Efficient enhanced keyword search for encrypted document in cloud

A sensitive public-key searchable encryption system in the prime-order groups, which lets keyword search policies to be uttered in conjunctive, disjunctive or any monotonic Boolean formulas and realizes momentous act enhancement over existing schemes. We legally express its sanctuary, and verify that it is selectively sheltered in the standard model. Correspondingly, we instrument the wished-for outline using a hasty prototyping tool so-called Charm and conduct more than a few experiments to estimate it show. The results determine that our scheme is plentiful more proficient than the ones assembled over the composite-order groups. Keyword research is one of the most imperative, valuable, and high return activities in the search marketing field. Position for the right keywords can make or interruption your website

Cheon\u27s algorithm, pairing inversion and the discrete logarithm problem

We relate the fixed argument pairing inversion problems (FAPI) and the discrete logarithm problem on an elliptic curve. This is done using the reduction from the DLP to the Diffie-Hellman problem developed by Boneh, Lipton, Maurer and Wolf. This approach fails when only one of the FAPI problems can be solved. In this case we use Cheon\u27s algorithm to get a reduction

A Leakage-Abuse Attack Against Multi-User Searchable Encryption

Searchable Encryption (SE) allows a user to upload data to the cloud and to search it in a remote fashion while preserving the privacy of both the data and the queries. Recent research results describe attacks on SE schemes using the access pattern, denoting the ids of documents matching search queries, which most SE schemes reveal during query processing. However SE schemes usually leak more than just the access pattern, and this extra leakage can lead to attacks (much) more harmful than the ones using basic access pattern leakage only. We remark that in the special case of Multi-User Searchable Encryption (MUSE), where many users upload and search data in a cloud-based infrastructure, a large number of existing solutions have a common leakage in addition to the well-studied access pattern leakage. We show that this seemingly small extra leakage allows a very simple yet powerful attack, and that the privacy degree of the affected schemes have been overestimated. We also show that this new vulnerability affects existing software. Finally we formalize the newly identified leakage profile and show how it relates to previously defined ones

Ciphertext-Policy Attribute-Based Broadcast Encryption with Small Keys

Broadcasting is a very efficient way to securely transmit information to a large set of geographically scattered receivers, and in practice, it is often the case that these receivers can be grouped in sets sharing common characteristics (or attributes). We describe in this paper an efficient ciphertext-policy attribute-based broadcast encryption scheme (CP-ABBE) supporting negative attributes and able to handle access policies in conjunctive normal form (CNF). Essentially, our scheme is a combination of the Boneh-Gentry-Waters broadcast encryption and of the Lewko-Sahai-Waters revocation schemes; the former is used to express attribute-based access policies while the latter is dedicated to the revocation of individual receivers. Our scheme is the first one that involves a public key and private keys having a size that is independent of the number of receivers registered in the system. Its selective security is proven with respect to the Generalized Diffie-Hellman Exponent (GDHE) problem on bilinear groups

Computing Optimal Ate Pairings on Elliptic Curves with Embedding Degree 9,159,15 and 2727

Much attention has been given to efficient computation of pairings on elliptic curves with even embedding degree since the advent of pairing-based cryptography. The existing few works in the case of odd embedding degrees require some improvements. This paper considers the computation of optimal ate pairings on elliptic curves of embedding degrees k=9, 15 \mbox{ and } 27 which have twists of order three. Mainly, we provide a detailed arithmetic and cost estimation of operations in the tower extensions field of the corresponding extension fields. A good selection of parameters enables us to improve the theoretical cost for the Miller step and the final exponentiation using the lattice-based method comparatively to the previous few works that exist in these cases. In particular for $k=15$ and $k=27$ we obtained an improvement, in terms of operations in the base field, of up to $25\%$ and $29\%$ respectively in the computation of the final exponentiation. Also, we obtained that elliptic curves with embedding degree $k=15$ present faster results than BN$12$ curves at the $128$-bit security levels. We provided a MAGMA implementation in each case to ensure the correctness of the formulas used in this work

Secure and Scalable Multi-User Searchable Encryption

By allowing a large number of users to behave as readers or writers, Multi-User Searchable Encryption (MUSE) raises new security and performance challenges beyond the typical requirements of Symmetric Searchable Encryption (SSE). In this paper we identify two core mandatory requirements of MUSE protocols being privacy in face of users colluding with the CSP and low complexity for the users, pointing that no existing MUSE protocol satisfies these two requirements at the same time. We then come up with the first MUSE protocol that satisfies both of them. The design of the protocol also includes new constructions for a secure variant of Bloom Filters (BFs) and multi-query Oblivious Transfer (OT)

Optimal Ate Pairing on Elliptic Curves with Embedding Degree 9,159,15 and 2727

Much attention has been given to the efficient computation of pairings on elliptic curves with even embedding degree since the advent of pairing-based cryptography. The few existing works in the case of odd embedding degrees require some improvements. This paper considers the computation of optimal ate pairings on elliptic curves of embedding degrees $k=9$, $15$, $27$ which have twists of order three. Our main goal is to provide a detailed arithmetic and cost estimation of operations in the tower extensions field of the corresponding extension fields. A good selection of parameters enables us to improve the theoretical cost for the Miller step and the final exponentiation using the lattice-based method as compared to the previous few works that exist in these cases. In particular, for $k=15$, $k=27$, we obtain an improvement, in terms of operations in the base field, of up to 25% and 29% respectively in the computation of the final exponentiation. We also find that elliptic curves with embedding degree $k=15$ present faster results than BN12 curves at the 128-bit security level. We provide a MAGMA implementation in each case to ensure the correctness of the formulas used in this work.Comment: 25 page

SoK: Privacy-Preserving Signatures

Modern security systems depend fundamentally on the ability of users to authenticate their communications to other parties in a network. Unfortunately, cryptographic authentication can substantially undermine the privacy of users. One possible solution to this problem is to use privacy-preserving cryptographic authentication. These protocols allow users to authenticate their communications without revealing their identity to the verifier. In the non-interactive setting, the most common protocols include blind, ring, and group signatures, each of which has been the subject of enormous research in the security and cryptography literature. These primitives are now being deployed at scale in major applications, including Intel\u27s SGX software attestation framework. The depth of the research literature and the prospect of large-scale deployment motivate us to systematize our understanding of the research in this area. This work provides an overview of these techniques, focusing on applications and efficiency