41 results sorted by ID
Possible spell-corrected query: COVID-192
Privacy-Preserving Digital Vaccine Passport
Thai Duong, Jiahui Gao, Duong Hieu Phan, Ni Trieu
Applications
The global lockdown imposed during the Covid-19 pandemic has resulted in significant social and economic challenges. In an effort to reopen economies and simultaneously control the spread of the disease, the implementation of contact tracing and digital vaccine passport technologies has been introduced. While contact tracing methods have been extensively studied and scrutinized for security concerns through numerous publications, vaccine passports have not received the same level of...
Privacy-Preserving Outsourced Certificate Validation
Tarek Galal, Anja Lehmann
Cryptographic protocols
Digital Covid certificates are the first widely deployed end-user cryptographic certificates. For service providers, such as airlines or event ticket vendors, that needed to check that their (global) customers satisfy certain health policies, the verification of such Covid certificates was challenging though - not because of the cryptography involved, but due to the multitude of issuers, different certificate types and the evolving nature of country-specific policies that had to be...
To Pass or Not to Pass: Privacy-Preserving Physical Access Control
Jesús García-Rodríguez, Stephan Krenn, Daniel Slamanig
Cryptographic protocols
Anonymous or attribute-based credential (ABC) systems are a versatile and important cryptographic tool to achieve strong access control guarantees while simultaneously respecting the privacy of individuals. A major problem in the practical adoption of ABCs is their transferability, i.e., such credentials can easily be duplicated, shared or lent. One way to counter this problem is to tie ABCs to biometric features of the credential holder and to require biometric verification on every use....
Glass-Vault: A Generic Transparent Privacy-preserving Exposure Notification Analytics Platform
Lorenzo Martinico, Aydin Abadi, Thomas Zacharias, Thomas Win
Cryptographic protocols
The highly transmissible COVID-19 disease is a serious threat to people’s health and life. To automate tracing those who have been in close physical contact with newly infected people and/or to analyse tracing-related data, researchers have proposed various ad-hoc programs that require being executed on users’ smartphones. Nevertheless, the existing solutions have two primary limitations: (1) lack of generality: for each type of analytic task, a certain kind of data needs to be sent to an...
Blockchain based Contact Tracing: A Solution using Bluetooth and Sound Waves for Proximity Detection
ZiXi Hee, Iftekhar Salam
Applications
In the wake of the Covid-19 pandemic, countries and organizations started looking towards technology to curb the spread of the disease, for instance, conducting contact tracing with smartphones. Many contact tracing applications are on the market, built on different technology, such as Bluetooth, GPS, Sound, and QR code scanning systems. The use of sound is an area that has potential for further exploration; currently, only NOVID is utilizing this technology. On top of that, there is a need...
Digital Contact Tracing Solutions: Promises, Pitfalls and Challenges
Thien Duc Nguyen, Markus Miettinen, Alexandra Dmitrienko, Ahmad-Reza Sadeghi, Ivan Visconti
Applications
The COVID-19 pandemic has caused many countries to deploy novel digital contact tracing (DCT) systems to boost the efficiency of manual tracing of infection chains. In this paper, we systematically analyze DCT solutions and categorize them based on their design approaches and architectures. We analyze them with regard to effectiveness, security, privacy, and ethical aspects and compare prominent solutions with regard to these requirements. In particular, we discuss the shortcomings of the...
Circuit-based PSI for Covid-19 Risk Scoring
Leonie Reichert, Marcel Pazelt, Björn Scheuermann
Applications
—Many solutions have been proposed to improve manual contact tracing for infectious diseases through automation. Privacy is crucial for the deployment of such a system as it greatly influences adoption. Approaches for digital contact tracing like Google Apple Exposure Notification (GAEN) protect the privacy of users by decentralizing risk scoring. But GAEN leaks information about diagnosed users as ephemeral pseudonyms are broadcast to everyone. To combat deanonymisation based on the time of...
Generalized Proof of Liabilities
Yan Ji, Konstantinos Chalkias
Cryptographic protocols
Proof of liabilities (PoL) allows a prover to prove his/her liabilities to a group of verifiers. This is a cryptographic primitive once used only for proving financial solvency but is also applicable to domains outside finance, including transparent and private donations, new algorithms for disapproval voting and publicly verifiable official reports such as COVID-19 daily cases. These applications share a common nature in incentives: it's not in the prover's interest to increase his/her...
Privacy-preserving Density-based Clustering
Beyza Bozdemir, Sébastien Canard, Orhan Ermis, Helen Möllering, Melek Önen, Thomas Schneider
Applications
Clustering is an unsupervised machine learning technique that outputs clusters containing similar data items. In this work, we investigate privacy-preserving density-based clustering which is, for example, used in financial analytics and medical diagnosis. When (multiple) data owners collaborate or outsource the computation, privacy concerns arise.
