物件導向軟體之架構(Object-Oriented Software Construction)探討

What is modal logic

This introduction presents the main motivations for the development of Description Logics (DLs) as a formalism for representing knowledge, as well as some important basic notions underlying all systems that have been created in the DL tradition. In addition, we provide the reader with an overview of the entire book and some guidelines for reading it. We first address the relationship between Description Logics and earlier semantic network and frame systems, which represent the original heritage of the field. We delve into some of the key problems encountered with the older efforts. Subsequently, we introduce the basic features of DL languages and related reasoning techniques. DL languages are then viewed as the core of knowledge representation systems, considering both the structure of a DL knowledge base and its associated reasoning services. The development of some implemented knowledge representation systems based on Description Logics and the first applications built with such systems are then reviewed. Finally, we address the relationship of Description Logics to other fields of Computer Science.We also discuss some extensions of the basic representation language machinery; these include features proposed for incorporation in the formalism that originally arose in implemented systems, and features proposed to cope with the needs of certain application domains.

https://assets.cambridge.org/97805218/76254/frontmatter/9780521876254_frontmatter.pdf

The Description Logic Handbook

The objective of this paper is to give a comprehensive introduction to applied cryptography with an engineer or computer scientist in mind. The emphasis is on the knowledge needed to create practical systems which supports integrity, confidentiality, or authenticity. Topics covered includes an introduction to the concepts in cryptography, attacks against cryptographic systems, key use and handling, random bit generation, encryption modes, and message authentication codes. Recommendations on algorithms and further reading is given in the end of the paper. This paper should make the reader able to build, understand and evaluate system descriptions and designs based on the cryptographic components described in the paper.

[서평]「Applied Cryptography」

Usually, a proof of a theorem contains more knowledge than the mere fact that the theorem is true. For instance, to prove that a graph is Hamiltonian it suffices to exhibit a Hamiltonian tour in it; however, this seems to contain more knowledge than the single bit Hamiltonian/non-Hamiltonian.In this paper a computational complexity theory of the “knowledge” contained in a proof is developed. Zero-knowledge proofs are defined as those proofs that convey no additional knowledge other than the correctness of the proposition in question. Examples of zero-knowledge proof systems are given for the languages of quadratic residuosity and 'quadratic nonresiduosity. These are the first examples of zero-knowledge proofs for languages not known to be efficiently recognizable.

/pdf/the-knowledge-complexity-of-interactive-proof-systems-31apre0ecf.pdf

The knowledge complexity of interactive proof-systems

Many cryptographic tasks and protocols, such as non-repudiation, contract-signing, voting, auction, identity-based encryption, and certain forms of secure multi-party computation, involve the use of (semi-)trusted parties, such as notaries and authorities. It is crucial that such parties can be held accountable in case they misbehave as this is a strong incentive for such parties to follow the protocol. Unfortunately, there does not exist a general and convincing definition of accountability that would allow to assess the level of accountability a protocol provides.In this paper, we therefore propose a new, widely applicable definition of accountability, with interpretations both in symbolic and computational models. Our definition reveals that accountability is closely related to verifiability, for which we also propose a new definition. We prove that verifiability can be interpreted as a weak form of accountability. Our findings on verifiability are of independent interest.As a proof of concept, we apply our definitions to the analysis of protocols for three different tasks: contract-signing, voting, and auctions. Our analysis unveils some subtleties and unexpected weaknesses, showing in one case that the protocol is unusable in practice. However, for this protocol we propose a fix to establish a reasonable level of accountability.

Accountability: definition and relationship to verifiability

The OAuth 2.0 protocol is one of the most widely deployed authorization/single sign-on (SSO) protocols and also serves as the foundation for the new SSO standard OpenID Connect. Despite the popularity of OAuth, so far analysis efforts were mostly targeted at finding bugs in specific implementations and were based on formal models which abstract from many web features or did not provide a formal treatment at all. In this paper, we carry out the first extensive formal analysis of the OAuth 2.0 standard in an expressive web model. Our analysis aims at establishing strong authorization, authentication, and session integrity guarantees, for which we provide formal definitions. In our formal analysis, all four OAuth grant types (authorization code grant, implicit grant, resource owner password credentials grant, and the client credentials grant) are covered. They may even run simultaneously in the same and different relying parties and identity providers, where malicious relying parties, identity providers, and browsers are considered as well. Our modeling and analysis of the OAuth 2.0 standard assumes that security recommendations and best practices are followed in order to avoid obvious and known attacks. When proving the security of OAuth in our model, we discovered four attacks which break the security of OAuth. The vulnerabilities can be exploited in practice and are present also in OpenID Connect. We propose fixes for the identified vulnerabilities, and then, for the first time, actually prove the security of OAuth in an expressive web model. In particular, we show that the fixed version of OAuth (with security recommendations and best practices in place) provides the authorization, authentication, and session integrity properties we specify.

A Comprehensive Formal Security Analysis of OAuth 2.0

Description Logics.- Non-Standard Inferences.- Characterizing Subsumption.- LCS and MSC.- Matching.- Conclusion.

Non-standard inferences in description logics

ProVerif is one of the most successful tools for cryptographic protocol analysis. However, dealing with algebraic properties of operators such as the exclusive OR (XOR) and Diffie-Hellman exponentiation has been problematic. Recently, we have developed an approach which enables ProVerif, and related tools, to analyze a large class of protocols that employ the XOR operator. In this work, we adapt this approach to the case of Diffie-Hellman exponentiation. The core of our approach is to reduce the derivation problem for Horn theories modulo algebraic properties of Diffie-Hellman exponentiation to a purely syntactical derivation problem for Horn theories. The latter problem can then be solved by tools such as ProVerif. Our reduction works for a large class of Horn theories, allowing to model a wide range of intruder capabilities and protocols. We implemented our reduction and, in combination with ProVerif, applied it in the automatic analysis of several state-of-the-art protocols that use Diffie-Hellman exponentiation. While the general idea of our approach follows the one for XOR in our previous work, the reduction itself and the proof of soundness and completeness of our reduction are entirely different from the XOR case. Surprisingly, the reduction for Diffie-Hellman exponentiation is more efficient than the one for XOR.

Using ProVerif to Analyze Protocols with Diffie-Hellman Exponentiation

We present an NP decision procedure for the formal analysis of protocols in presence of modular exponentiation with products allowed in exponents. The number of factors that may appear in the products is unlimited. We illustrate that our model is powerful enough to uncover known attacks on the A-GDH.2 protocol suite.

Deciding the Security of Protocols with Diffie-Hellman Exponentiation and Products in Exponents

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