Public Key Cryptography 

About: Public Key Cryptography is an academic conference. The conference publishes majorly in the area(s): Encryption & Public-key cryptography. Over the lifetime, 871 publications have been published by the conference receiving 46671 citations.

Ciphertext-policy attribute-based encryption: an expressive, efficient, and provably secure realization

Abstract: We present a new methodology for realizing Ciphertext-Policy Attribute Encryption (CP-ABE) under concrete and noninteractive cryptographic assumptions in the standard model Our solutions allow any encryptor to specify access control in terms of any access formula over the attributes in the system In our most efficient system, ciphertext size, encryption, and decryption time scales linearly with the complexity of the access formula The only previous work to achieve these parameters was limited to a proof in the generic group model We present three constructions within our framework Our first system is proven selectively secure under a assumption that we call the decisional Parallel Bilinear Diffie-Hellman Exponent (PBDHE) assumption which can be viewed as a generalization of the BDHE assumption Our next two constructions provide performance tradeoffs to achieve provable security respectively under the (weaker) decisional Bilinear-Diffie-Hellman Exponent and decisional Bilinear Diffie-Hellman assumptions

A Generalisation, a Simplification and Some Applications of Paillier's Probabilistic Public-Key System

Abstract: We propose a generalisation of Paillier's probabilistic public key system, in which the expansion factor is reduced and which allows to adjust the block length of the scheme even after the public key has been fixed, without loosing the homomorphic property. We show that the generalisation is as secure as Paillier's original system. We construct a threshold variant of the generalised scheme as well as zero-knowledge protocols to show that a given ciphertext encrypts one of a set of given plaintexts, and protocols to verify multiplicative relations on plaintexts. We then show how these building blocks can be used for applying the scheme to efficient electronic voting.This reduces dramatically the work needed to compute the final result of an election, compared to the previously best known schemes.W e show how the basic scheme for a yes/no vote can be easily adapted to casting a vote for up to t out of L candidates. The same basic building blocks can also be adapted to provide receipt-free elections, under appropriate physical assumptions. The scheme for 1 out of L elections can be optimised such that for a certain range of parameter values, a ballot has size only O(log L) bits.

Threshold Signatures, Multisignatures and Blind Signatures Based on the Gap-Diffie-Hellman-Group Signature Scheme

Abstract: We propose a robust proactive threshold signature scheme, a multisignature scheme and a blind signature scheme which work in any Gap Diffie-Hellman (GDH) group (where the Computational Diffie-Hellman problem is hard but the Decisional Diffie-Hellman problem is easy). Our constructions are based on the recently proposed GDH signature scheme of Boneh et al. [8]. Due to the instrumental structure of GDH groups and of the base scheme, it turns out that most of our constructions are simpler, more efficient and have more useful properties than similar existing constructions. We support all the proposed schemes with proofs under the appropriate computational assumptions, using the corresponding notions of security.

An Identity-Based Signature from Gap Diffie-Hellman Groups

Abstract: In this paper we propose an identity(ID)-based signature scheme using gap Diffie-Hellman (GDH) groups. Our scheme is proved secure against existential forgery on adaptively chosen message and ID attack under the random oracle model. Using GDH groups obtained from bilinear pairings, as a special case of our scheme, we obtain an ID-based signature scheme that shares the same system parameters with the ID-based encryption scheme (BF-IBE) by Boneh and Franklin [BF01], and is as efficient as the BF-IBE. Combining our signature scheme with the BF-IBE yields a complete solution of an ID-based public key system. It can be an alternative for certificate-based public key infrastructures, especially when efficient key management and moderate security are required.

Curve25519: new diffie-hellman speed records

Abstract: This paper explains the design and implementation of a high-security elliptic-curve-Diffie-Hellman function achieving record-setting speeds: e.g., 832457 Pentium III cycles (with several side benefits: free key compression, free key validation, and state-of-the-art timing-attack protection), more than twice as fast as other authors' results at the same conjectured security level (with or without the side benefits).