Joint Statement on Contact Tracing: Date 19th April 2020

The undersigned represent scientists and researchers from across the globe. The current COVID-19 crisis is unprecedented and we need innovative ways of coming out of the current lockdowns. However, we are concerned that some “solutions” to the crisis may, via mission creep, result in systems which would allow unprecedented surveillance of society at large.

Contact tracing is a well-understood tool to tackle epidemics, and has traditionally been done manually. However, manual contact tracing is time-consuming and is limited to people who can be identified.

In some situations, so-called “contact tracing Apps” on peoples’ smartphones may improve the effectiveness of the manual contact tracing technique. These Apps would allow the persons with whom an infected person had physical interaction to be notified, thus enabling them to go into quarantine. The Apps would work by using Bluetooth or geolocation data present in smartphones. Though the effectiveness of contact tracing Apps is controversial, we need to ensure that those implemented preserve the privacy of their users, thus safeguarding against many other issues, noting that such Apps can otherwise be repurposed to enable unwarranted discrimination and surveillance.

Research has demonstrated that solutions based on sharing geolocation (i.e., GPS) to discover contacts lack sufficient accuracy and also carry privacy risks because the GPS data is sent to a centralised location. For this reason, Bluetooth-based solutions for automated contact tracing are strongly preferred when available.

Some of the Bluetooth-based proposals respect the individual’s right to privacy, whilst others would enable (via mission creep) a form of government or private sector surveillance that would catastrophically hamper trust in and acceptance of such an application by society at large. It is crucial that citizens trust the applications in order to produce sufficient uptake to make a difference in tackling the crisis. It is vital that, in coming out of the current crisis, we do not create a tool that enables large scale data collection on the population, either now or at a later time. Thus, solutions which allow reconstructing invasive information about the population should be rejected without further discussion. Such information can include the ‘social graph’ of who someone has physically met over a period of time.

With access to the social graph, a bad actor (state, private sector, or hacker) could spy on citizens’ real-world activities. Some countries are seeking to build systems which could enable them to access and process this social graph. On the other hand, highly decentralised systems have no distinct entity that can learn anything about the social graph. In such systems, matching between users who have the disease and those who do not is performed on the non-infected users’ phones as anonymously as possible, whilst information about non-infected users is not revealed at all.

To aid the development of contact tracing without a centrally controlled database that holds private information on individuals, Google and Apple are developing infrastructure to enable the required Bluetooth operations in a privacy protective manner. Teams building the privacy protective schemes fully support this effort as it simplifies—and thus speeds up—the ability to develop such Apps. We applaud this initiative and caution against collecting private information on users. Some who seek to build centralised systems are pressuring Google and Apple to open up their systems to enable them to capture more data.

It is worth noting that the European Parliament on 17 April gave their support to the decentralised approach, pointing out by overwhelming majority “that […] the generated data are not to be stored in centralised databases, which are prone to potential risk of abuse and loss of trust and may endanger uptake throughout the Union” and demanding “that all storage of data be decentralised”.

There are a number of proposals for contact tracing methods which respect users’ privacy, many of which are being actively investigated for deployment by different countries. We urge all countries to rely only on systems that are subject to public scrutiny and that are privacy-preserving ​by design (instead of there being an expectation that they will be managed by a trustworthy party), as a means to ensure that the citizen’s data protection rights are upheld.

The following principles should be at least adopted going forward:

● Contact tracing Apps must only be used to support public health measures for the containment of COVID-19. The system must not be capable of collecting, processing, or transmitting any more data than what is necessary to achieve this purpose.

● Any considered solution must be fully transparent. The protocols and their implementations, including any sub-components provided by companies, must be available for public analysis. The processed data and if, how, where, and for how long they are stored must be documented unambiguously. Such data collected should be minimal for the given purpose.

● When multiple possible options to implement a certain component or functionality of the app exist, then the most privacy-preserving option must be chosen. Deviations from this principle are only permissible if this is necessary to achieve the purpose of the app more effectively, and must be clearly justified with sunset provisions

● The use of contact tracing Apps and the systems that support them must be voluntary, used with the explicit consent of the user and the systems must be designed to be able to be switched off, and all data deleted, when the current crisis is over.


