A Canonical Form for PROV Documents and its Application to Equality, Signature, and Validation

We present a canonical form for prov that is a normalized way of representing prov documents as mathematical expressions. As opposed to the normal form specified by the prov-constraints recommendation, the canonical form we present is defined for all prov documents, irrespective of their validity, and it can be serialized in a unique way. The article makes the case for a canonical form for prov and its potential uses, namely comparison of prov documents in different formats, validation, and signature of prov documents. A signature of a prov document allows the integrity and the author of provenance to be ascertained; since the signature is based on the canonical form, these checks are not tied to a particular encoding, but can be performed on any representation of prov . </jats:p

From Sets to Bits in Coq

International audienceComputer Science abounds in folktales about how — in the early days of computer programming — bit vectors were ingeniously used to encode and manipulate finite sets. Algorithms have thus been developed to minimize memory footprint and maximize efficiency by taking advantage of microarchitectural features. With the development of automated and interactive theorem provers, finite sets have also made their way into the libraries of formalized mathematics. Tailored to ease proving , these representations are designed for symbolic manipulation rather than computational efficiency. This paper aims to bridge this gap. In the Coq proof assistant, we implement a bitset library and prove its correct-ness with respect to a formalization of finite sets. Our library enables a seamless interaction of sets for computing — bitsets — and sets for proving — finite sets

Reflection in conditional rewriting logic

AbstractWe recall general metalogical axioms for a reflective logic based on the notion of a universal theory, that is, a theory that can simulate the deductions of all other theories in a class of theories of interest, including itself. We then show that conditional rewriting logic is reflective, generalizing in two stages: first to the unsorted conditional case, and then to the many-sorted conditional case, the already known result for unconditional and unsorted rewriting logic (Reflection in Rewriting Logic: Metalogical Foundations and Metaprogramming Applications. CSLI Publications, 2000). This work should be seen as providing foundations for many useful applications of rewriting logic reflection. The results presented here have greatly influenced the design of the Maude language, which implements rewriting logic and supports its reflective capabilities, and have been used as a theoretical foundation for applications such as internal rewrite strategies, reflective design of theorem proving tools, module algebra and metaprogramming, and metareasoning in metalogical frameworks

Specification and implementation of the Larch shared language

This project aims to prototype formal specification in Larch. The motivation for looking at formal specifications stems from an appreciation of the problem outlined above, frustration with current methods, and a desire to practise what is preached. The aim is to implement a formal specification language, to write a non-trivial specification and to employ formal methods of specification during software development. As a result, one should have a thorough understanding of a formal specification language, and the practical implications of using it as a basis for formal methods

Bringing data minimization to digital wallets at scale with general-purpose zero-knowledge proofs

Today, digital identity management for individuals is either inconvenient and error-prone or creates undesirable lock-in effects and violates privacy and security expectations. These shortcomings inhibit the digital transformation in general and seem particularly concerning in the context of novel applications such as access control for decentralized autonomous organizations and identification in the Metaverse. Decentralized or self-sovereign identity (SSI) aims to offer a solution to this dilemma by empowering individuals to manage their digital identity through machine-verifiable attestations stored in a "digital wallet" application on their edge devices. However, when presented to a relying party, these attestations typically reveal more attributes than required and allow tracking end users' activities. Several academic works and practical solutions exist to reduce or avoid such excessive information disclosure, from simple selective disclosure to data-minimizing anonymous credentials based on zero-knowledge proofs (ZKPs). We first demonstrate that the SSI solutions that are currently built with anonymous credentials still lack essential features such as scalable revocation, certificate chaining, and integration with secure elements. We then argue that general-purpose ZKPs in the form of zk-SNARKs can appropriately address these pressing challenges. We describe our implementation and conduct performance tests on different edge devices to illustrate that the performance of zk-SNARK-based anonymous credentials is already practical. We also discuss further advantages that general-purpose ZKPs can easily provide for digital wallets, for instance, to create "designated verifier presentations" that facilitate new design options for digital identity infrastructures that previously were not accessible because of the threat of man-in-the-middle attacks

Language-based Enforcement of User-defined Security Policies (As Applied to Multi-tier Web Programs)

Over the last 35 years, researchers have proposed many different forms of security policies to control how information is managed by software, e.g., multi-level information flow policies, role-based or history-based access control, data provenance management etc. A large body of work in programming language design and analysis has aimed to ensure that particular kinds of security policies are properly enforced by an application. However, these approaches typically fix the style of security policy and overall security goal, e.g., information flow policies with a goal of noninterference. This limits the programmer's ability to combine policy styles and to apply customized enforcement techniques while still being assured the system is secure. This dissertation presents a series of programming-language calculi each intended to verify the enforcement of a range of user-defined security policies. Rather than ``bake in'' the semantics of a particular model of security policy, our languages are parameterized by a programmer-provided specification of the policy and enforcement mechanism (in the form of code). Our approach relies on a novel combination of dependent types to correctly associate security policies with the objects they govern, and affine types to account for policy or program operations that include side effects. We have shown that our type systems are expressive enough to verify the enforcement of various forms of access control, provenance, information flow, and automata-based policies. Additionally, our approach facilitates straightforward proofs that programs implementing a particular policy achieve their high-level security goals. We have proved our languages sound and we have proved relevant security properties for each of the policies we have explored. To our knowledge, no prior framework enables the enforcement of such a wide variety of security policies with an equally high level of assurance. To evaluate the practicality of our solution, we have implemented one of our type systems as part of the Links web-programming language; we call the resulting language SELinks. We report on our experience using SELinks to build two substantial applications, a wiki and an on-line store, equipped with a combination of access control and provenance policies. In general, we have found the mechanisms SELinks provides to be both sufficient and relatively easy to use for many common policies, and that the modular separation of user-defined policy code permitted some reuse between the two applications

Automated Deduction – CADE 28

This open access book constitutes the proceeding of the 28th International Conference on Automated Deduction, CADE 28, held virtually in July 2021. The 29 full papers and 7 system descriptions presented together with 2 invited papers were carefully reviewed and selected from 76 submissions. CADE is the major forum for the presentation of research in all aspects of automated deduction, including foundations, applications, implementations, and practical experience. The papers are organized in the following topics: Logical foundations; theory and principles; implementation and application; ATP and AI; and system descriptions