To address this problem, we design, implement, and evaluate the first practical and fully private density-based clustering scheme based on secure...
Security Analysis of End-to-End Encryption for Zoom Meetings
Takanori Isobe, Ryoma Ito
Cryptographic protocols
In the wake of the global COVID-19 pandemic, video conference systems have become essential for not only business purposes, but also private, academic, and educational uses. Among the various systems, Zoom is the most widely deployed video conference system. In October 2020, Zoom Video Communications rolled out their end-to-end encryption (E2EE) to protect conversations in a meeting from even insiders, namely, the service provider Zoom. In this study, we conduct thorough security evaluations...
PSImple: Practical Multiparty Maliciously-Secure Private Set Intersection
Aner Ben Efraim, Olga Nissenbaum, Eran Omri, Anat Paskin-Cherniavsky
Cryptographic protocols
Private set intersection (PSI) protocols allow a set of mutually distrustful parties, each holding a private set of items,
to compute the intersection over all their sets, such that no other information is revealed.
PSI has a wide variety of applications including online advertising (e.g., efficacy computation), security (e.g., botnet detection, intrusion detection), proximity testing (e.g., COVID-19 contact tracing), and more. Private set intersection is a rapidly developing area and there...
Privacy-Preserving Epidemiological Modeling on Mobile Graphs
Daniel Günther, Marco Holz, Benjamin Judkewitz, Helen Möllering, Benny Pinkas, Thomas Schneider, Ajith Suresh
Applications
The latest pandemic COVID-19 brought governments worldwide to use various containment measures to control its spread, such as contact tracing, social distance regulations, and curfews. Epidemiological simulations are commonly used to assess the impact of those policies before they are implemented. Unfortunately, the scarcity of relevant empirical data, specifically detailed social contact graphs, hampered their predictive accuracy. As this data is inherently privacy-critical, a method is...
CovidBloc: A Blockchain Powered Exposure Database for Contact Tracing
Deepraj Pandey, Nandini Agrawal, Mahabir Prasad Jhanwar
Implementation
Contact tracing is an important mitigation tool for national health services to fight epidemics such as COVID-19. While many of the existing approaches for automated contact tracing focus on privacy-preserving decentralized solutions, the use of blockchain in these applications is often suggested for the transparency and immutability of the data being collected.
We present CovidBloc, a contact tracing system that implements the COVID 19 exposure database on Hyperledger Fabric Blockchain...
Automatic Privacy-Preserving Contact Tracing of Novel Coronavirus Infection by Cloud-Enabled WBAN using Blockchain
Anupam Pattanayak, Subhasish Dhal, Sourav Kanti Addya
Applications
Governments and policy makers are finding it difficult to curb the enormous spread of pandemic Covid-19 till the vaccine is invented and becomes available for use. When a person is detected to be infected with Novel coronavirus, the task of identifying the persons who have come across the victim in past fortnight is a challenging task. Identifying these contact persons manually is a hilarious task and often yields incomplete data. Some governments have used digital technology for contact...
Lighthouses: A Warning System for Super-Spreader Events
Leonie Reichert, Samuel Brack, Björn Scheuermann
Applications
Super-spreader events where one person infects many others have been a driving force of the Covid-19 pandemic.
Such events often happen indoors, such as in restaurants, at choir practice or in gyms.
Many systems for automated contact tracing (ACT) have been proposed, which will warn a user when they have been in proximity to an infected person.
These generally fail to detect potential super-spreader events as only users who have come in close contact with the infected person, but not others...
Ovid: Message-based Automatic Contact Tracing
Leonie Reichert, Samuel Brack, Björn Scheuermann
Applications
The Covid-19 pandemic created various new challenges for our societies.
Quickly discovering new infections using automated contact tracing without endangering privacy of the general public is one of these.
Most discussions concerning architectures for contact tracing applications revolved around centralized against decentralized approaches.
In contrast, the system proposed in this work builds on the idea of message-based contact tracing to inform users of their risk.
Our main contribution is...
On the Effectiveness of Time Travel to Inject COVID-19 Alerts
Vincenzo Iovino, Serge Vaudenay, Martin Vuagnoux
Applications
Digital contact tracing apps allow to alert people who have been in contact with people who may be contagious. The Google/Apple Exposure Notification (GAEN) system is based on Bluetooth proximity estimation. It has been adopted by many countries around the world. However, many possible attacks are known. The goal of some of them is to inject a false alert on someone else's phone. This way, an adversary can eliminate a competitor in a sport event or a business in general. Political parties...
