PRANAB CHAKRABORTY is Senior Manager at the Learning and Development team of Wipro Limited, Bengaluru, India. He earned his graduate degree in computer science from the Indian Statistical Institute, Kolkata, India, and undergraduate degree in electronics and telecommunications engineering from Jadavpur University, Kolkata, India. He has implemented various network protocol stacks including TCP/IP and played different organizational roles including that of a technical architect and technical delivery manager apart from his current involvement in the behavioral and leadership development field. He has a special interest in the research areas of cryptology.SUBHAMOY MAITRA is Senior Professor at the Applied Statistics Unit of the Indian Statistical Institute, Kolkata, India. He earned his Ph.D. and graduate degree in computer science from the Indian Statistical Institute, Kolkata, India, and undergraduate degree in electronics and telecommunications engineering from Jadavpur University, Kolkata, India. Post working in the domain of hardware and software engineering for a few years, Prof. Maitra joined the Indian Statistical Institute, Kolkata, as a faculty in 1997. Having around 6000 citations to his name, Prof. Maitra has authored several books and around 200 research papers in the area of cryptology and quantum information.MRIDUL NANDI is Professor at the Applied Statistics Unit of the Indian Statistical Institute, Kolkata, India. Earlier, he worked for the National Institute of Standards and Technology (NIST), USA, as one of the technical members in the selection process of the SHA3 hash function. His research areas focus on different aspects of cryptography, including hash functions, MAC, authenticated encryption, identity (or attribute) based encryption, IoT, hardware implementation and lightweight cryptography. He is the co-designer of COLM (authenticated encryption), selected as a winner in the security category of CAESAR portfolio. Algorithms ofhis designed 10 lightweight ciphers were selected for the second round of NIST lightweight standard process. He actively publishes papers in top tier conferences like Eurocrypt, Crypto, Asiacrypt, FSE and renowned journals.SUPRITA TALNIKAR is Senior Research Fellow at the Applied Statistics Unit of the Indian Statistical Institute, Kolkata, India. She is pursuing her Ph.D. in Computer Science, under the supervision of Prof. Mridul Nandi. She completed her M.Sc. in Mathematics from Visvesvaraya National Institute of Technology, Nagpur, India, with a gold medal, and her B.Sc. in Physics, Computer Science and Mathematics from Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, India. Her research focuses on various areas of cryptography, with particular interest in provable security and cryptanalysis in symmetric key cryptography.

• 1. Introduction and Preliminaries.- 2. Centralized Systems.- 3. Decentralized Contact Tracing Protocols.- 4. A New Contact Tracing Protocol.

PRANAB CHAKRABORTY is Senior Manager at the Learning and Development team of Wipro Limited, Bengaluru, India. He earned his graduate degree in computer science from the Indian Statistical Institute, Kolkata, India, and undergraduate degree in electronics and telecommunications engineering from Jadavpur University, Kolkata, India. He has implemented various network protocol stacks including TCP/IP and played different organizational roles including that of a technical architect and technical delivery manager apart from his current involvement in the behavioral and leadership development field. He has a special interest in the research areas of cryptology.SUBHAMOY MAITRA is Senior Professor at the Applied Statistics Unit of the Indian Statistical Institute, Kolkata, India. He earned his Ph.D. and graduate degree in computer science from the Indian Statistical Institute, Kolkata, India, and undergraduate degree in electronics and telecommunications engineering from Jadavpur University, Kolkata, India. Post working in the domain of hardware and software engineering for a few years, Prof. Maitra joined the Indian Statistical Institute, Kolkata, as a faculty in 1997. Having around 6000 citations to his name, Prof. Maitra has authored several books and around 200 research papers in the area of cryptology and quantum information.MRIDUL NANDI is Professor at the Applied Statistics Unit of the Indian Statistical Institute, Kolkata, India. Earlier, he worked for the National Institute of Standards and Technology (NIST), USA, as one of the technical members in the selection process of the SHA3 hash function. His research areas focus on different aspects of cryptography, including hash functions, MAC, authenticated encryption, identity (or attribute) based encryption, IoT, hardware implementation and lightweight cryptography. He is the co-designer of COLM (authenticated encryption), selected as a winner in the security category of CAESAR portfolio. Algorithms ofhis designed 10 lightweight ciphers were selected for the second round of NIST lightweight standard process. He actively publishes papers in top tier conferences like Eurocrypt, Crypto, Asiacrypt, FSE and renowned journals.SUPRITA TALNIKAR is Senior Research Fellow at the Applied Statistics Unit of the Indian Statistical Institute, Kolkata, India. She is pursuing her Ph.D. in Computer Science, under the supervision of Prof. Mridul Nandi. She completed her M.Sc. in Mathematics from Visvesvaraya National Institute of Technology, Nagpur, India, with a gold medal, and her B.Sc. in Physics, Computer Science and Mathematics from Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, India. Her research focuses on various areas of cryptography, with particular interest in provable security and cryptanalysis in symmetric key cryptography.

