This book is a timely document of state-of-the-art techniques in the domain of contact tracing applications. Well known in the field of medical science, this topic has recently received attention from governments, industries and academic communities due to the COVID-19 pandemic. This book provides a link between new proposals related to contact tracing applications and a contextual literature review primarily from the cryptologic viewpoint. As these applications are related to security and privacy of individuals, analyzing them from cryptologic viewpoint is of utmost importance. Therefore, present developments from cryptologic aspects of most proposals around the world, including Singapore, Europe, USA, Australia and India, have been discussed. Providing an in-depth study on the design rationale of each protocol, this book is of value to researchers, students and professionals alike.

RC4 Stream Cipher and Its Variants is the first book to fully cover the popular software stream cipher RC4. With extensive expertise in stream cipher cryptanalysis and RC4 research, the authors focus on the analysis and design issues of RC4. They also explore variants of RC4 and the eSTREAM finalist HC-128. After an introduction to the vast field of cryptology, the book reviews hardware and software stream ciphers and describes RC4. It presents a theoretical analysis of RC4 KSA, discussing biases of the permutation bytes toward secret key bytes and absolute values. The text explains how to reconstruct the secret key from known state information and analyzes the RC4 PRGA in detail, including a sketch of state recovery attacks. The book then describes three popular attacks on RC4: distinguishing attacks, Wired Equivalent Privacy (WEP) protocol attacks, and fault attacks. The authors also compare the advantages and disadvantages of several variants of RC4 and examine stream cipher HC-128, which is the next level of evolution after RC4 in the software stream cipher paradigm. The final chapter emphasizes the safe use of RC4. With open research problems in each chapter, this book offers a complete account of the most current research on RC4.

This book is a timely document of state-of-the-art techniques in the domain of contact tracing applications. Well known in the field of medical science, this topic has recently received attention from governments, industries and academic communities due to the COVID-19 pandemic. This book provides a link between new proposals related to contact tracing applications and a contextual literature review primarily from the cryptologic viewpoint. As these applications are related to security and privacy of individuals, analyzing them from cryptologic viewpoint is of utmost importance. Therefore, present developments from cryptologic aspects of most proposals around the world, including Singapore, Europe, USA, Australia and India, have been discussed. Providing an in-depth study on the design rationale of each protocol, this book is of value to researchers, students and professionals alike.

Indocrypt began in the year 2000 under the leadership of Bimal Roy and - docrypt 2005 was the sixth conference in this series. This series has been well accepted by the international research community as a forum for presenting high-quality cryptography research. This year a total of 148 papers were s- mitted for consideration to the Program Committee and after a careful review process, 31 were accepted for presentation. We would like to thank the authors of all submitted papers, including those that were accepted and those which, unfortunately, could not be accommodated. ThereviewingprocessforIndocryptwasverystringentandtheschedulewas- tremelytight.TheProgramCommitteemembersdidanexcellentjobinreviewing andselectingthepapersforpresentation.Duringthereviewprocess, theProgram Committee members were communicating using a review software developed by BartPreneel, WimMoreauandJorisClaessens.Weacknowledgethemforprov- ingthesoftware.ThesoftwarewashostedatI2R, Singaporeandwearegratefulto Feng BaoandJianyingZhouforallowingthat.Thisyear'sconferencewasdeeply indebtedto QiuYingofI2R, Singapore, who tookthe responsibilityofmainta- ing the review softwareand the server.Without his great cooperationIndocrypt 2005could nothavebeen possible.Inthis regardI wouldliketo acknowledgethe supportofTanmoyKantiDas, DibyenduChakrabarti, MridulNandi, Deepak- mar Dalai, Sumanta Sarkar and Sourav Mukhopadhyay for handling important administrativeissuesinthesubmissionandreviewprocessesaswellasforputting togethertheseproceedingsintheir?nalform.WearealsogratefultoPalashSarkar forhiscooperationandguidanceinIndocrypt2005. The proceedings include the revised versions of the 31 selected papers. Re- sions were not checked by the ProgramCommittee and the authors bear the full responsibility for the contents of the respective papers. Our thanks go to all the Program members and the external reviewers (a list of them is included in the proceedings) who put in their valuable time and e?ort in providing important feedbackto the authors.We thank V. KumarMurty ofthe UniversityofToronto for kindly agreeing to present the invited talk. The talk has been included in the proceedin

