A novel k-out-of-n Oblivious Transfer Protocols Based on Bilinear Pairings

Low bandwidth consumption is an important issue in a busy commercial network whereas time may not be so crucial, for example, the end-of-day financial settlement for commercial transactions in a day. In this paper, we construct a secure and low bandwidth-consumption k-out-of-n oblivious transfer scheme based on bilinear pairings. We analyze the security and efficiency of our scheme and conclude that our scheme is more secure and efficient in communication bandwidth consumption than most of the other existing oblivious transfer schemes that we know

Attribute Based Pseudonyms : Anonymous and Linkable Scoped Credentials

Attribute-based credentials (ABCs) provide an efficient way to transfer custody of personal and private data to the final user, while minimizing the risk of sensitive data revelation and thus granting anonymity. Nevertheless, this method cannot detect whether one attribute has been used more than once without compromising anonymity when the emitter and consumer collude with one another. The protocol proposed in this article deals with this issue by using a modification of ZSS pairing-based short signatures over elliptic curves and Verheul's self-blinded credentials scheme. Each user can generate an identifier (pseudonym) that is unique and verifiable by everyone in a given scope, without compromising anonymity. However, the identifier cannot be reused in the same scope, since such reuse would be detected

Short structure-preserving signatures

© 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 group elements from the first source group and therefore they are shorter than those of existing schemes as existing ones have at least one component in the second source group whose elements bit size is at least double that of their first group counterparts. Besides enjoying short signatures, our scheme is fully re-randomizable which is a useful property for many applications. Our result also consti- tutes a proof that the impossibility of unilateral structure-preserving signatures in the Type-III setting result of Abe et al. (Crypto 2011) does not apply to constructions in which the message space is dual in both source groups. Besides checking the well-formedness of the message, verifying a signature in our scheme requires checking 2 Pairing Product Equations (PPE) and require the evaluation of only 5 pairings in total which matches the best existing scheme and outperforms many other existing ones. We give some examples of how using our scheme instead of existing ones improves the efficiency of some existing cryptographic pro- tocols such as direct anonymous attestation and group signature related constructions

Privacy-Preserving Electronic Ticket Scheme with Attribute-based Credentials

Electronic tickets (e-tickets) are electronic versions of paper tickets, which enable users to access intended services and improve services' efficiency. However, privacy may be a concern of e-ticket users. In this paper, a privacy-preserving electronic ticket scheme with attribute-based credentials is proposed to protect users' privacy and facilitate ticketing based on a user's attributes. Our proposed scheme makes the following contributions: (1) users can buy different tickets from ticket sellers without releasing their exact attributes; (2) two tickets of the same user cannot be linked; (3) a ticket cannot be transferred to another user; (4) a ticket cannot be double spent; (5) the security of the proposed scheme is formally proven and reduced to well known (q-strong Diffie-Hellman) complexity assumption; (6) the scheme has been implemented and its performance empirically evaluated. To the best of our knowledge, our privacy-preserving attribute-based e-ticket scheme is the first one providing these five features. Application areas of our scheme include event or transport tickets where users must convince ticket sellers that their attributes (e.g. age, profession, location) satisfy the ticket price policies to buy discounted tickets. More generally, our scheme can be used in any system where access to services is only dependent on a user's attributes (or entitlements) but not their identities.Comment: 18pages, 6 figures, 2 table