Secret Key Cryptosystem based on Non-Systematic Polar Codes

Polar codes are a new class of error correcting linear block codes, whose generator matrix is specified by the knowledge of transmission channel parameters, code length and code dimension. Moreover, regarding computational security, it is assumed that an attacker with a restricted processing power has unlimited access to the transmission media. Therefore, the attacker can construct the generator matrix of polar codes, especially in the case of Binary Erasure Channels, on which this matrix can be easily constructed. In this paper, we introduce a novel method to keep the generator matrix of polar codes in secret in a way that the attacker cannot access the required information to decode the intended polar code. With the help of this method, a secret key cryptosystem is proposed based on non-systematic polar codes. In fact, the main objective of this study is to achieve an acceptable level of security and reliability through taking advantage of the special properties of polar codes. The analyses revealed that our scheme resists the typical attacks on the secret key cryptosystems based on linear block codes. In addition, by employing some efficient methods, the key length of the proposed scheme is decreased compared to that of the previous cryptosystems. Moreover, this scheme enjoys other advantages including high code rate, and proper error performance as well

Turbo Codes Can Be Asymptotically Information-Theoretically Secure

This paper shows that a turbo-coded communication system can be made secure with a little bit of complexity cost. The classical permutation ciphers are revisited and analyzed. Firstly, the ideal stream permutation ciphers are shown to be asymptotically information-theoretically secure in the sense that the channel from plaintext to ciphertext has a vanished capacity, while the practical stream permutation ciphers are shown to be more secure than the classical stream ciphers in terms of protecting keys. Secondly, a necessary condition to break down a block permutation cipher is derived, which is then utilized to guarantee the computational security of a modified block permutation cipher. Thirdly, turbo ciphers (turbo-like codes with private interleavers) are proposed and analyzed

Joint Schemes for Physical Layer Security and Error Correction

The major challenges facing resource constraint wireless devices are error resilience, security and speed. Three joint schemes are presented in this research which could be broadly divided into error correction based and cipher based. The error correction based ciphers take advantage of the properties of LDPC codes and Nordstrom Robinson code. A cipher-based cryptosystem is also presented in this research. The complexity of this scheme is reduced compared to conventional schemes. The securities of the ciphers are analyzed against known-plaintext and chosen-plaintext attacks and are found to be secure. Randomization test was also conducted on these schemes and the results are presented. For the proof of concept, the schemes were implemented in software and hardware and these shows a reduction in hardware usage compared to conventional schemes. As a result, joint schemes for error correction and security provide security to the physical layer of wireless communication systems, a layer in the protocol stack where currently little or no security is implemented. In this physical layer security approach, the properties of powerful error correcting codes are exploited to deliver reliability to the intended parties, high security against eavesdroppers and efficiency in communication system. The notion of a highly secure and reliable physical layer has the potential to significantly change how communication system designers and users think of the physical layer since the error control codes employed in this work will have the dual roles of both reliability and security

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

Threat Modeling Solution for Internet of Things in a Web­based Security Framework

The Internet of Things (IoT) is a growing paradigm that provides daily life benefits for its users, motivating a fast paced deployment of IoT devices in sensitive scenarios. However, current IoT devices do not correctly apply or integrate security controls or technology, potentially leading to a wide panoply of problems, most of them with harmful impact to the user. Thus, this work proposes the development of a tool that helps developers create properly secure IoT devices by identifying possible weaknesses in the system. This tool consists of a module of a framework, denominated Security Advising Modules (SAM) in the scope of this work, and achieves the referred objective by identifying possible weaknesses found in the software and hardware of IoT devices. To define the weaknesses, a set of databases containing information about vulnerabilities and weaknesses found in a system were investigated throughout this project, and a restricted set of weaknesses to be presented was chosen. Since some databases contain hundreds of thousands of vulnerabilities, it was neither feasible nor pertinent to present them completely in the developed tool. Additionally, the questions to retrieve system information were identified in this work, allowing us to map the chosen weaknesses to the answers given by the developer to those questions. The tool developed was properly tested by running automated tests, with the Selenium framework, and also validated by security experts and evaluated by a set of 18 users. Finally, based on user feedback, it was concluded that the developed tool was useful, simple and straightforward to use, and that 89% of respondents had never interacted with a similar tool (adding, in this way, to the innovative character).A Internet das Coisas (do inglês Internet of Things, IoT) é um paradigma em acentuado crescimento com benefícios inegáveis para o dia a dia dos utilizadores, com uma elevada aplicação dos dispositivos da IoT em cenários sensíveis. No entanto, atualmente os dispositivos da IoT não garantem corretamente as propriedades de segurança, o que pode levar a toda uma panóplia de problemas, muitos com impacto no utilizador. Este trabalho propõe o desenvolvimento de uma ferramenta que auxilie os programadores a criar dispositivos da IoT seguros. A ferramenta é um módulo de uma framework denominada Security Advising Modules (SAM), e procura atingir o referido objetivo através da identificação de fraquezas que possam existir no software ou hardware dos dispositivos IoT. Com o objetivo de delinear as fraquezas, consultou­se ao longo deste projeto um conjunto de bases de dados que contêm informações sobre vulnerabilidades e fraquezas encontradas em sistemas, do qual se escolheram um conjunto restrito de fraquezas a apresentar. A escolha deste conjunto deve­se a algumas das bases de dados consultadas conterem centenas de milhares de vulnerabilidades, pelo que não é exequível nem pertinente a sua completa apresentação na nossa ferramenta. Complementarmente, identificaramse neste trabalho as questões que permitem obter informações sobre o sistema em desenvolvimento que depois nos permitem mapear as fraquezas em função das respostas do programador. A ferramenta desenvolvida foi devidamente testada através da execução de testes automáticos, com a framework Selenium, e também validada por especialistas de segurança e avaliada por um conjunto de 18 utilizadores. Por fim, com base no feedback dos utilizadores, concluiu­se que a ferramenta desenvolvida era útil, de utilização simples e direta, e que 89% dos inquiridos nunca tinham interagido com uma ferramenta similar (nesse sentido inovadora).The work described in this dissertation was carried out at the Instituto de Telecomunicações, Multimedia Signal Processing ­ Cv Laboratory, in Universidade da Beira Interior, at Covilhã, Portugal. This research work was funded by the S E C U R I o T E S I G N Project through FCT/COMPETE/FEDER under Reference Number POCI­01­0145­FEDER­030657 and by Fundação para Ciência e Tecnologia (FCT) research grant with reference BIL/ Nº12/2019­B00702