Fuchsbauer, GeorgIST Austria; Hanser, Christian; Slamanig, Daniel
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.
233 - 253
CRYPTO: International Cryptology Conference
Santa Barbara, CA, United States
2015-08-16 – 2015-08-20
Fuchsbauer G, Hanser C, Slamanig D. Practical round-optimal blind signatures in the standard model. In: Vol 9216. Springer; 2015:233-253. doi:10.1007/978-3-662-48000-7_12
Fuchsbauer, G., Hanser, C., & Slamanig, D. (2015). Practical round-optimal blind signatures in the standard model (Vol. 9216, pp. 233–253). Presented at the CRYPTO: International Cryptology Conference, Santa Barbara, CA, United States: Springer. https://doi.org/10.1007/978-3-662-48000-7_12
Fuchsbauer, Georg, Christian Hanser, and Daniel Slamanig. “Practical Round-Optimal Blind Signatures in the Standard Model,” 9216:233–53. Springer, 2015. https://doi.org/10.1007/978-3-662-48000-7_12.
G. Fuchsbauer, C. Hanser, and D. Slamanig, “Practical round-optimal blind signatures in the standard model,” presented at the CRYPTO: International Cryptology Conference, Santa Barbara, CA, United States, 2015, vol. 9216, pp. 233–253.
Fuchsbauer G, Hanser C, Slamanig D. 2015. Practical round-optimal blind signatures in the standard model. CRYPTO: International Cryptology Conference, LNCS, vol. 9216. 233–253.
Fuchsbauer, Georg, et al. Practical Round-Optimal Blind Signatures in the Standard Model. Vol. 9216, Springer, 2015, pp. 233–53, doi:10.1007/978-3-662-48000-7_12.
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