• 1. Introduction and Preliminaries.- 2. Centralized Systems.- 3. Decentralized Contact Tracing Protocols.- 4. A New Contact Tracing Protocol.

PRANAB CHAKRABORTY is Senior Manager at the Learning and Development team of Wipro Limited, Bengaluru, India. He earned his graduate degree in computer science from the Indian Statistical Institute, Kolkata, India, and undergraduate degree in electronics and telecommunications engineering from Jadavpur University, Kolkata, India. He has implemented various network protocol stacks including TCP/IP and played different organizational roles including that of a technical architect and technical delivery manager apart from his current involvement in the behavioral and leadership development field. He has a special interest in the research areas of cryptology.SUBHAMOY MAITRA is Senior Professor at the Applied Statistics Unit of the Indian Statistical Institute, Kolkata, India. He earned his Ph.D. and graduate degree in computer science from the Indian Statistical Institute, Kolkata, India, and undergraduate degree in electronics and telecommunications engineering from Jadavpur University, Kolkata, India. Post working in the domain of hardware and software engineering for a few years, Prof. Maitra joined the Indian Statistical Institute, Kolkata, as a faculty in 1997. Having around 6000 citations to his name, Prof. Maitra has authored several books and around 200 research papers in the area of cryptology and quantum information.MRIDUL NANDI is Professor at the Applied Statistics Unit of the Indian Statistical Institute, Kolkata, India. Earlier, he worked for the National Institute of Standards and Technology (NIST), USA, as one of the technical members in the selection process of the SHA3 hash function. His research areas focus on different aspects of cryptography, including hash functions, MAC, authenticated encryption, identity (or attribute) based encryption, IoT, hardware implementation and lightweight cryptography. He is the co-designer of COLM (authenticated encryption), selected as a winner in the security category of CAESAR portfolio. Algorithms ofhis designed 10 lightweight ciphers were selected for the second round of NIST lightweight standard process. He actively publishes papers in top tier conferences like Eurocrypt, Crypto, Asiacrypt, FSE and renowned journals.SUPRITA TALNIKAR is Senior Research Fellow at the Applied Statistics Unit of the Indian Statistical Institute, Kolkata, India. She is pursuing her Ph.D. in Computer Science, under the supervision of Prof. Mridul Nandi. She completed her M.Sc. in Mathematics from Visvesvaraya National Institute of Technology, Nagpur, India, with a gold medal, and her B.Sc. in Physics, Computer Science and Mathematics from Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, India. Her research focuses on various areas of cryptography, with particular interest in provable security and cryptanalysis in symmetric key cryptography.

• 1. Introduction and Preliminaries.- 2. Centralized Systems.- 3. Decentralized Contact Tracing Protocols.- 4. A New Contact Tracing Protocol.