A Hybrid Computational Intelligence based Technique for Automatic Cryptanalysis of Playfair Ciphers

The Playfair cipher is a symmetric key cryptosystem-based on encryption of digrams of letters. The cipher shows higher cryptanalytic complexity compared to mono-alphabetic cipher due to the use of 625 different letter-digrams in encryption instead of 26 letters from Roman alphabets. Population-based techniques like Genetic algorithm (GA) and Swarm intelligence (SI) are more suitable compared to the Brute force approach for cryptanalysis of cipher because of specific and unique structure of its Key Table. This work is an attempt to automate the process of cryptanalysis using hybrid computational intelligence. Multiple particle swarm optimization (MPSO) and GA-based hybrid technique (MPSO-GA) have been proposed and applied in solving Playfair ciphers. The authors have attempted to find the solution key applied in generating Playfair crypts by using the proposed hybrid technique to reduce the exhaustive search space. As per the computed results of the MPSO-GA technique, correct solution was obtained for the Playfair ciphers of 100 to 200 letters length. The proposed technique provided better results compared to either GA or PSO-based technique. Furthermore, the technique was also able to recover partial English text message for short Playfair ciphers of 80 to 120 characters length

Data Encryption and Decryption Using Hill Cipher Method and Self Repetitive Matrix

Since times immemorial, security of data to maintain its confidentiality, proper access control, integrity and availability has been a major issue in data communication. As soon as a sensitive message was etched on a clay tablet or written on the royal walls, then it must have been foremost in the sender’s mind that the information should not get intercepted and read by a rival. Codes, hence, form an important part of our history, starting from the paintings of Da Vinci and Michelangelo to the ancient Roman steganographic practices the necessity of data hiding was obvious

E‐ART: a new encryption algorithm based on the reflection of binary search tree

Data security has become crucial to most enterprise and government applications due to the increasing amount of data generated, collected, and analyzed. Many algorithms have been developed to secure data storage and transmission. However, most existing solutions require multi-round functions to prevent differential and linear attacks. This results in longer execution times and greater memory consumption, which are not suitable for large datasets or delay-sensitive systems. To address these issues, this work proposes a novel algorithm that uses, on one hand, the reflection property of a balanced binary search tree data structure to minimize the overhead, and on the other hand, a dynamic offset to achieve a high security level. The performance and security of the proposed algorithm were compared to Advanced Encryption Standard and Data Encryption Standard symmetric encryption algorithms. The proposed algorithm achieved the lowest running time with comparable memory usage and satisfied the avalanche effect criterion with 50.1%. Furthermore, the randomness of the dynamic offset passed a series of National Institute of Standards and Technology (NIST) statistical tests

Novel reversible text data de-identification techniques based on native data structures

Technological development in today's digital world has resulted in the collection and storage of large amounts of personal data. These data enable both direct services and non-direct activities, known as secondary use. The secondary use of data can improve decision-making, service experiences, and healthcare systems. However, the widespread reuse of personal data raises significant privacy and policy issues, especially for health- related information; these data may contain sensitive data, leading to privacy breaches if compromised. Legal systems establish laws to protect the privacy of personal data disclosed for secondary use. A well-known example is the General Data Protection Regulation (GDPR), which outlines a specific set of rules for sharing and storing personal data to protect individual privacy. The GDPR explicitly points to data de-identification, especially pseudonymization, as one measure that can help meet the requirements for the processing of personal data. The literature on privacy preservation approaches has largely been developed in the field of data anonymization, where personal data are irreversibly removed or obfuscated and there is no means by which to recover an individual's identity if needed. By contrast, pseudonymization is a promising technique to protect privacy while enabling the recovery of de-identified data. Significantly, many existing approaches for pseudonymization were developed long before the GDPR requirements were established, and so they may fail to satisfy its provisions. Therefore, it is worthwhile to offer technical solutions to preserve privacy while supporting the legitimate use of data. This thesis proposes a novel de-identification system for unstructured textual data, known as ARTPHIL, that generates de-identified data in compliance with the GDPR requirement for strong pseudonymization. The system was evaluated using 2014 i2b2 testing data. The proposed system achieved a recall of 96.93% in terms of detecting and encrypting personal health information, as specified under guidelines provided by the Health Insurance Portability and Accountability Act (HIPAA). The system used a novel and lightweight cryptography algorithm E-ART to encrypt personal data cost-effectively and without compromising security. The main novelty of the E-ART algorithm is the use of the reflection property of a balanced binary tree data structure as substitution method instead of complex and multiple iterations. The performance and security of the proposed algorithm were compared to two symmetric encryption algorithms: The Advanced Encryption Standard and Data Encryption Standard. The security analysis showed comparable results, but the performance analysis indicated that E‐ART had the shortest ciphertext and running time with comparable memory usage, which indicates the feasibility of using ARTPHIL for delay-sensitive or data-intensive application

Cryptology: A didactical transposition into grade 10 school Mathematics classroom

