27,117 research outputs found
Approximate Quantum Error-Correcting Codes and Secret Sharing Schemes
It is a standard result in the theory of quantum error-correcting codes that
no code of length n can fix more than n/4 arbitrary errors, regardless of the
dimension of the coding and encoded Hilbert spaces. However, this bound only
applies to codes which recover the message exactly. Naively, one might expect
that correcting errors to very high fidelity would only allow small violations
of this bound. This intuition is incorrect: in this paper we describe quantum
error-correcting codes capable of correcting up to (n-1)/2 arbitrary errors
with fidelity exponentially close to 1, at the price of increasing the size of
the registers (i.e., the coding alphabet). This demonstrates a sharp
distinction between exact and approximate quantum error correction. The codes
have the property that any components reveal no information about the
message, and so they can also be viewed as error-tolerant secret sharing
schemes.
The construction has several interesting implications for cryptography and
quantum information theory. First, it suggests that secret sharing is a better
classical analogue to quantum error correction than is classical error
correction. Second, it highlights an error in a purported proof that verifiable
quantum secret sharing (VQSS) is impossible when the number of cheaters t is
n/4. More generally, the construction illustrates a difference between exact
and approximate requirements in quantum cryptography and (yet again) the
delicacy of security proofs and impossibility results in the quantum model.Comment: 14 pages, no figure
Controlled secure social cloud data sharing based on a novel identity based proxy re-encryption plus scheme
Currently we are witnessing a rapid integration of social networks and cloud computing, especially on storing social media contents on cloud storage due to its cheap management and easy accessing at any time and from any place. However, how to securely store and share social media contents such as pictures/videos among social groups is still a very challenging problem. In this paper, we try to tackle this problem by using a new cryptographic primitive: identity based proxy re-encryption plus (IBPRE ), which is a variant of proxy re-encryption (PRE). In PRE, by using re-encryption keys, a ciphertext computed for Alice can be transferred to a new one for Bob. Recently, the concept of PRE plus (PRE) was introduced by Wang et al. In PRE, all the algorithms are almost the same as traditional PRE, except the re-encryption keys are generated by the encrypter instead of the delegator. The message-level based fine-grained delegation property and the weak non-transferable property can be easily achieved by PRE , while traditional PRE cannot achieve them. Based on the 3-linear map, we first propose a new IBE scheme and a new IBPRE scheme, we prove the security of these schemes and give the properties and performance analysis of the new IBPRE scheme. Finally, we propose a new framework based on this new primitive for secure cloud social data sharingPeer ReviewedPostprint (author's final draft
Interoperability, Trust Based Information Sharing Protocol and Security: Digital Government Key Issues
Improved interoperability between public and private organizations is of key
significance to make digital government newest triumphant. Digital Government
interoperability, information sharing protocol and security are measured the
key issue for achieving a refined stage of digital government. Flawless
interoperability is essential to share the information between diverse and
merely dispersed organisations in several network environments by using
computer based tools. Digital government must ensure security for its
information systems, including computers and networks for providing better
service to the citizens. Governments around the world are increasingly
revolving to information sharing and integration for solving problems in
programs and policy areas. Evils of global worry such as syndrome discovery and
manage, terror campaign, immigration and border control, prohibited drug
trafficking, and more demand information sharing, harmonization and cooperation
amid government agencies within a country and across national borders. A number
of daunting challenges survive to the progress of an efficient information
sharing protocol. A secure and trusted information-sharing protocol is required
to enable users to interact and share information easily and perfectly across
many diverse networks and databases globally.Comment: 20 page
Scooby: Improved Multi-Party Homomorphic Secret Sharing Based on FHE
We present new constructions of multi-party homomorphic secret sharing (HSS) based on a new primitive that we call homomorphic encryption with decryption to shares (HEDS).
Our first construction, which we call Scooby, is based on many popular
fully homomorphic encryption (FHE) schemes with a linear decryption property. Scooby achieves an -party HSS for general circuits with complexity , as opposed to for the prior best construction based on multi-key FHE.
Scooby can be based on (ring)-LWE with a super-polynomial modulus-to-noise ratio. In our second construction, Scrappy, assuming any generic FHE plus HSS for NC1-circuits, we obtain a HEDS scheme which does not require a super-polynomial modulus. While these schemes all require FHE, in another instantiation, Shaggy, we show how in some cases it is possible to obtain multi-party HSS without FHE, for a small number of parties and constant-degree polynomials.