Provable Security Analysis of Decentralized Cryptographic Contact Tracing
Noel Danz, Oliver Derwisch, Anja Lehmann, Wenzel Puenter, Marvin Stolle, Joshua Ziemann
Automated contact tracing leverages the ubiquity of smartphones to warn users about an increased exposure risk to COVID-19. In the course of only a few weeks, several cryptographic protocols have been proposed that aim to achieve such contract tracing in a decentralized and privacy-preserving way. Roughly, they let users' phones exchange random looking pseudonyms that are derived from locally stored keys. If a user is diagnosed, her phone uploads the keys which allows other users to check...
Secure Data Hiding for Contact Tracing
Craig Gotsman, Kai Hormann
Contact tracing is an effective tool in controlling the spread of infectious diseases such as COVID-19. It involves digital monitoring and recording of physical proximity between people over time with a central and trusted authority, so that when one user reports infection, it is possible to identify all other users who have been in close proximity to that person during a relevant time period in the past and alert them. One way to achieve this involves recording on the server the locations,...
HABIT: Hardware-Assisted Bluetooth-based Infection Tracking
Nathan Manohar, Peter Manohar, Rajit Manohar
Applications
The ongoing COVID-19 pandemic has caused health organizations to consider using digital contact tracing to help monitor and contain the spread of COVID-19. Due to this urgent need, many different groups have developed secure and private contact tracing phone apps. However, these apps have not been widely deployed, in part because they do not meet the needs of healthcare officials.
We present HABIT, a contact tracing system using a wearable hardware device designed specifically with the...
Privacy-Preserving Multi-Operator Contact Tracing for Early Detection of Covid19 Contagions
Davide Andreoletti, Omran Ayoub, Silvia Giordano, Massimo Tornatore, Giacomo Verticale
The outbreak of coronavirus disease 2019 (covid-19) is imposing a severe worldwide lock-down. Contact tracing based on smartphones' applications (apps) has emerged as a possible solution to trace contagions and enforce a more sustainable selective quarantine. However, a massive adoption of these apps is required to reach the critical mass needed for effective contact tracing. As an alternative, geo-location technologies in next generation networks (e.g., 5G) can enable Mobile Operators (MOs)...
Privacy-Preserving Automated Exposure Notification
Ran Canetti, Yael Tauman Kalai, Anna Lysyanskaya, Ronald L. Rivest, Adi Shamir, Emily Shen, Ari Trachtenberg, Mayank Varia, Daniel J. Weitzner
Applications
Contact tracing is an essential component of public health efforts to slow the spread of COVID-19 and other infectious diseases. Automating parts of the contact tracing process has the potential to significantly increase its scalability and efficacy, but also raises an array of privacy concerns, including the risk of unwanted identification of infected individuals and clandestine collection of privacy-invasive data about the population at large.
In this paper, we focus on automating the...
PHyCT : Privacy preserving Hybrid Contact Tracing
Mahabir Prasad Jhanwar, Sumanta Sarkar
Applications
Ever since COVID-19 started grasping world’s geographies one by one, countries have been struggling to tackle with this emergency by stretching their healthcare infrastructure beyond the boundary. World is now also trying to find ways to “live with the virus” or coping with the “new normal”. In this effort, contact tracing is thought to be a vital tool which can quickly
figure out persons that have come into vicinity of an infected person. Some countries have adopted centralized contact...
Trace-$\Sigma$: a privacy-preserving contact tracing app
Jean-François Biasse, Sriram Chellappan, Sherzod Kariev, Noyem Khan, Lynette Menezes, Efe Seyitoglu, Charurut Somboonwit, Attila Yavuz
Applications
We present a privacy-preserving protocol to anonymously collect information about
a social graph. The typical application of our protocol is Bluetooth-enabled ``contact-tracing apps''
which record information about proximity between users to infer the risk of propagation
of COVID-19 among them. The main contribution of this work is to enable a central
server to construct an anonymous graph of interactions between users. This graph
gives the central authority insight on the propagation of...
A Survey of Automatic Contact Tracing Approaches Using Bluetooth Low Energy
Leonie Reichert, Samuel Brack, Björn Scheuermann
Applications
To combat the ongoing Covid-19 pandemic, many new ways have been proposed on how to automate the process of finding infected people, also called contact tracing. A special focus was put on preserving the privacy of users. Bluetooth Low Energy (BLE) as base technology has the most promising properties, so this survey focuses on automated contact tracing techniques using BLE. We define multiple classes of methods and identify two major groups: systems that rely on a server for finding new...
Inverse-Sybil Attacks in Automated Contact Tracing
Benedikt Auerbach, Suvradip Chakraborty, Karen Klein, Guillermo Pascual-Perez, Krzysztof Pietrzak, Michael Walter, Michelle Yeo
Cryptographic protocols
Automated contract tracing aims at supporting manual contact tracing during pandemics by alerting users of encounters with infected people. There are currently many proposals for protocols (like the “decentralized” DP-3T and PACT or the “centralized” ROBERT and DESIRE) to be run on mobile phones, where the basic idea is to regularly broadcast (using low energy Bluetooth) some values, and at the same time store (a function of) incoming messages broadcasted by users in their proximity. In the...