Australia Prof. Dali Kaafar Macquarie University Prof. Vanessa Teague Thinking Cybersecurity and Australian National University Dr. Yuval Yarom The University of Adelaide and Data61

Austria Prof. Daniel Gruss Graz University of Technology Prof. Stefan Mangard Graz University of Technology Prof. Elisabeth Oswald University of Klagenfurt Prof. Christian Rechberger Graz University of Technology

Belgium Prof. Claudia Diaz KU Leuven Prof. Mireille Hildebrandt VU Brussels Prof. Wouter Joosen KU Leuven Prof. Nele Mentens KU Leuven Prof. Bart De Moor KU Leuven Fellow IEEE and SIAM Prof. Yves Moreau KU Leuven Fellow ISCB Prof. Olivier Pereira UC Louvain Prof. Frank Piessens KU Leuven Prof. Bart Preneel KU Leuven Fellow IACR Prof. Jean-Jacques Quisquater UCLouvain Fellow IACR, Member of Belgium Royal Academy Prof. Nigel Smart KU Leuven Fellow IACR Prof. François-Xavier Standaert UC Louvain Prof. Joos Vandewalle KU Leuven Fellow IEEE, IET, Eurasip, Member Royal Academy of Belgium and Academia Europaea Prof. Ingrid Verbauwhede KU Leuven Fellow IEEE and Royal Academy of Belgium Prof. Frederik Vercauteren KU Leuven Dr. Mathias Vermeulen VU Brussels

Brazil Prof. Mário S. Alvim Universidade Federal de Minas Gerais

Canada Prof. Vijay Ganesh University of Waterloo Prof. Ian Goldberg University of Waterloo Prof. Sergey Gorbunov University of Waterloo Prof. Xi He University of Waterloo. Prof. Florian Kerschbaum University of Waterloo Prof. Marc-Olivier Killijian Université du Québec à Montréal Prof. Ali José Mashtizadeh University of Waterloo Prof. Alfred Menezes University of Waterloo Prof. Bessma Momani University of Waterloo Prof. Michele Mosca University of Waterloo Prof. Paul van Oorschot Carleton University Fellow ACM, IEEE and Royal Soc. Canada Prof. Douglas Stebila University of Waterloo Prof. Charles Taylor McGill University

Denmark Prof. Ivan Damgård Aarhus University Fellow IACR Prof. Claudio Orlandi Aarhus University

Estonia Dr. Dan Bogdanov Cybernetica

Finland Prof. Chris Brzuska Aalto University

France Prof. Davide Balzarotti EURECOM Prof. Karim Belabas University of Bordeaux Dr. Olivier Blazy University of Limoges Dr. Jean-François Couchot University of Franche-Comté Prof. Aurélien Francillon EURECOM Prof. Nadia El Mrabet HDR Mines Saint-Etienne Dr. Rémi Géraud-Stewart CentraleSupélec Prof. Jean-Gabriel Ganascia Sorbonne University Fellow EURAI Prof. Louis Goubin University of Versailles St-Quentin-en-Yvelines Prof. Stefan Haar INRIA (Mexico Team) Prof. David Kohel Aix-Marseille University Dr. Pascal Lafourcade University Clermont Auvergne Dr. Benoît Libert ENS Lyon and CNRS Prof. Francois Morain LIX, Ecole Polytechnique Prof. David Naccache ENS Paris Prof. Melek Önen EURECOM Dr. Pascal Paillier Zama Prof. Benjamin Nguyen INSA Centre Val de Loire Prof. Michaël Quisquater University of Versailles Prof. Damien Stehlé ENS Lyon Prof. Jacques Stern ENS Paris Fellow IACR Prof. Massimiliano Todisco EURECOM

