665 research outputs found
Mental Card Gaming Protocols Supportive Of Gameplay Versatility, Robustness And Efficiency
Pennainan kad mental merupakan protokol kriptografi yang membolehkan pennainan yang
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disahkan adil di kalangan parti-parti jauh yang penyangsi dan berpotensi menipu. Pennainan
kad ini setidak-tidaknya patut menyokong-tanpa memperkenal~an parti ketiga yang dipercayai
(TTP)--rahsia kad, pengesanan penipuan dan keselamatan bersyarat ke atas pakatan pemain.
Tambahan kepada keperJuan asas ini, kami meninjau isu-isu pennainan kad mental yang
berkaitan dengan fungsian permainan, keteguhan operasional dan kecekapan implementasi.
Pengkajian kami diberangsang oleh potensi pennainan berasaskan komputer dan rangkaian yang
melewati batas kemampuan kad fizikal, terutamanya pembongkaran maklumat terperinci kad
(seperti warna, darjat, simbol atau kebangsawanan) sambil merahsiakan nilai keseluruhan kad
tersebut.
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Mental card games are cryptographic protocols which permit verifiably fair gameplay among a
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priori distrustful and potentially untrustworthy remote parties and should minimally providewithout
the introduction of a trusted third party (TTP)---for card confidentiality, fraud detection
and conditional security against collusion. In addition to these basic requirements, we explore
into gameplay functionality, operational robustness and implementation efficiency issues of
mental card gaming. Our research is incited by the potential of computer-based and networkmediated
gameplay beyond the capability of physical cards, particularly fine-grained
information disclosure (such as colour, rank, symbol or courtliness) with preservation of card
secrecy. On the other hand, being network connected renders the protocol susceptible to
(accidental or intentional) disconnection attack, as well as other malicious behaviours
Symmetric private information retrieval via additive homomorphic probabilistic encryption
Suppose there is a movie you would be interested in watching via pay-per-view, but you refuse to purchase the feed because you believe that the supplier will sell your information to groups paying for the contact information of all the people who purchased that movie, and the association of your name to that purchase could hinder career, relationships, or increase the amount of time you spend cleaning SPAM out of your mailbox. Private Information Retrieval (PIR) will allow you to retrieve a particular feed without the supplier knowing which feed you actually got, and Symmetric Private Information Retrieval (SPIR) will assure the supplier, if the feeds are equally priced, that you received only the number of feeds you purchased. Now you can purchase without risking your name being associated with a particular feed and the supplier has gained the business of a once paranoid client. The problem of SPIR can be achieved with the cryptographic primitive Oblivious Transfer (OT). Several approaches to constructing such protocols have been posed and proven to be secure. Most attempts have aimed at reducing the amount of communication, theoretically, but this thesis compares the computational expense of the algorithms through experimentation to show that reduction of communication is less valuable in the effort of achieving a practical protocol than reducing the amount of computation. Further, this thesis introduces new protocols to compete with previous published protocols that derive security from additive homomorphic probabilistic encryption schemes, and explores means to increase the length of data handled by these protocols so that the media is more useful and the time to complete the protocol is reasonable
Homomorphic Encryption for Speaker Recognition: Protection of Biometric Templates and Vendor Model Parameters
Data privacy is crucial when dealing with biometric data. Accounting for the
latest European data privacy regulation and payment service directive,
biometric template protection is essential for any commercial application.
Ensuring unlinkability across biometric service operators, irreversibility of
leaked encrypted templates, and renewability of e.g., voice models following
the i-vector paradigm, biometric voice-based systems are prepared for the
latest EU data privacy legislation. Employing Paillier cryptosystems, Euclidean
and cosine comparators are known to ensure data privacy demands, without loss
of discrimination nor calibration performance. Bridging gaps from template
protection to speaker recognition, two architectures are proposed for the
two-covariance comparator, serving as a generative model in this study. The
first architecture preserves privacy of biometric data capture subjects. In the
second architecture, model parameters of the comparator are encrypted as well,
such that biometric service providers can supply the same comparison modules
employing different key pairs to multiple biometric service operators. An
experimental proof-of-concept and complexity analysis is carried out on the
data from the 2013-2014 NIST i-vector machine learning challenge
Progress on probabilistic encryption schemes
The purpose of this master\u27s project is to study different probabilistic cryptography schemes. The older probabilistic schemes, Goldwasser-Micali and Blum-Goldwasser, will only be covered briefly for a historical perspective. Several new and promising schemes have appeared in the last 7 years, generating interest. I will be examining the Paillier and Damgard-Jurik schemes in depth. This report explains the mathematics behind the schemes along with their inherent benefits, while also suggesting some potential uses. Details are given on how I optimized the algorithms, with special emphasis on using the Chinese Remainder Theorem (CRT) in the Damgard-Jurik algorithm as well as the other algorithms. One of the main benefits these schemes posses is the additively homomorphic property. I explain the homomorphic properties in the description of the schemes and give an overview of these properties in Appendix A. I create software based in the Java Cryptography Extension (JCE) that is used to do a comparative study. This includes a simple message passing program for encrypted text. I create my own implementations of Paillier, Damgard-Jurik, and a variation of Paillier\u27s scheme as a Provider using the JCE. These implementations use the CRT along with other methods to increase performance and create optimized algorithms. The implementations are plugged into the message passing program with an implementation of RSA from another Provider. A comparative study of the timings of these three schemes is done to show which one performs better in different circumstances. Conclusions are drawn based on the results of the tests and my final opinions are stated
A Survey on Homomorphic Encryption Schemes: Theory and Implementation
Legacy encryption systems depend on sharing a key (public or private) among
the peers involved in exchanging an encrypted message. However, this approach
poses privacy concerns. Especially with popular cloud services, the control
over the privacy of the sensitive data is lost. Even when the keys are not
shared, the encrypted material is shared with a third party that does not
necessarily need to access the content. Moreover, untrusted servers, providers,
and cloud operators can keep identifying elements of users long after users end
the relationship with the services. Indeed, Homomorphic Encryption (HE), a
special kind of encryption scheme, can address these concerns as it allows any
third party to operate on the encrypted data without decrypting it in advance.
Although this extremely useful feature of the HE scheme has been known for over
30 years, the first plausible and achievable Fully Homomorphic Encryption (FHE)
scheme, which allows any computable function to perform on the encrypted data,
was introduced by Craig Gentry in 2009. Even though this was a major
achievement, different implementations so far demonstrated that FHE still needs
to be improved significantly to be practical on every platform. First, we
present the basics of HE and the details of the well-known Partially
Homomorphic Encryption (PHE) and Somewhat Homomorphic Encryption (SWHE), which
are important pillars of achieving FHE. Then, the main FHE families, which have
become the base for the other follow-up FHE schemes are presented. Furthermore,
the implementations and recent improvements in Gentry-type FHE schemes are also
surveyed. Finally, further research directions are discussed. This survey is
intended to give a clear knowledge and foundation to researchers and
practitioners interested in knowing, applying, as well as extending the state
of the art HE, PHE, SWHE, and FHE systems.Comment: - Updated. (October 6, 2017) - This paper is an early draft of the
survey that is being submitted to ACM CSUR and has been uploaded to arXiv for
feedback from stakeholder
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