ContactChaser: A Simple yet Effective Contact Tracing Scheme with Strong Privacy
Zhiguo Wan, Xiaotong Liu
Applications
The COVID-19 pandemic is a severe threat to both lives and economics throughout the world. Advanced information technology can play an important role to win this war against this invisible enemy. The most effective way to fight COVID-19 is quarantining infected people and identifying their contacts. Recently, quite a few Bluetooth-based contact tracing proposals have been proposed to identify who has come into contact with infected people. The success of a contact tracing system depends on...
Component-Based Comparison of Privacy-First Exposure Notification Protocols
Ellie Daw
Applications
Various privacy-preserving protocols for exposure notification have been developed across the globe in order to aid in scaling contact tracing efforts during the COVID-19 crisis, a strategy proven to be critical in effectively slowing the spread of infectious disease. Although having a multitude of people working toward a similar goal creates momentum and aids in quality refinement, it also causes confusion for entities hoping to adopt one protocol for application development. This paper...
Risk and Architecture factors in Digital Exposure Notification
Archanaa S. Krishnan, Yaling Yang, Patrick Schaumont
Applications
To effectively trace the infection spread in a pandemic, a large number of manual contact tracers are required to reach out to all possible contacts of infected users. Exposure notification, a.k.a. digital contact tracing, can supplement manual contact tracing to ease the burden on manual tracers and to digitally obtain accurate contact information. We review the state-of-the-art solutions that offer security and privacy-friendly design. We study the role of policies and decision making to...
Centralized or Decentralized? The Contact Tracing Dilemma
Serge Vaudenay
Applications
The COVID-19 pandemic created a noticeable challenge to the cryptographic community with the development of contact tracing applications. The media reported a dispute between designers proposing a centralized or a decentralized solution (namely, the PEPP-PT and the DP3T projects). Perhaps, the time constraints to develop and deploy efficient solutions led to non-optimal (in terms of privacy) solutions. Moreover, arguments have been severely biased and the scientific debate did not really...
Privacy-Preserving COVID-19 Contact Tracing App: A Zero-Knowledge Proof Approach
Joseph K. Liu, Man Ho Au, Tsz Hon Yuen, Cong Zuo, Jiawei Wang, Amin Sakzad, Xiapu Luo, Li Li, Kim-Kwang Raymond Choo
Applications
In this paper, we propose a privacy-preserving contact tracing protocol for smart phones, and more specifically Android and iOS phones. The protocol allows users to be notified, if they have been a close contact of a confirmed patient. The protocol is designed to strike a balance between privacy, security, and scalability. Specifically, the app allows all users to hide their past location(s) and contact history from the Government, without affecting their ability to determine whether they...
Privately Connecting Mobility to Infectious Diseases via Applied Cryptography
Alexandros Bampoulidis, Alessandro Bruni, Lukas Helminger, Daniel Kales, Christian Rechberger, Roman Walch
Cryptographic protocols
Recent work has shown that cell phone mobility data has the unique potential to create accurate models for human mobility and consequently the spread of infected diseases. While prior studies have exclusively relied on a mobile network operator's subscribers' aggregated data in modelling disease dynamics, it may be preferable to contemplate aggregated mobility data of infected individuals only. Clearly, naively linking mobile phone data with health records would violate privacy by either...
Towards Defeating Mass Surveillance and SARS-CoV-2: The Pronto-C2 Fully Decentralized Automatic Contact Tracing System
Gennaro Avitabile, Vincenzo Botta, Vincenzo Iovino, Ivan Visconti
Cryptographic protocols
Mass surveillance can be more easily achieved leveraging fear and desire of the population to feel protected while affected by devastating events. Indeed, in such scenarios, governments can adopt exceptional measures that limit civil rights, usually receiving large support from citizens.
The COVID-19 pandemic is currently affecting daily life of many citizens in the world. People are forced to stay home for several weeks, unemployment rates quickly increase, uncertainty and sadness...
Applicability of Mobile Contact Tracing in Fighting Pandemic (COVID-19): Issues, Challenges and Solutions
Aaqib Bashir Dar, Auqib Hamid Lone, Saniya Zahoor, Afshan Amin Khan, Roohie Naaz
Applications
Contact Tracing is considered as the first and the most effective step towards containing
an outbreak, as resources for mass testing and large quantity of vaccines are highly unlikely
available for immediate utilization. Effective contact tracing can allow societies
to reopen from lock-down even before availability of vaccines. The objective of mobile
contact tracing is to speed up the manual interview based contact tracing process for
containing an outbreak efficiently and quickly. In this...
