Practical Round-Optimal Blind Signatures in the Standard Model

Fuchsbauer, Georg; Hanser, Christian; Slamanig, Daniel

doi:10.1007/978-3-662-48000-7_12

Cited by 57 publications

(22 citation statements)

References 40 publications

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“…1 to 4) we present the intuition behind it. As a central building block we use an SPS-EQ scheme, which we use in a way that is inspired by their use to construct round-optimal blind signatures in [16], but significantly extended to handle updates. More precisely, the key of the provider represents an SPS-EQ key for vectors of length ℓ = 2 and the commitment parameters (ℎ 1 , .…”

Section: Instantiationmentioning

confidence: 99%

“…Experiment Exp euf-cma A,SPS-EQ ( , ℓ) BG ← Gen(1 ) (sk, pk) ← KeyGen(BG, ℓ) ( * , * ) ← A Sign(sk,•) (pk) return 1 if [ * ] ≠ [ ] ∀ ∈ Q ∧ Vrfy( * , * , pk) = 1. return 0 Figure 9: Unforgeability of SPS-EQ Definition B.4 (Perfect Adaption of Signatures [16]). An SPS-EQ scheme on (G * ) ℓ perfectly adapts signatures if for all tuples (sk, pk, , , ) where it holds that VKey(sk, pk) = 1, Vrfy( , , pk) = 1, ∈ (G * ) ℓ , and ∈ Z * , the distributions ( , Sign( , sk)) and ChgRep( , , , pk) are identical.…”

Section: B1 Sps-eqmentioning

confidence: 99%

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Privacy-Preserving Incentive Systems with Highly Efficient Point-Collection

Bobolz

Eidens

Krenn

et al. 2020

Proceedings of the 15th ACM Asia Conference on Computer and Communications Security

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Incentive systems (such as customer loyalty systems) are omnipresent nowadays and deployed in several areas such as retail, travel, and financial services. Despite the benefits for customers and companies, this involves large amounts of sensitive data being transferred and analyzed. These concerns initiated research on privacy-preserving incentive systems, where users register with a provider and are then able to privately earn and spend incentive points. In this paper we construct an incentive system that improves upon the state-of-the-art in several ways: (1) We improve efficiency of the Earn protocol by replacing costly zero-knowledge proofs with a short structure-preserving signature on equivalence classes. (2) We enable tracing of remainder tokens from double-spending transactions without losing backward unlinkability. (3) We allow for secure recovery of failed Spend protocol runs (where usually, any retries would be counted as double-spending attempts). (4) We guarantee that corrupt users cannot falsely blame other corrupt users for their double-spending. We propose an extended formal model of incentive systems and a concrete instantiation using homomorphic Pedersen commitments, ElGamal encryption, structure-preserving signatures on equivalence classes (SPS-EQ), and zero-knowledge proofs of knowledge. We formally prove our construction secure and present benchmarks showing its practical efficiency.

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Section: Instantiationmentioning

confidence: 99%

Section: B1 Sps-eqmentioning

confidence: 99%

Privacy-Preserving Incentive Systems with Highly Efficient Point-Collection

Bobolz

Eidens

Krenn

et al. 2020

Proceedings of the 15th ACM Asia Conference on Computer and Communications Security

Self Cite

View full text Add to dashboard Cite

show abstract

“…Similarly, the papers [147,146] present efficient blind signature schemes which, the papers' titles promise, are proven secure in the "standard model." However, both blind signature schemes employ the "structure-preserving signature scheme on equivalence classes" from [148].…”

Section: 22mentioning

confidence: 99%

“…The only known security proof for the latter scheme is in the generic group model. Thus, the use of the word "standard" to describe the security assumptions in [147,146] is misleading. This model consists of an encryption oracle and a decryption oracle.…”

Section: 22mentioning

confidence: 99%

Critical perspectives on provable security: Fifteen years of "another look" papers

Koblitz¹,

Menezes²

2019

Advances in Mathematics of Communications

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“…Besides the first attribute-based anonymous credential scheme for which the complexity of showing is independent of the number of attributes [FHS19], ECS have also been used to build very efficient blind signatures with minimal interaction between the signer and the user that asks for the signature [FHS15,FHKS16], revocable anonymous credentials [DHS15], as well as efficient constructions [FGKO17,DS18] of both access-control encryption [DHO16] and dynamic group signatures [BSZ05].…”

Section: Introductionmentioning

confidence: 99%

Efficient Signatures on Randomizable Ciphertexts

Bauer

Fuchsbauer

2020

Lecture Notes in Computer Science

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Randomizable encryption lets anyone randomize a ciphertext so it is distributed like a fresh encryption of the same plaintext. Signatures on randomizable ciphertexts (SoRC), introduced by Blazy et al. (PKC'11), let one adapt a signature on a ciphertext to a randomization of the latter. Since signatures can only be adapted to ciphertexts that encrypt the same message as the signed ciphertext, signatures obliviously authenticate plaintexts. SoRC have been used as a building block in e-voting, blind signatures and (delegatable) anonymous credentials. We observe that SoRC can be seen as signatures on equivalence classes (JoC'19), another primitive with many applications to anonymous authentication, and that SoRC provide better anonymity guarantees. We first strengthen the unforgeability notion for SoRC and then give a scheme that provably achieves it in the generic group model. Signatures in our scheme consist of 4 bilinear-group elements, which is considerably more efficient than prior schemes.

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Practical Round-Optimal Blind Signatures in the Standard Model

Cited by 57 publications

References 40 publications

Privacy-Preserving Incentive Systems with Highly Efficient Point-Collection

Privacy-Preserving Incentive Systems with Highly Efficient Point-Collection

Critical perspectives on provable security: Fifteen years of "another look" papers

Efficient Signatures on Randomizable Ciphertexts

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