TheINDOCRYPTconferenceseriesstartedin2000, andINDOCRYPT2003was the fourth one in this series. This series has been accepted by the international research community as a forum for presenting high-quality crypto research, as is evident from the 101 submissions this year, spread over 21 countries and all ?ve continents. The accepted papers were written by authors from 16 countries, covering four continents. A total of 101 papers were submitted for consideration to the program c- mittee, and after a careful reviewing process 30 were accepted for presentation. One of the conditionally accepted papers was withdrawn by the authors as they found an errorin the paper that could not be repairedin the short time between the noti?cation of the reviewand the ?nalversionsubmission.Thus the ?nal list contains29acceptedpapers.Wewouldliketo thanktheauthorsofallsubmitted papers, including both those that wereaccepted and those which, unfortunately, could not be accommodated. The reviewing process for INDOCRYPT was very stringent and the schedule was extremely tight. The program committee members did an excellent job in reviewing and selecting the papers for presentation. During the review process, theprogramcommitteememberscommunicatedusingareviewsoftwarepackage developed by Bart Preneel, Wim Moreau and Joris Claessens. We acknowledge them for providing this software. These proceedings include the revised versions of the 29 selected papers. Revisions were not checkedby the programcommittee and the authors bear the full responsibility for the contents of the respective papers. Our thanks go to all the program committee members and the external reviewers(alistofthem isincludedintheproceedings)whoputintheirvaluable time and e?ort in providing important feedback to the authors

RC4 Stream Cipher and Its Variants is the first book to fully cover the popular software stream cipher RC4. With extensive expertise in stream cipher cryptanalysis and RC4 research, the authors focus on the analysis and design issues of RC4. They also explore variants of RC4 and the eSTREAM finalist HC-128. After an introduction to the vast field of cryptology, the book reviews hardware and software stream ciphers and describes RC4. It presents a theoretical analysis of RC4 KSA, discussing biases of the permutation bytes toward secret key bytes and absolute values. The text explains how to reconstruct the secret key from known state information and analyzes the RC4 PRGA in detail, including a sketch of state recovery attacks. The book then describes three popular attacks on RC4: distinguishing attacks, Wired Equivalent Privacy (WEP) protocol attacks, and fault attacks. The authors also compare the advantages and disadvantages of several variants of RC4 and examine stream cipher HC-128, which is the next level of evolution after RC4 in the software stream cipher paradigm. The final chapter emphasizes the safe use of RC4. With open research problems in each chapter, this book offers a complete account of the most current research on RC4.

This book is a timely report of the state-of-the-art analytical techniques in the domain of quantum algorithms related to Boolean functions. It bridges the gap between recent developments in the area and the hands-on analysis of the spectral properties of Boolean functions from a cryptologic viewpoint. Topics covered in the book include Qubit, Deutsch-Jozsa and Walsh spectrum, Grover's algorithm, Simon's algorithm and autocorrelation spectrum. The book aims at encouraging readers to design and implement practical algorithms related to Boolean functions. Apart from combinatorial techniques, this book considers implementing related programs in a quantum computer. Researchers, practitioners and educators will find this book valuable.

This book is a timely document of state-of-the art analytical techniques in the domain of stream cipher design and analysis with a specific cipher, named ZUC. It links new research to brief contextual literature review in the domain of complex LFSR-based stream ciphers. A snapshot of how stream ciphers are deployed in the mobile telephony architecture, one of the most well-known topics for more than five decades in the domain of computer and communication sciences, is presented in this book. The book provides an in-depth study on design and cryptanalysis of ZUC as well as relevant research results in this field with directions towards future analysis of this cipher.