5,178 research outputs found
Secure Group Communication Using Fractional Public Keys
In this paper, we present the novel concept of fractional public keys and an efficient zero-round multi-party Diffie-Hellman key agreement scheme that is based on fractional public keys. Shared group keys are computed highly efficiently by using the fractional public keys of multiple participants as exponents. The scheme provides therefore an efficient and elegant way of multi-party key agreement without key establishment data transmissions. The presented cryptographic scheme is collusion resistant to any number of users
Longitude : a privacy-preserving location sharing protocol for mobile applications
Location sharing services are becoming increasingly popular. Although many location sharing services allow users to set up privacy policies to control who can access their location, the use made by service providers remains a source of concern. Ideally, location sharing providers and middleware should not be able to access usersā location data without their consent. In this paper, we propose a new location sharing protocol called Longitude that eases privacy concerns by making it possible to share a userās location data blindly and allowing the user to control who can access her location, when and to what degree of precision. The underlying cryptographic algorithms are designed for GPS-enabled mobile phones. We describe and evaluate our implementation for the Nexus One Android mobile phone
Analysis of common attacks in LDPCC-based public-key cryptosystems
We analyze the security and reliability of a recently proposed class of
public-key cryptosystems against attacks by unauthorized parties who have
acquired partial knowledge of one or more of the private key components and/or
of the plaintext. Phase diagrams are presented, showing critical partial
knowledge levels required for unauthorized decryptionComment: 14 pages, 6 figure
Cloud-based Quadratic Optimization with Partially Homomorphic Encryption
The development of large-scale distributed control systems has led to the
outsourcing of costly computations to cloud-computing platforms, as well as to
concerns about privacy of the collected sensitive data. This paper develops a
cloud-based protocol for a quadratic optimization problem involving multiple
parties, each holding information it seeks to maintain private. The protocol is
based on the projected gradient ascent on the Lagrange dual problem and
exploits partially homomorphic encryption and secure multi-party computation
techniques. Using formal cryptographic definitions of indistinguishability, the
protocol is shown to achieve computational privacy, i.e., there is no
computationally efficient algorithm that any involved party can employ to
obtain private information beyond what can be inferred from the party's inputs
and outputs only. In order to reduce the communication complexity of the
proposed protocol, we introduced a variant that achieves this objective at the
expense of weaker privacy guarantees. We discuss in detail the computational
and communication complexity properties of both algorithms theoretically and
also through implementations. We conclude the paper with a discussion on
computational privacy and other notions of privacy such as the non-unique
retrieval of the private information from the protocol outputs
A Novel Image Encryption Using an Integration Technique of Blocks Rotation Based on the Magic Cube and the AES Algorithm
In recent years, several encryption algorithms have been proposed to protect
digital images from cryptographic attacks. These encryption algorithms
typically use a relatively small key space and therefore, provide safe,
especially if they are of a dimension. In this paper proposes an encryption
algorithm for a new image protection scheme based on the rotation of the faces
of a Magic Cube. The original image is divided into six sub-images and these
sub-images are divided amongst a number of blocks and attached to the faces of
a Magic Cube. The faces are then scrambled using rotation of the Magic Cube.
Then the rotated image is fed to the AES algorithm which is applied to the
pixels of the image to encrypt the scrambled image. Finally, experimental
results and security analysis show that the proposed image encryption scheme
not only encrypts the picture to achieve perfect hiding, but the algorithm can
also withstand exhaustive, statistical and differential attacks
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