Germany Prof. Michael Backes CISPA Helmholtz Center for Information Security Fellow IEEE Prof. Eric Bodden Heinz Nixdorf Institute at Paderborn University & Fraunhofer IEM Prof. Georg Borges Saarland University Dr. Sven Bugiel CISPA Helmholtz Center for Information Security Prof. Stefan Brunthaler Universität der Bundeswehr München Prof. Cas Cremers CISPA Helmholtz Center for Information Security Dr. Jean Paul Degabriele TU Darmstadt Dr. Alexander Dix European Academy for Freedom of Information and Data Protection Prof. Christian Djeffal TU München Prof. Hannes Federrath University of Hamburg President of German Computer Society Prof. Bernd Finkbeiner CISPA Helmholtz Center for Information Security Dr. Michael Friedewald Fraunhofer ISI Prof. Mario Fritz CISPA Helmholtz Center for Information Security Prof. Sascha Fahl Leibniz University Hannover Prof. Nils Fleischhacker Ruhr-Universität Bochum Prof. Dominik Herrmann University of Bamberg Prof. Jeanette Hofmann Wissenschaftszentrum Berlin für Sozialforschung Prof. Thorsten Holz Ruhr-Universität Bochum Prof. Albert Ingold Johannes Gutenberg Universität Mainz Dr. Swen Jacobs CISPA Helmholtz Center for Information Security Prof. Tibor Jager University of Wuppertal Dr. Ghassan Karame NEC Laboratories Europe Dr. Christian Katzenbach Humboldt Institute for Internet and Society, Berlin Prof. Eike Kiltz Ruhr-Universität Bochum Dr. Dennis-Kenji Kipker European Academy for Freedom of Information and Data Protection Prof. Teresa Koloma Beck Universität der Bundeswehr München Dr. Katharina Krombholz CISPA Helmholtz Center for Information Security Prof. Jörn Lamla Universität Kassel
Prof. Gregor Leander Ruhr-Universität Bochum Prof. Anja Lehmann Hasso-Plattner-Institute and University of Potsdam Prof. Mira Mezini TU Darmstadt Member Nat. Acad. of Engineering Sciences Prof. Patrizia Nanz University of Potsdam Prof. Paul Nolte Freie Universität Berlin Prof. Christof Paar Max Planck Inst. CyberSec. and PrivacyFellow IACR and IEEE Dr. Sebastian Pape Goethe University Frankfurt Dr. Giancarlo Pellegrino CISPA Helmholtz Center for Information Security Prof. Hartmut Pohl softScheck GmbH Dr. Tina Pollmann TU München Prof. Jörn Müller-Quade KIT Karlsruhe Prof. Kai Rannenberg Goethe University Frankfurt Vice President IFIP Prof. Steffen Reith RheinMain University of Applied Sciences Prof. Elisa Resconi TU München Prof. Alexander Roßnagel University of Kassel Prof. M Angela Sasse Ruhr Universität Bochum Prof. Ina Schiering Ostfalia University of Applied Sciences Prof. Sebastian Schinzel Münster University of Applied Sciences Prof. Stefan Schönert TU München Prof. Jörg Schwenk Ruhr University Bochum Prof. Juraj Somorovsky Paderborn University Prof. Christoph Sorge Universität des Saarlandes Dr. Ben Stock CISPA Helmholtz Center for Information Security Prof. Thorsten Strufe KIT Karlsruhe and CeTI TU Dresden Dr. Nils Ole Tippenhauer CISPA Helmholtz Center for Information Security Prof. Jilles Vreeken CISPA Helmholtz Center for Information Security Prof. Andreas Zeller CISPA Helmholtz Center for Information Security Fellow ACM

India Prof. Subhamoy Maitra Indian Statistical Institute Dr. Mridul Nandi Indian Statistical Institute Prof. Manoj Prabhakaran IIT Bombay Dr. Somitra Kr. Sanadhya IIT Ropar Prof. Sandeep Kumar Shukla IIT Kanpur Fellow IEEE

Italy Prof. Rainer Bauböck European University Institute, Florence Prof. Carlo Blundo Università di Salerno Prof. Dario Catalano Università di Catania Prof. Ciro Cattuto University of Turin Prof. Giovanni Comandé Scuola Superiore Sant’Anna, Pisa Prof. Mauro Conti Università di Padova Prof. Giuseppe Persiano Università di Salerno Prof. Daniele Venturi Sapienza University of Rome Prof. Ivan Visconti University of Salerno

