-08-01
Start Page: 233
End Page: 253
DOI: 10.1007/978-3-662-48000-7_12
Notes: G. Fuchsbauer—Supported by the European Research Council, ERC Starting Grant (259668-PSPC). C. Hanser—Supported by EU FP7 through project MATTHEW (GA No. 610436). C. Hanser, D. Slamanig—Supported by EU FP7 through project FutureID (GA No. 318424).
Open access: yes (repository)
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