Philosophiae Doctor - PhDThis study in an extension of a Master's study, entitled Realistic Mathematics Education and the strategies grade 8 learners develop for the solution of two simultaneous linear equations. the current study investigates how new content could be introduced into a school mathematical curriculum. The new topic under discussion for this study is the topis of Cryptology. Two research cycles were carried out. For the first design research cycle there were three teaching experiments with teachers, grade 10 learners and students as participants. Seven activities weere developed from the second design research cycle which was worked through with gade 10 learners. All sessions for the second design research cycle were video taped. Important to the development of instrutional materials was the development of a hypothetical learning trajetory about the learning and teaching of each activity. the results of the study indicated that the way learners understood the content and the different ways in which they presented solutions augers well for the introduction of a specific new content strand, cryptology, into a new school mathematical curriculum. It is also important for developers of instructional material to have a strong mathematical content knowledge for the design of instructional materialsSouth Afric

A Salad of Block Ciphers

This book is a survey on the state of the art in block cipher design and analysis. It is work in progress, and it has been for the good part of the last three years -- sadly, for various reasons no significant change has been made during the last twelve months. However, it is also in a self-contained, useable, and relatively polished state, and for this reason I have decided to release this \textit{snapshot} onto the public as a service to the cryptographic community, both in order to obtain feedback, and also as a means to give something back to the community from which I have learned much. At some point I will produce a final version -- whatever being a ``final version\u27\u27 means in the constantly evolving field of block cipher design -- and I will publish it. In the meantime I hope the material contained here will be useful to other people

Computer and data security: a comprehensive annotated bibliography.

Massachusetts Institute of Technology, Alfred P. Sloan School of Management. Thesis. 1973. M.S.MICROFICHE COPY ALSO AVAILABLE IN DEWEY LIBRARY.M.S

Towards a General Framework for Digital Rights Management (DRM)

Digital rights management (DRM) can be defined as a technology that enables persistent access control. The common understanding of DRM is that of a technology that enables means to thwart piracy of digital multimedia through limiting how the media is used by the consumer. It can be observed that many of these restrictions can be applied to any type of data. Therefore, it should be possible to create a two part DRM system -- a common DRM system that enforces the basic access controls (such as read, write and execute) and an application specific DRM system that enforces the application specific access controls (such as print and play). The aim of this dissertation is to create such a framework for distribution independent DRM systems. Most vendors promote DRM as a copyright protection mechanism, and thus consumers expect a number of rights that are allowed by copyright legislation, but which are not available for the DRM protected media. However, DRM is not an enforcement of copyright law, but rather an enforcement of a licensing regime. Thus, there is incorrect (and possibly false) marketing of DRM enabled media from the vendors of DRM enabled media, leading to dissatisfied consumers. We think that one of the main reasons for the current situation, is that there is no defined legal framework governing the operation of DRM systems. In this dissertation, we address this gap, by developing a legal framework for DRM systems as one of the components of our DRM framework. Negotiation can be defined as the process which leads to the conclusion of a contract. Since DRM is the enforcement of licensing agreements, there is a need to cater for negotiation protocols in DRM systems. Negotiations provide the consumer with the power to request different rights packages, especially when consumers have a legitimate need for rights not granted normally to other consumers (for example, disabled consumers have needs that may not be met with standard rights set). Negotiations also allow the possibility for the licensors to extract the maximum value from the consumers. For this reason, the inclusion of negotiation protocols in DRM systems can become a powerful tool, and in this dissertation we present the first negotiation protocols for DRM systems. Even though the definition of DRM as an access control model has existed since at least 2002, there has been no formal description of DRM as an access control model. Thus, there are no formal models for any of the rights expression languages which express DRM access control policies, and various authors have commented on ambiguities present in interpretation and enforcement of licenses expressed in these languages -- a result of a lack of formal definition of these languages. In this dissertation, we develop a formal model for a Licensing Rights Expression Language (LiREL), which is designed to provide a mechanism to express access control policies which are also sound legal license documents. Our formal model also discusses the enforcement of the access control policies, and is thus the first formal model for DRM as a mechanism for access control. Access control is a two part process: authentication of the parties involved and authorisation of the parties to access the resources. Authorisation in DRM provides some unique challenges: there is a need to support multiple platforms, without guaranteed network connectivity and minimal trust between the parties involved. For this reason, the associated authentication framework becomes more complex. While many access control models define user management as part of their model, we have taken a different approach, and removed user management from the core DRM system. Instead, our authorisation process requires a trusted verification of the user's credentials and then decides on the access control request. For this reason, our user authentication framework is ticket based, and shares similarities to Kerberos tickets. DRM also requires a strong data identity management. However, all the current identity systems for data do not provide verification service for data identity. For this reason, we developed Verifiable Digital Object Identity (VDOI) System, to address this gap. These components are combined towards a general framework for digital rights management that advances the understanding, organisation and implementation of DRM compared to approaches or solutions which are currently available