A simple abstraction for complex concurrent indexes

Pinto, Pedro da Rocha; Dinsdale-Young, Thomas; Dodds, Mike; Gardner, Philippa; Wheelhouse, Mark

doi:10.1145/2076021.2048131

Cited by 13 publications

(18 citation statements)

References 19 publications

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“…is present in a term) is stored (Line 3). Note that this search can be implemented by utilising B-Trees [10,29] for indexing the keys. For each of the candidate ID values in the range (Line 4), we retrieve the encrypted triple for such ID by searching for this ID in the EncTriples Index (Line 5).…”

Section: Optimising Query Execution Over Encrypted Rdfmentioning

confidence: 99%

Self-Enforcing Access Control for Encrypted RDF

et al. 2017

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Abstract. The amount of raw data exchanged via web protocols is steadily increasing. Although the Linked Data infrastructure could potentially be used to selectively share RDF data with different individuals or organisations, the primary focus remains on the unrestricted sharing of public data. In order to extend the Linked Data paradigm to cater for closed data, there is a need to augment the existing infrastructure with robust security mechanisms. At the most basic level both access control and encryption mechanisms are required. In this paper, we propose a flexible and dynamic mechanism for securely storing and efficiently querying RDF datasets. By employing an encryption strategy based on Functional Encryption (FE) in which controlled data access does not require a trusted mediator, but is instead enforced by the cryptographic approach itself, we allow for fine-grained access control over encrypted RDF data while at the same time reducing the administrative overhead associated with access control management.

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Section: Optimising Query Execution Over Encrypted Rdfmentioning

confidence: 99%

Self-Enforcing Access Control for Encrypted RDF

et al. 2017

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“…For example, the definition of the in rem (h, k, v) i predicate will include a REM capability for k with permission (g, i), so that any thread may remove the key from the tree, as well as all INS capabilities for k with permission (d, i), so that no thread may insert values for the key into the tree. The full definitions of the predicates may be found in the technical report [5].…”

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confidence: 99%

A simple abstraction for complex concurrent indexes

Pinto

Dinsdale-Young

Dodds

et al. 2011

Proceedings of the 2011 ACM International Conference on Object Oriented Programming Systems Languages and Applications

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Indexes are ubiquitous. Examples include associative arrays, dictionaries, maps and hashes used in applications such as databases, file systems and dynamic languages. Abstractly, a sequential index can be viewed as a partial function from keys to values. Values can be queried by their keys, and the index can be mutated by adding or removing mappings. Whilst appealingly simple, this abstract specification is insufficient for reasoning about indexes that are accessed concurrently.We present an abstract specification for concurrent indexes. We verify several representative concurrent client applications using our specification, demonstrating that clients can reason abstractly without having to consider specific underlying implementations. Our specification would, however, mean nothing if it were not satisfied by standard implementations of concurrent indexes. We verify that our specification is satisfied by algorithms based on linked lists, hash tables and B Link trees. The complexity of these algorithms, in particular the B Link tree algorithm, can be completely hidden from the client's view by our abstract specification.General Terms Algorithms, Concurrency, Theory, Verification.

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“…This idea has been successfully applied to the specification and verification of indexing structures [4]. The work presented here cannot substitute capabilities.…”

Section: Discussionmentioning

confidence: 99%

“…5 to prove that, at the end of the execution, l i s t 1 contains the sequence [1,4,3], and l i s t 2 contains [1,2,3]. Behind the scenes however, the data structure performs lazy copying: all operations are implemented with reference manipulations as long as this does not influence the clients' disjointness illusion.…”

Section: =New L I S T ; I N I T E M P T Y ( L I S T 1 ) ;mentioning

confidence: 99%

A Discipline for Program Verification Based on Backpointers and Its Use in Observational Disjointness

Kassios

Kritikos

2013

Programming Languages and Systems

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Abstract. In the verification of programs that manipulate the heap, logics that emphasize localized reasoning, such as separation logic, are being used extensively. In such logics, state conditions may only refer to parts of the heap that are reachable from the stack. However, the correct implementation of some data structures is based on state conditions that depend on unreachable locations. For example, reference counting depends on the invariant that "the number of nodes pointing to a certain node is equal to its reference counter ". Such conditions are cumbersome or even impossible to formalize in existing variants of separation logic. In the first part of this paper, we develop a minimal programming discipline that enables the programmer to soundly express backpointer conditions, i.e., state conditions that involve heap objects that point to the reachable part of the heap, such as the above-mentioned reference counting invariant. In the second part, we demonstrate the expressiveness of our methodology by verifying the implementation of concurrent copy-on-write lists (CCoWL). CCoWL is a data structure with observational disjointness, i.e., its specification pretends that different lists depend on disjoint parts of the heap, so that separation logic reasoning is made easy, while its implementation uses sharing to maximize performance. The CCoWL case study is a very challenging problem, to which we are not aware of any other solutions.

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A simple abstraction for complex concurrent indexes

Cited by 13 publications

References 19 publications

Self-Enforcing Access Control for Encrypted RDF

Self-Enforcing Access Control for Encrypted RDF

A simple abstraction for complex concurrent indexes

A Discipline for Program Verification Based on Backpointers and Its Use in Observational Disjointness

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