Distributed Auditing Proofs of Liabilities
Konstantinos Chalkias, Kevin Lewi, Payman Mohassel, Valeria Nikolaenko
Cryptographic protocols
Distributed Auditing Proofs of Liabilities (DAPOL) provides a novel zero knowledge proof solution to a particular class of auditing cases, in which we assume that the audited entity does not have any incentive to increase its liabilities or obligations. There are numerous domains requiring such an auditing feature, including proving financial solvency, transparent fundraising campaigns and accurate lottery jackpot amounts. Additionally, the algorithm provides a solution to official reports,...
Security Analysis of the COVID-19 Contact Tracing Specifications by Apple Inc. and Google Inc.
Yaron Gvili
Applications
In a joint effort to fight the COVID-19 pandemic, Apple Inc. and Google Inc. recently partnered to develop a contact tracing technology, inspired by the DP-3T and TCN protocols, to help governments and health agencies reduce the spread of the virus, with user privacy and security central to the design. The partnership announcement included technical specifications of the planned technology, which has great potential for widespread adoption due to the global reach of the two companies. At the...
Privacy-Preserving Contact Tracing: current solutions and open questions
Qiang Tang
Applications
The COVID-19 pandemic has posed a unique challenge for the world to find solutions, ranging from vaccines to ICT solutions to slow down the virus spreading. Due to the highly contagious nature of the virus, social distancing is one fundamental measure which has already adopted by many countries. At the technical level, this prioritises contact tracing solutions, which can alert the users who have been in close contact with the infected persons and meanwhile allow heath authorities to take...
Delayed Authentication: Preventing Replay and Relay Attacks in Private Contact Tracing
Krzysztof Pietrzak
Applications
Currently several projects (including DP-3T, east and west coast PACT, Covid watch) aim at designing and implementing protocols for privacy preserving automated contact tracing to help fight the current pandemic. Those proposal are very similar, and in their most basic from basically propose an app for mobile phones which broadcasts frequently changing pseudorandom identifiers via (low energy) Bluetooth, and at the same time, the app stores IDs broadcast by phones in its proximity. Only if...
Analysis of DP3T
Serge Vaudenay
Applications
To help fighting the COVID-19 pandemic, the Pan-European Privacy-Preserving Proximity Tracing (PEPP-PT) project proposed a Decentralized Privacy-Preserving Proximity Tracing (DP3T) system. This helps tracking the spread of SARS-CoV-2 virus while keeping the privacy of individuals safe. In this report, we analyze the security and the privacy protection of DP3T. Without questioning how effective it could be against the pandemic, we show that it may introduce severe risks to society....
CAUDHT: Decentralized Contact Tracing Using a DHT and Blind Signatures
Samuel Brack, Leonie Reichert, Björn Scheuermann
Applications
Contact tracing is a promising approach to combat the COVID-19 pandemic. Various systems have been proposed to
automatise the process. Many designs rely heavily on a centralised server or reveal significant amounts of private data to health authorities. We propose CAUDHT, a decentralized peer-to-peer system for contact tracing. The central health authority can focus on providing and operating tests for the disease while contact tracing is done by the system’s users themselves. We use a...
Privacy-Preserving Contact Tracing of COVID-19 Patients
Leonie Reichert, Samuel Brack, Björn Scheuermann
Applications
The current Covid-19 pandemic shows that our modern globalized world can be heavily affected by a quickly spreading, highly infectious, deadly virus in a matter of weeks. It became apparent that manual contact tracing and quarantining of suspects can only be effective in the first days of the spread before the exponential growth overwhelms the health authorities. By automating tracing processes and quarantining everyone who came in contact with infected ...
The global lockdown imposed during the Covid-19 pandemic has resulted in significant social and economic challenges. In an effort to reopen economies and simultaneously control the spread of the disease, the implementation of contact tracing and digital vaccine passport technologies has been introduced. While contact tracing methods have been extensively studied and scrutinized for security concerns through numerous publications, vaccine passports have not received the same level of...
Digital Covid certificates are the first widely deployed end-user cryptographic certificates. For service providers, such as airlines or event ticket vendors, that needed to check that their (global) customers satisfy certain health policies, the verification of such Covid certificates was challenging though - not because of the cryptography involved, but due to the multitude of issuers, different certificate types and the evolving nature of country-specific policies that had to be...
Anonymous or attribute-based credential (ABC) systems are a versatile and important cryptographic tool to achieve strong access control guarantees while simultaneously respecting the privacy of individuals. A major problem in the practical adoption of ABCs is their transferability, i.e., such credentials can easily be duplicated, shared or lent. One way to counter this problem is to tie ABCs to biometric features of the credential holder and to require biometric verification on every use....
