Trusted third party

About: Trusted third party is a research topic. Over the lifetime, 2919 publications have been published within this topic receiving 60935 citations.

Replicated Data Integrity Verification in Cloud

Abstract: Cloud computing is an emerging model in which computing infrastructure resources are provided as a service over the Internet. Data owners can outsource their data by remotely storing them in the cloud and enjoy on-demand high quality applications and services from a shared pool of configurable computing resources. However, since data owners and cloud servers are not in the same trusted domain, the outsourced data may be at risk as the cloud server may no longer be fully trusted. Therefore, data integrity is of critical importance in such a scenario. Cloud should let either the owners or a trusted third party to audit their data storage without demanding a local copy of the data from owners. Replicating data on cloud servers across multiple data centers provides a higher level of scalability, availability, and durability. When the data owners ask the Cloud Service Provider (CSP) to replicate data at different servers, they are charged a higher fee by the CSP. Therefore, the data owners need to be strongly convinced that the CSP is storing all the data copies that are agreed upon in the service level contract, and the data-update requests issued by the customers have been correctly executed on all the remotely stored copies. To deal with such problems, previous multi copy verification schemes either focused on static files or incurred huge update costs in a dynamic file scenario. In this paper, we propose some ideas under a Dynamic Multi-Replica Provable Data Possession scheme (DMR-PDP) that prevents the CSP from cheating; for example, by maintaining fewer copies than paid for. DMR-PDP also supports efficient dynamic operations like block modification, insertion and deletion on data replicas over cloud servers.

Controlled mutual quantum entity authentication using entanglement swapping

Abstract: In this paper, we suggest a controlled mutual quantum entity authentication protocol by which two users mutually certify each other on a quantum network using a sequence of Greenberger–Horne–Zeilinger (GHZ)-like states. Unlike existing unidirectional quantum entity authentication, our protocol enables mutual quantum entity authentication utilizing entanglement swapping; moreover, it allows the managing trusted center (TC) or trusted third party (TTP) to effectively control the certification of two users using the nature of the GHZ-like state. We will also analyze the security of the protocol and quantum channel.

Electronic Contract Signing Without Using Trusted Third Party

Abstract: Electronic contract signing allows two potentially dis-trustful parties to digitally sign an electronic document “simultaneously” across a network. Existing solutions for electronic contract signing either require the involvement of a trusted third party (TTP), or are complex and expensive in communication and computation. In this paper we propose an electronic contract signing protocol between two parties with the following advantages over existing solutions: 1) it is practical and scalable due to its simplicity and high efficiency; 2) it does not require any trusted third party as the mediator; and 3) it guarantees fairness between the two signing parties. We achieve these properties by employing a trustworthy timestamping service in our protocol, where the timestamping service can be either centralized or decentralized. We also provide a detailed analysis on security and performance of our scheme.

Attribute-Based Keyword Search Efficiency Enhancement via an Online/Offline Approach

Abstract: Searchable encryption is a primitive, which not only protects data privacy of data owners but also enables data users to search over the encrypted data. Most existing searchable encryption schemes are in the single-user setting. There are only few schemes in the multiple data users setting, i.e., encrypted data sharing. Among these schemes, most of the early techniques depend on a trusted third party with interactive search protocols or need cumbersome key management. To remedy the defects, the most recent approaches borrow ideas from attribute-based encryption to enable attribute-based keyword search (ABKS). However, all these schemes incur high computational costs and are not suitable for mobile devices, such as mobile phones, with power consumption constraints. In this paper, we develop new techniques that split the computation for the keyword encryption and trapdoor/token generation into two phases: a preparation phase that does the vast majority of the work to encrypt a keyword or create a token before it knows the keyword or the attribute list/access control policy that will be used. A second phase then rapidly assembles an intermediate ciphertext or trapdoor when the specifics become known. The preparation work can be performed while the mobile device is plugged into a power source, then it can later rapidly perform keyword encryption or token generation operations on the move without significantly draining the battery. We name our scheme Online/Offline ABKS. To the best of our knowledge, this is the first work on constructing efficient multi-user searchable encryption scheme for mobile devices through moving the majority of the cost of keyword encryption and token generation into an offline phase.