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 (SPS-EQ) 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 non-interactive 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.Category / Keywords: public-key cryptography / (Partially) Blind Signatures, Standard Model, SPS-EQ, One-Show Anonymous Credentials Original Publication (with major differences): IACR-CRYPTO-2015 Date: received 23 Jun 2015, last revised 26 Jun 2015 Contact author: georg fuchsbauer at ist ac at Available format(s): PDF | BibTeX Citation Version: 20150630:184252 (All versions of this report) Short URL: ia.cr/2015/626 Discussion forum: Show discussion | Start new discussion