The highly transmissible COVID-19 disease is a serious threat to people’s health and life. To automate tracing those who have been in close physical contact with newly infected people and/or to analyse tracing-related data, researchers have proposed various ad-hoc programs that require being executed on users’ smartphones. Nevertheless, the existing solutions have two primary limitations: (1) lack of generality: for each type of analytic task, a certain kind of data needs to be sent to an...
In the wake of the Covid-19 pandemic, countries and organizations started looking towards technology to curb the spread of the disease, for instance, conducting contact tracing with smartphones. Many contact tracing applications are on the market, built on different technology, such as Bluetooth, GPS, Sound, and QR code scanning systems. The use of sound is an area that has potential for further exploration; currently, only NOVID is utilizing this technology. On top of that, there is a need...
The COVID-19 pandemic has caused many countries to deploy novel digital contact tracing (DCT) systems to boost the efficiency of manual tracing of infection chains. In this paper, we systematically analyze DCT solutions and categorize them based on their design approaches and architectures. We analyze them with regard to effectiveness, security, privacy, and ethical aspects and compare prominent solutions with regard to these requirements. In particular, we discuss the shortcomings of the...
—Many solutions have been proposed to improve manual contact tracing for infectious diseases through automation. Privacy is crucial for the deployment of such a system as it greatly influences adoption. Approaches for digital contact tracing like Google Apple Exposure Notification (GAEN) protect the privacy of users by decentralizing risk scoring. But GAEN leaks information about diagnosed users as ephemeral pseudonyms are broadcast to everyone. To combat deanonymisation based on the time of...
Proof of liabilities (PoL) allows a prover to prove his/her liabilities to a group of verifiers. This is a cryptographic primitive once used only for proving financial solvency but is also applicable to domains outside finance, including transparent and private donations, new algorithms for disapproval voting and publicly verifiable official reports such as COVID-19 daily cases. These applications share a common nature in incentives: it's not in the prover's interest to increase his/her...
Clustering is an unsupervised machine learning technique that outputs clusters containing similar data items. In this work, we investigate privacy-preserving density-based clustering which is, for example, used in financial analytics and medical diagnosis. When (multiple) data owners collaborate or outsource the computation, privacy concerns arise. To address this problem, we design, implement, and evaluate the first practical and fully private density-based clustering scheme based on secure...
In the wake of the global COVID-19 pandemic, video conference systems have become essential for not only business purposes, but also private, academic, and educational uses. Among the various systems, Zoom is the most widely deployed video conference system. In October 2020, Zoom Video Communications rolled out their end-to-end encryption (E2EE) to protect conversations in a meeting from even insiders, namely, the service provider Zoom. In this study, we conduct thorough security evaluations...
Private set intersection (PSI) protocols allow a set of mutually distrustful parties, each holding a private set of items, to compute the intersection over all their sets, such that no other information is revealed. PSI has a wide variety of applications including online advertising (e.g., efficacy computation), security (e.g., botnet detection, intrusion detection), proximity testing (e.g., COVID-19 contact tracing), and more. Private set intersection is a rapidly developing area and there...
The latest pandemic COVID-19 brought governments worldwide to use various containment measures to control its spread, such as contact tracing, social distance regulations, and curfews. Epidemiological simulations are commonly used to assess the impact of those policies before they are implemented. Unfortunately, the scarcity of relevant empirical data, specifically detailed social contact graphs, hampered their predictive accuracy. As this data is inherently privacy-critical, a method is...
Contact tracing is an important mitigation tool for national health services to fight epidemics such as COVID-19. While many of the existing approaches for automated contact tracing focus on privacy-preserving decentralized solutions, the use of blockchain in these applications is often suggested for the transparency and immutability of the data being collected. We present CovidBloc, a contact tracing system that implements the COVID 19 exposure database on Hyperledger Fabric Blockchain...
Governments and policy makers are finding it difficult to curb the enormous spread of pandemic Covid-19 till the vaccine is invented and becomes available for use. When a person is detected to be infected with Novel coronavirus, the task of identifying the persons who have come across the victim in past fortnight is a challenging task. Identifying these contact persons manually is a hilarious task and often yields incomplete data. Some governments have used digital technology for contact...
Super-spreader events where one person infects many others have been a driving force of the Covid-19 pandemic. Such events often happen indoors, such as in restaurants, at choir practice or in gyms. Many systems for automated contact tracing (ACT) have been proposed, which will warn a user when they have been in proximity to an infected person. These generally fail to detect potential super-spreader events as only users who have come in close contact with the infected person, but not others...
The Covid-19 pandemic created various new challenges for our societies. Quickly discovering new infections using automated contact tracing without endangering privacy of the general public is one of these. Most discussions concerning architectures for contact tracing applications revolved around centralized against decentralized approaches. In contrast, the system proposed in this work builds on the idea of message-based contact tracing to inform users of their risk. Our main contribution is...
