Structure-Preserving Signatures on Equivalence Classes and Constant-Size Anonymous Credentials

Fuchsbauer, Georg; Hanser, Christian; Slamanig, Daniel

doi:10.1007/s00145-018-9281-4

Cited by 66 publications

(108 citation statements)

References 80 publications

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“…It uses an equivalence class signature (EQS) scheme, a public-key encryption (PKE) scheme, a hash function (modeled as a random oracle) with images living in G 2 , and a verifiable ring signature (VRS) scheme. We suggest to instantiate our construction with the EQS scheme of Fuchsbauer, Hanser, and Slamanig [20], the PKE scheme obtained by applying the Fujisaki-Okamoto transformation [21] to the ElGamal encryption scheme [? ], and the VRS scheme of Bultel and Lafourcade [9].…”

Section: Our Resultsmentioning

confidence: 99%

Efficient Invisible and Unlinkable Sanitizable Signatures

Bultel

Lafourcade

Lai

et al. 2019

Public-Key Cryptography – PKC 2019

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Sanitizable signatures allow designated parties (the sanitizers) to apply arbitrary modifications to some restricted parts of signed messages. A secure scheme should not only be unforgeable, but also protect privacy and hold both the signer and the sanitizer accountable. Two important security properties that are seemingly difficult to achieve simultaneously and efficiently are invisibility and unlinkability. While invisibility ensures that the admissible modifications are hidden from external parties, unlinkability says that sanitized signatures cannot be linked to their sources. Achieving both properties simultaneously is crucial for applications where sensitive personal data is signed with respect to data-dependent admissible modifications. The existence of an efficient construction achieving both properties was recently posed as an open question by Camenisch et al. (PKC'17). In this work, we propose a solution to this problem with a two-step construction. First, we construct (non-accountable) invisible and unlinkable sanitizable signatures from signatures on equivalence classes and other basic primitives. Second, we put forth a generic transformation using verifiable ring signatures to turn any non-accountable sanitizable signature into an accountable one while preserving all other properties. When instantiating in the generic group and random oracle model, the efficiency of our construction is comparable to that of prior constructions, while providing stronger security guarantees.

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Section: Our Resultsmentioning

confidence: 99%

Efficient Invisible and Unlinkable Sanitizable Signatures

Bultel

Lafourcade

Lai

et al. 2019

Public-Key Cryptography – PKC 2019

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“…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]. The only known security proof for the latter scheme is in the generic group model.…”

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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“…Recently, Hanser and Slamanig [33] (then revised by Fuchsbauer et al [29]) proposed the first credential system where the communication complexity for credential showing is independent of the number of its attributes. Unfortunately, their scheme only supports conjunctive statements and thus lacks expressiveness.…”

Section: Related Workmentioning

confidence: 99%

Functional Credentials

Deuber

Maffei

Malavolta

et al. 2018

Proceedings on Privacy Enhancing Technologies

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Abstract:A functional credential allows a user to anonymously prove possession of a set of attributes that fulfills a certain policy. The policies are arbitrary polynomially computable predicates that are evaluated over arbitrary attributes. The key feature of this primitive is the delegation of verification to third parties, called designated verifiers. The delegation protects the privacy of the policy: A designated verifier can verify that a user satisfies a certain policy without learning anything about the policy itself. We illustrate the usefulness of this property in different applications, including outsourced databases with access control. We present a new framework to construct functional credentials that does not require (non-interactive) zero-knowledge proofs. This is important in settings where the statements are complex and thus the resulting zero-knowledge proofs are not efficient. Our construction is based on any predicate encryption scheme and the security relies on standard assumptions. A complexity analysis and an experimental evaluation confirm the practicality of our approach.

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Structure-Preserving Signatures on Equivalence Classes and Constant-Size Anonymous Credentials

Cited by 66 publications

References 80 publications

Efficient Invisible and Unlinkable Sanitizable Signatures

Efficient Invisible and Unlinkable Sanitizable Signatures

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

Functional Credentials

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