Finally, we show that our Scooby scheme can be adapted to use multi-key fully homomorphic encryption, giving more efficient spooky encryption and setup-free HSS. This latter scheme, Casper, if concretely instantiated with a B/FV-style multi-key FHE scheme, for functions which do not require bootstrapping, gives an HSS complexity of
Distributed Relay Protocol for Probabilistic Information-Theoretic Security in a Randomly-Compromised Network
We introduce a simple, practical approach with probabilistic
information-theoretic security to mitigate one of quantum key distribution's
major limitations: the short maximum transmission distance (~200 km) possible
with present day technology. Our scheme uses classical secret sharing
techniques to allow secure transmission over long distances through a network
containing randomly-distributed compromised nodes. The protocol provides
arbitrarily high confidence in the security of the protocol, with modest
scaling of resource costs with improvement of the security parameter. Although
some types of failure are undetectable, users can take preemptive measures to
make the probability of such failures arbitrarily small.Comment: 12 pages, 2 figures; added proof of verification sub-protocol, minor
correction
An image steganography using improved hyper-chaotic Henon map and fractal Tromino
Steganography is a vital security approach that hides any secret content within ordinary data, such as multimedia. First, the cover image is converted into a wavelet environment using the integer wavelet transform (IWT), which protects the cover images from false mistakes. The grey wolf optimizer (GWO) is used to choose the pixel’s image that would be utilized to insert the hidden image in the cover image. GWO effectively selects pixels by calculating entropy, pixel intensity, and fitness function using the cover images. Moreover, the secret image was encrypted by utilizing a proposed hyper-chaotic improved Henon map and fractal Tromino. The suggested method increases computational security and efficiency with increased embedding capacity. Following the embedding algorithm of the secret image and the alteration of the cover image, the least significant bit (LSB) is utilized to locate the tempered region and to provide self-recovery characteristics in the digital image. According to the findings, the proposed technique provides a more secure transmission network with lower complexity in terms of peak signal-to-noise ratio (PSNR), normalized cross correlation (NCC), structural similarity index (SSIM), entropy and mean square error (MSE). As compared to the current approaches, the proposed method performed better in terms of PSNR 70.58% Db and SSIM 0.999 respectively
Shared and Searchable Encrypted Data for Untrusted Servers
Current security mechanisms pose a risk for organisations that outsource their data management to untrusted servers. Encrypting and decrypting sensitive data at the client side is the normal approach in this situation but has high communication and computation overheads if only a subset of the data is required, for example, selecting records in a database table based on a keyword search. New cryptographic schemes have been proposed that support encrypted queries over encrypted data but all depend on a single set of secret keys, which implies single user access or sharing keys among multiple users, with key revocation requiring costly data re-encryption. In this paper, we propose an encryption scheme where each authorised user in the system has his own keys to encrypt and decrypt data. The scheme supports keyword search which enables the server to return only the encrypted data that satisfies an encrypted query without decrypting it. We provide two constructions of the scheme giving formal proofs of their security. We also report on the results of a prototype implementation.
This research was supported by the UK’s EPSRC research grant EP/C537181/1. The authors would like to thank the members of the Policy Research Group at Imperial College for their support
Optimal Linear Multiparty Conditional Disclosure of Secrets Protocols
In a -party CDS protocol, each party sends one message to a referee (without seeing the other messages) such that the referee will learn a secret held by the parties if and only if the inputs of the parties satisfy some condition (e.g., if the inputs are all equal). This simple primitive is used to construct attribute based encryption, symmetrically-private information retrieval, priced oblivious transfer, and secret-sharing schemes for any access structure. Motivated by these applications, CDS protocols have been recently studied in many papers. In this work, we study linear CDS protocols, where each of the messages of the parties is a linear function of the secret and random elements taken from some finite field. Linearity is an important property of CDS protocols as many applications of CDS protocols required it.
Our main result is a construction of linear -party CDS protocols for an arbitrary function with messages of size . By a lower bound of Beimel et al. [TCC 2017], this message size is optimal. We also consider functions with few inputs that return one, and design more efficient CDS protocols for them.
CDS protocols can be used to construct secret-sharing schemes for uniform access structures, where for some all sets of size less than are unauthorized, all sets of size greater than are authorized, and each set of size can be either authorized or unauthorized. We show that our results imply that every -uniform access structure with parties can be realized by a linear secret-sharing scheme with share size . Furthermore, the linear -party CDS protocol with messages of size was recently used by Liu and Vaikuntanathan [STOC 2018] to construct a linear secret-sharing scheme with share size for any -party access structure
Secure data sharing and processing in heterogeneous clouds
The extensive cloud adoption among the European Public Sector Players empowered them to own and operate a range of cloud infrastructures. These deployments vary both in the size and capabilities, as well as in the range of employed technologies and processes. The public sector, however, lacks the necessary technology to enable effective, interoperable and secure integration of a multitude of its computing clouds and services. In this work we focus on the federation of private clouds and the approaches that enable secure data sharing and processing among the collaborating infrastructures and services of public entities. We investigate the aspects of access control, data and security policy languages, as well as cryptographic approaches that enable fine-grained security and data processing in semi-trusted environments. We identify the main challenges and frame the future work that serve as an enabler of interoperability among heterogeneous infrastructures and services. Our goal is to enable both security and legal conformance as well as to facilitate transparency, privacy and effectivity of private cloud federations for the public sector needs. © 2015 The Authors
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