Israel Prof. Katya Assaf Hebrew University Prof. Yehuda Lindell Bar-Ilan University Prof. Benny Pinkas Bar-Ilan University

Japan Prof. Tetsu Iwata Nagoya University Prof. Kazuo Sakiyama UEC Tokyo

Luxembourg Prof. Peter Y A Ryan University of Luxembourg

Portugal Dr. Manuel Barbosa University of Porto (FCUP) and INESC TEC

Mexico Dr. Cuauhtemoc Mancillas-López CINVESTAV-IPN Dr. Brisbane Ovilla-Martínezm CINVESTAV-IPN Dr. Francisco Rodríguez-Henríquez CINVESTAV-IPN

The Netherlands Prof. Lejla Batina Radboud University Prof. Peter Boncz CWI Amsterdam and VU University Amsterdam Prof. Jos Baeten CWI Amsterdam and University of Amsterdam Prof. Ronald Cramer CWI Amsterdam and Leiden University Fellow IACR Prof. Joan Daemen Radboud University Prof. Arie van Deursen TU Delft Prof. Aaron Ding TU Delft Dr. Leo Ducas CWI Amsterdam Prof. Michel van Eeten TU Delft Prof. Serge Fehr CWI Amsterdam and Leiden University Prof. Tobias Fiebig TU Delft Prof. Natali Helberger University of Amsterdam Prof. Lisa Herzog University of Groningen Prof. Marijn Janssen TU Delft Prof. Tanja Lange Eindhoven University of Technology Prof. Arno R. Lodder Vrije Universiteit​ ​ Amsterdam Prof. Veelasha Moonsamy Radboud University Prof. Stefanie Roos TU Delft Prof. Peter Schwabe Radboud University Dr. Benne de Weger Eindhoven University of Technology Dr. Philip Zimmermann TU Delft

New Zealand Prof. Steven Galbraith University of Auckland

Norway Prof. Kristian Gjøsteen NTNU

Slovenia Prof. Marko Holbl University of Maribor

Spain Prof. Manuel Carro IMDEA Software Institute and Technical University of Madrid Prof. Ignacio Cascudo IMDEA Software Institute Gemma Galdon Clavell Eticas Foundation Prof. Dario Fiore IMDEA Software Institute Prof. Ramon Lopez de MantarasArtificial Intelligence Research Institute Fellow of EurAI Prof. Juan Tapiador UC3M Prof. Narseo Vallina-Rodriguez IMDEA Networks Institute Prof. María Isabel González Vasco Universidad Rey Juan Carlos

Sweden Prof. Rose-Mharie Åhlfeldt University of Skövde Dr. Matthias Beckerle Karlstad University Prof. Simone Fischer-Hübner Karlstad University Dr. Leonardo Martucci Karlstad University Mr. Linus Nordberg DFRI Dr. Tobias Pulls Karlstad University

Switzerland Prof. David Basin ETH Zurich Fellow ACM Dr. Peter Berlich ZHAW Dr. Jan Beutel ETH Zurich Prof. Edouard Bugnion EPFL Fellow ACM Prof. Christian Cachin University of Bern Fellow ACM and IEEE Prof. Srdjan Čapkun ETH Zurich Fellow ACM Prof. Bryan Ford EPFL Prof. Dennis Hofheinz ETH Zurich Prof. Jean-Pierre Hubaux EPFL Fellow ACM and IEEE Prof. James Larus EPFL Fellow ACM Prof. Ueli Maurer ETH Zurich Fellow ACM, IACR and IEEE Prof. Adrian Perrig ETH Zurich Fellow ACM Prof. Kenny Paterson ETH Zurich Fellow IACR Prof. Mathias Payer EPFL Prof. Kaveh Razavi ETH Zurich Prof. Marcel Salath​é EPFL Prof. Carmela Troncoso EPFL

United Arab Emirates Prof. Christina Pöpper New York University, Abu Dhabi.