Digital contact tracing apps allow to alert people who have been in contact with people who may be contagious. The Google/Apple Exposure Notification (GAEN) system is based on Bluetooth proximity estimation. It has been adopted by many countries around the world. However, many possible attacks are known. The goal of some of them is to inject a false alert on someone else's phone. This way, an adversary can eliminate a competitor in a sport event or a business in general. Political parties...
Automated contact tracing leverages the ubiquity of smartphones to warn users about an increased exposure risk to COVID-19. In the course of only a few weeks, several cryptographic protocols have been proposed that aim to achieve such contract tracing in a decentralized and privacy-preserving way. Roughly, they let users' phones exchange random looking pseudonyms that are derived from locally stored keys. If a user is diagnosed, her phone uploads the keys which allows other users to check...
Contact tracing is an effective tool in controlling the spread of infectious diseases such as COVID-19. It involves digital monitoring and recording of physical proximity between people over time with a central and trusted authority, so that when one user reports infection, it is possible to identify all other users who have been in close proximity to that person during a relevant time period in the past and alert them. One way to achieve this involves recording on the server the locations,...
The ongoing COVID-19 pandemic has caused health organizations to consider using digital contact tracing to help monitor and contain the spread of COVID-19. Due to this urgent need, many different groups have developed secure and private contact tracing phone apps. However, these apps have not been widely deployed, in part because they do not meet the needs of healthcare officials. We present HABIT, a contact tracing system using a wearable hardware device designed specifically with the...
The outbreak of coronavirus disease 2019 (covid-19) is imposing a severe worldwide lock-down. Contact tracing based on smartphones' applications (apps) has emerged as a possible solution to trace contagions and enforce a more sustainable selective quarantine. However, a massive adoption of these apps is required to reach the critical mass needed for effective contact tracing. As an alternative, geo-location technologies in next generation networks (e.g., 5G) can enable Mobile Operators (MOs)...
Contact tracing is an essential component of public health efforts to slow the spread of COVID-19 and other infectious diseases. Automating parts of the contact tracing process has the potential to significantly increase its scalability and efficacy, but also raises an array of privacy concerns, including the risk of unwanted identification of infected individuals and clandestine collection of privacy-invasive data about the population at large. In this paper, we focus on automating the...
Ever since COVID-19 started grasping world’s geographies one by one, countries have been struggling to tackle with this emergency by stretching their healthcare infrastructure beyond the boundary. World is now also trying to find ways to “live with the virus” or coping with the “new normal”. In this effort, contact tracing is thought to be a vital tool which can quickly figure out persons that have come into vicinity of an infected person. Some countries have adopted centralized contact...
We present a privacy-preserving protocol to anonymously collect information about a social graph. The typical application of our protocol is Bluetooth-enabled ``contact-tracing apps'' which record information about proximity between users to infer the risk of propagation of COVID-19 among them. The main contribution of this work is to enable a central server to construct an anonymous graph of interactions between users. This graph gives the central authority insight on the propagation of...
To combat the ongoing Covid-19 pandemic, many new ways have been proposed on how to automate the process of finding infected people, also called contact tracing. A special focus was put on preserving the privacy of users. Bluetooth Low Energy (BLE) as base technology has the most promising properties, so this survey focuses on automated contact tracing techniques using BLE. We define multiple classes of methods and identify two major groups: systems that rely on a server for finding new...
Automated contract tracing aims at supporting manual contact tracing during pandemics by alerting users of encounters with infected people. There are currently many proposals for protocols (like the “decentralized” DP-3T and PACT or the “centralized” ROBERT and DESIRE) to be run on mobile phones, where the basic idea is to regularly broadcast (using low energy Bluetooth) some values, and at the same time store (a function of) incoming messages broadcasted by users in their proximity. In the...
The COVID-19 pandemic is a severe threat to both lives and economics throughout the world. Advanced information technology can play an important role to win this war against this invisible enemy. The most effective way to fight COVID-19 is quarantining infected people and identifying their contacts. Recently, quite a few Bluetooth-based contact tracing proposals have been proposed to identify who has come into contact with infected people. The success of a contact tracing system depends on...
Various privacy-preserving protocols for exposure notification have been developed across the globe in order to aid in scaling contact tracing efforts during the COVID-19 crisis, a strategy proven to be critical in effectively slowing the spread of infectious disease. Although having a multitude of people working toward a similar goal creates momentum and aids in quality refinement, it also causes confusion for entities hoping to adopt one protocol for application development. This paper...
