Paper 2009/320

Automorphic Signatures in Bilinear Groups and an Application to Round-Optimal Blind Signatures

Georg Fuchsbauer


We introduce the notion of automorphic signatures, which satisfy the following properties: the verification keys lie in the message space, messages and signatures consist of elements of a bilinear group, and verification is done by evaluating a set of pairing-product equations. These signatures make a perfect counterpart to the powerful proof system by Groth and Sahai (Eurocrypt 2008). We provide practical instantiations of automorphic signatures under appropriate assumptions and use them to construct the first efficient round-optimal blind signatures. By combining them with Groth-Sahai proofs, we moreover give practical instantiations of various other cryptographic primitives, such as fully-secure group signatures, non-interactive anonymous credentials and anonymous proxy signatures. To do so, we show how to transform signature schemes whose message space is a group to a scheme that signs arbitrarily many messages at once.

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Public-key cryptography
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Published elsewhere. Unknown where it was published
anonymitydigital signaturesblind signatureselliptic curve cryptosystem
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fuchsbau @ di ens fr
2010-03-17: last of 5 revisions
2009-07-01: received
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      author = {Georg Fuchsbauer},
      title = {Automorphic Signatures in Bilinear Groups and an Application to Round-Optimal Blind Signatures},
      howpublished = {Cryptology ePrint Archive, Paper 2009/320},
      year = {2009},
      note = {\url{}},
      url = {}
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