Multi-Writer Multi-Reader Research Articles

Multi-writer Multi-reader Boolean Keyword Searchable Encryption

In traditional public key searchable encryption (PKSE), a data owner (writer) utilizes data user’s (reader) public key to build ciphertexts. Thus, to share D data items (W keywords per item) with R readers, a writer suffers from $$O(R \cdot D \cdot W)$$ computational overhead. Researchers then offer numerous schemes supporting multiple readers with optimal overhead, i.e., $$O(D \cdot W)$$ . However, these schemes support either a single-keyword search or multi-keyword search in single-writer multi-reader (SWMR) setting where a writer could share data with the known set of readers. On the other hand, the existing multi-writer multi-reader (MWMR) PKSE offers Boolean search but suffers from $$O(R \cdot D \cdot W)$$ computational overhead for each writer. We observe applications desiring PKSE where writers could share data with the unknown set of readers and readers could perform search across data for Boolean query. Since the existing literature lacks such schemes, we propose a multi-writer multi-reader Boolean keyword searchable encryption (MWMR-BKSE) where the separate sets of registered readers and writers are prepared. Once registered, the writer could compute ciphertexts without knowing the potential readers and the readers could search across data at any time. The computational overhead on each writer is optimal $$O(D \cdot W)$$ . Additionally, a deregistered client would not be able to further write or read data. With MWMR-BKSE, we offer a Boolean keyword search utilizing key policy attribute-based encryption. The security of ciphertext against chosen keyword attack is proved using full security model. With the detailed theoretical analysis and extensive simulations on real-world datasets, we demonstrate the effectiveness of MWMR-BKSE.

Multi-Writer Multi-Reader Conjunctive Keyword Searchable Encryption

We explore the area of searchable encryption aiming to identify the schemes supporting multiple data owner (writers) and multiple data users (readers). Especially, we observe multi-writer multi-reader (MWMR) searchable encryption schemes focusing on multi-keyword search. However, such MWMR schemes offer a centralised token generation approach whereby an enterprise trusted authority (ETA) issues a search token to each reader in system, and thus introduce two serious issues, viz. leakage of keywords to ETA and O(q · R) communication overhead for R readers and q queries per reader. In this paper, we alleviate these issues by proposing an MWMR scheme with a decentralised token generation approach. With such an approach, a registered data reader constructs a search token without interacting with ETA and thus provides an efficient token generation with keyword privacy from ETA. Additionally, we incorporate a more expressive especially, conjunctive keyword search with the scheme. With formal security analysis, we prove that the scheme effectively stands against chosen keyword attack performed by inside or outside attacker. With theoretical and empirical analysis, we justify the effectiveness of the proposed scheme.

Linear space bootstrap communication schemes

Consider a system of n processes with ids that are drawn from a large space. How can these n processes communicate to solve a problem? It is shown that linear number of Multi-Writer Multi-Reader (MWMR) registers are sufficient to solve any read-write wait-free solvable problem and needed to solve some read-write wait-free solvable problem. This contrasts with the existing possible solution borrowed from adaptive algorithms that require Θ(n3/2) MWMR registers.To obtain the sufficiency result, the paper shows how the processes can non-blocking emulate a system of n Single-Writer Multi-Reader (SWMR) registers on top of n Multi-Writer Multi-Reader (MWMR) registers. For the necessity result, it shows it is impossible to do such an emulation with n−1 MWMR registers.The paper also presents a wait-free emulation, using 2n−1 rather than just n registers. The emulation can be used to solve an infinite sequence of tasks that are sequentially dependent (processes need the previous task's outputs in order to proceed to the next task). A non-blocking emulation cannot be used in this case, because it might starve a process forever.

Efficient and Robust Sharing of Memory in Message-Passing Systems

A simulation of a wait-free, atomic, single-writer multireader register in an asynchronous message passing system is presented. The simulation can withstand the failure of up to half of the processors and requires O(n) messages (for each read or write operation), assuming there are n+1 processors in the system. It improves on the previous simulation, which requires O(n2) messages (for each read or write operation). The message complexity of the new simulation is within a constant factor of the optimum. The new simulation improves the complexity of algorithms for the following problems in the message-passing model in the presence of processor failures: multiwriter multireader registers, concurrent time-stamp systems, ℓ-exclusion, atomic snapshots, randomized consensus, implementation of data structures, as well as improved fault-tolerant algorithms for any solvable decision task.

Bounded Concurrent Time-Stamping

We introduce concurrent time-stamping, a paradigm that allows processes to temporally order concurrent events in an asynchronous shared-memory system. Concurrent time-stamp systems are powerful tools for concurrency control, serving as the basis for solutions to coordination problems such as mutual exclusion, $\ell$-exclusion, randomized consensus, and multiwriter multireader atomic registers. Unfortunately, all previously known methods for implementing concurrent time-stamp systems have been theoretically unsatisfying since they require unbounded-size time-stamps---in other words, unbounded-size memory. This work presents the first bounded implementation of a concurrent time-stamp system, providing a modular unbounded-to-bounded transformation of the simple unbounded solutions to problems such as those mentioned above. It allows solutions to two formerly open problems, the bounded-probabilistic-consensus problem of Abrahamson and the fifo-$\ell$-exclusion problem of Fischer, Lynch, Burns and Borodin, and a more efficient construction of multireader multiwriter atomic registers.