To effectively trace the infection spread in a pandemic, a large number of manual contact tracers are required to reach out to all possible contacts of infected users. Exposure notification, a.k.a. digital contact tracing, can supplement manual contact tracing to ease the burden on manual tracers and to digitally obtain accurate contact information. We review the state-of-the-art solutions that offer security and privacy-friendly design. We study the role of policies and decision making to...
The COVID-19 pandemic created a noticeable challenge to the cryptographic community with the development of contact tracing applications. The media reported a dispute between designers proposing a centralized or a decentralized solution (namely, the PEPP-PT and the DP3T projects). Perhaps, the time constraints to develop and deploy efficient solutions led to non-optimal (in terms of privacy) solutions. Moreover, arguments have been severely biased and the scientific debate did not really...
In this paper, we propose a privacy-preserving contact tracing protocol for smart phones, and more specifically Android and iOS phones. The protocol allows users to be notified, if they have been a close contact of a confirmed patient. The protocol is designed to strike a balance between privacy, security, and scalability. Specifically, the app allows all users to hide their past location(s) and contact history from the Government, without affecting their ability to determine whether they...
Recent work has shown that cell phone mobility data has the unique potential to create accurate models for human mobility and consequently the spread of infected diseases. While prior studies have exclusively relied on a mobile network operator's subscribers' aggregated data in modelling disease dynamics, it may be preferable to contemplate aggregated mobility data of infected individuals only. Clearly, naively linking mobile phone data with health records would violate privacy by either...
Mass surveillance can be more easily achieved leveraging fear and desire of the population to feel protected while affected by devastating events. Indeed, in such scenarios, governments can adopt exceptional measures that limit civil rights, usually receiving large support from citizens. The COVID-19 pandemic is currently affecting daily life of many citizens in the world. People are forced to stay home for several weeks, unemployment rates quickly increase, uncertainty and sadness...
Contact Tracing is considered as the first and the most effective step towards containing an outbreak, as resources for mass testing and large quantity of vaccines are highly unlikely available for immediate utilization. Effective contact tracing can allow societies to reopen from lock-down even before availability of vaccines. The objective of mobile contact tracing is to speed up the manual interview based contact tracing process for containing an outbreak efficiently and quickly. In this...
Distributed Auditing Proofs of Liabilities (DAPOL) provides a novel zero knowledge proof solution to a particular class of auditing cases, in which we assume that the audited entity does not have any incentive to increase its liabilities or obligations. There are numerous domains requiring such an auditing feature, including proving financial solvency, transparent fundraising campaigns and accurate lottery jackpot amounts. Additionally, the algorithm provides a solution to official reports,...
In a joint effort to fight the COVID-19 pandemic, Apple Inc. and Google Inc. recently partnered to develop a contact tracing technology, inspired by the DP-3T and TCN protocols, to help governments and health agencies reduce the spread of the virus, with user privacy and security central to the design. The partnership announcement included technical specifications of the planned technology, which has great potential for widespread adoption due to the global reach of the two companies. At the...
The COVID-19 pandemic has posed a unique challenge for the world to find solutions, ranging from vaccines to ICT solutions to slow down the virus spreading. Due to the highly contagious nature of the virus, social distancing is one fundamental measure which has already adopted by many countries. At the technical level, this prioritises contact tracing solutions, which can alert the users who have been in close contact with the infected persons and meanwhile allow heath authorities to take...
Currently several projects (including DP-3T, east and west coast PACT, Covid watch) aim at designing and implementing protocols for privacy preserving automated contact tracing to help fight the current pandemic. Those proposal are very similar, and in their most basic from basically propose an app for mobile phones which broadcasts frequently changing pseudorandom identifiers via (low energy) Bluetooth, and at the same time, the app stores IDs broadcast by phones in its proximity. Only if...
To help fighting the COVID-19 pandemic, the Pan-European Privacy-Preserving Proximity Tracing (PEPP-PT) project proposed a Decentralized Privacy-Preserving Proximity Tracing (DP3T) system. This helps tracking the spread of SARS-CoV-2 virus while keeping the privacy of individuals safe. In this report, we analyze the security and the privacy protection of DP3T. Without questioning how effective it could be against the pandemic, we show that it may introduce severe risks to society....
Contact tracing is a promising approach to combat the COVID-19 pandemic. Various systems have been proposed to automatise the process. Many designs rely heavily on a centralised server or reveal significant amounts of private data to health authorities. We propose CAUDHT, a decentralized peer-to-peer system for contact tracing. The central health authority can focus on providing and operating tests for the disease while contact tracing is done by the system’s users themselves. We use a...
The current Covid-19 pandemic shows that our modern globalized world can be heavily affected by a quickly spreading, highly infectious, deadly virus in a matter of weeks. It became apparent that manual contact tracing and quarantining of suspects can only be effective in the first days of the spread before the exponential growth overwhelms the health authorities. By automating tracing processes and quarantining everyone who came in contact with infected ...
