Essam Ghadafi's Outputs (18)

Feature vulnerability and robustness assessment against adversarial machine learning attacks (2021)
Presentation / Conference Contribution

Whilst machine learning has been widely adopted for various domains, it is important to consider how such techniques may be susceptible to malicious users through adversarial attacks. Given a trained classifier, a malicious attack may attempt to craf... Read More about Feature vulnerability and robustness assessment against adversarial machine learning attacks.

Partially structure-preserving signatures: Lower bounds, constructions and more (2021)
Presentation / Conference Contribution

In this work we first provide a framework for defining a large subset of pairing-based digital signature schemes which we call Partially Structure-Preserving Signature (PSPS) schemes. PSPS schemes are similar in nature to structure-preserving signatu... Read More about Partially structure-preserving signatures: Lower bounds, constructions and more.

Further lower bounds for structure-preserving signatures in asymmetric bilinear groups (2019)
Presentation / Conference Contribution

Structure-Preserving Signatures (SPSs) are a useful tool for the design of modular cryptographic protocols. Recent series of works have shown that by limiting the message space of those schemes to the set of Diffie-Hellman (DH) pairs, it is possible... Read More about Further lower bounds for structure-preserving signatures in asymmetric bilinear groups.

Towards a classification of non-interactive computational assumptions in cyclic groups (2017)
Presentation / Conference Contribution

We study non-interactive computational intractability assumptions in prime-order cyclic groups. We focus on the broad class of computational assumptions, which we call target assumptions, where the adversary's goal is to compute a concrete group elem... Read More about Towards a classification of non-interactive computational assumptions in cyclic groups.

Linear-time zero-knowledge proofs for arithmetic circuit satisfiability (2017)
Presentation / Conference Contribution

We give computationally efficient zero-knowledge proofs of knowledge for arithmetic circuit satisfiability over a large field. For a circuit with N addition and multiplication gates, the prover only uses O(N) multiplications and the verifier only use... Read More about Linear-time zero-knowledge proofs for arithmetic circuit satisfiability.

More efficient structure-preserving signatures - or: Bypassing the type-III lower bounds (2017)
Presentation / Conference Contribution

© 2017, Springer International Publishing AG. Structure-Preserving Signatures (SPSs) are an important cryptographic primitive that is useful for the design of modular cryptographic protocols. It has be shown that in the most efficient Type-III biline... Read More about More efficient structure-preserving signatures - or: Bypassing the type-III lower bounds.

Foundations of fully dynamic group signatures (2016)
Presentation / Conference Contribution

Group signatures are a central cryptographic primitive that has received a considerable amount of attention from the cryptographic community. They allow members of a group to anonymously sign on behalf of the group. Membership is overseen by a design... Read More about Foundations of fully dynamic group signatures.

Short accountable ring signatures based on DDH (2016)
Presentation / Conference Contribution

Ring signatures and group signatures are prominent cryptographic primitives offering a combination of privacy and authentication. They enable individual users to anonymously sign messages on behalf of a group of users. In ring signatures, the group,... Read More about Short accountable ring signatures based on DDH.

Short structure-preserving signatures (2016)
Presentation / Conference Contribution

© Springer International Publishing Switzerland 2016. We construct a new structure-preserving signature scheme in the efficient Type-III asymmetric bilinear group setting with signatures shorter than all existing schemes. Our signatures consist of 3... Read More about Short structure-preserving signatures.

Efficient Distributed tag-based encryption and its application to group signatures with efficient distributed traceability (2015)
Presentation / Conference Contribution

© Springer International Publishing Switzerland 2015. In this work, we first formalize the notion of dynamic group signatures with distributed traceability, where the capability to trace signatures is distributed among n managers without requiring an... Read More about Efficient Distributed tag-based encryption and its application to group signatures with efficient distributed traceability.

Stronger security notions for decentralized traceable attribute-based signatures and more efficient constructions (2015)
Presentation / Conference Contribution

© Springer International Publishing Switzerland 2015. We revisit the notion of Decentralized Traceable Attribute- Based Signatures (DTABS) introduced by El Kaafarani et al. (CT-RSA 2014) and improve the state-of-the-art in three dimensions: Firstly,... Read More about Stronger security notions for decentralized traceable attribute-based signatures and more efficient constructions.

Attribute-based signatures with user-controlled linkability (2014)
Presentation / Conference Contribution

In this paper, we introduce Attribute-Based Signatures with User-Controlled Linkability (ABS-UCL). Attribute-based signatures allow a signer who has enough credentials/attributes to anonymously sign a message w.r.t. some public policy revealing neith... Read More about Attribute-based signatures with user-controlled linkability.

Decentralized traceable attribute-based signatures (2014)
Presentation / Conference Contribution

We provide a formal security model for traceable attribute-based signatures. Our focus is on the more practical case where attribute management is distributed among different authorities rather than relying on a single central authority. By specializ... Read More about Decentralized traceable attribute-based signatures.

Formalizing group blind signatures and practical constructions without random oracles (2013)
Presentation / Conference Contribution

Group blind signatures combine anonymity properties of both group signatures and blind signatures and offer privacy for both the message to be signed and the signer. The primitive has been introduced with only informal definitions for its required se... Read More about Formalizing group blind signatures and practical constructions without random oracles.

Efficient signatures of knowledge and DAA in the standard model (2013)
Presentation / Conference Contribution

Direct Anonymous Attestation (DAA) is one of the most complex cryptographic protocols deployed in practice. It allows an embedded secure processor known as a Trusted Platform Module (TPM) to attest to the configuration of its host computer without vi... Read More about Efficient signatures of knowledge and DAA in the standard model.

Efficient two-move blind signatures in the common reference string model (2012)
Presentation / Conference Contribution

Blind signatures provide a mechanism for achieving privacy and anonymity whereby a user gets the signer to sign a message of his choice without the signer learning the message, or being able to link a signature to the protocol run via which it was ob... Read More about Efficient two-move blind signatures in the common reference string model.

Groth-Sahai proofs revisited (2010)
Presentation / Conference Contribution

Since their introduction in 2008, the non-interactive zero-knowledge (NIZK) and non-interactive witness indistinguishable (NIWI) proofs designed by Groth and Sahai have been used in numerous applications. In this paper, we offer two contributions to... Read More about Groth-Sahai proofs revisited.

Practical zero-knowledge proofs for circuit evaluation (2009)
Presentation / Conference Contribution

Showing that a circuit is satisfiable without revealing information is a key problem in modern cryptography. The related (and more general) problem of showing that a circuit evaluates to a particular value if executed on the input contained in a publ... Read More about Practical zero-knowledge proofs for circuit evaluation.