United Kingdom Prof. Martin Albrecht Royal Holloway, University of London Dr. Reuben Binns University of Oxford Prof. Lorenzo Cavallaro King’s College London Prof. Liqun Chen University of Surrey Prof. Carlos Cid Royal Holloway, University of London Dr. Jennifer Cobbe University of Cambridge Prof. Jon Crowcroft University of CambridgeFRS, FREng Fellow ACM and IEEE Prof. George Danezis UCL Prof. Lilian Edwards Newcastle University Prof. Flavio Garcia University of Birmingham Dr. Robert Granger University of Surrey Dr. Jassim Happa Royal Holloway, University of London. Dr. Rikke Bjerg Jensen Royal Holloway, University of London Dr. Philipp Jovanovic UCL Prof. Aggelos Kiayias University of Edinburgh Prof. Christopher Marsden University of Sussex Prof. Keith Martin Royal Holloway, University of London Prof. Ivan Martinovic University of Oxford Dr. Tim Muller University of Nottingham Dr. Dan Page University of Bristol Dr. Elizabeth Quaglia Royal Holloway, University of London Prof. Mark D. Ryan University of Birmingham Prof. Burkhard Schafer University of Edinburgh Prof. Steve Schneider University of Surrey Fellow IET Dr. Jat Singh University of Cambridge Prof. Max Van Kleek University of Oxford Dr. Michael Veale UCL Prof. Alan Woodward University of Surrey Fellow BCS and InstP Dr. Vassiles Zikas University of Edinburgh

United States of America Prof. Alessandro Acquisti Carnegie Mellon University Dr. Johanna Amann ICSI Prof. Adam Bates Uni. of Illinois at Urbana-Champaign Prof. Lujo Bauer Carnegie Mellon University Prof. Mihir Bellare UC San Diego Fellow ACM and IACR Prof. Daniel J. Bernstein University of Illinois at Chicago Prof. Matt Blaze Georgetown University Prof. Vincent Bindschaedler University of Florida Prof. Dan Boneh Stanford University Fellow ACM, IACR, US Nat. Acad. of Eng. Prof. Kevin Butler University of Florida Dr. Jon Callas ACLU Prof. L. Jean Camp Indiana University Fellow AAAS, IEEE Prof. Ran Canetti Boston University Fellow IACR Deirdre Connolly Zcash Foundation Prof. Nicolas Christin Carnegie Mellon Uni. Prof. Lorrie Cranor Carnegie Mellon Uni. Fellow ACM and IEEE Prof. Anupam Das North Carolina State Uni. Prof. Srinivas Devadas MIT Fellow ACM and IEEE Prof. Sven Dietrich City University of New York Prof. Marten van Dijk University of Connecticut and CWI Prof. Jintai Ding University of Cincinnati Roger Dingledine The Tor Project Dr. Roel Dobbe AI Now Institute (New York) Prof. Manuel Egele Boston University Prof. William Enck North Carolina State Uni. Prof. Shyam Gollakota University of Washington Prof. Matthew D. Green Johns Hopkins University Prof. Rachel Greenstadt New York University Prof. Giulia Fanti Carnegie Mellon University Prof. Dean Foster Uni. of Pennsylvania Fellow IMS and Game Theory Society Prof. Michael Franz UC Irvine Fellow AAAS, ACM, IEEE, and IFIP Prof. Britta Hale Naval Postgraduate School Dr. Mike Hamburg Rambus Dr. Helena Handschuh Rambus Fellow Prof. Trent Jaeger Pennsylvania State University Prof. Somesh Jha Uni. of Wisconsin, Madison Prof. Sham Kakade University of Washington Prof. Aniket Kate Purdue University Prof. Jonathan Katz George Mason Uni. Fellow IACR Dr. Hugo Krawczyk Algorand Foundation Fellow IACR Dr. Kristin E. Lauter Microsoft Research Prof. Susan Landau Tufts University Fellow ACM and AAAS Prof. Tadayoshi Kohno University of Washington Mr. John Langford Microsoft Research President of ICML Dr. Timothy Libert Carnegie Mellon University Prof. Anna Lysyanskaya Brown University Prof. David Mazières Stanford University Prof. Michelle Mazurek University of Maryland, College Park Prof. Patrick McDaniel Pennsylvania State Uni. Prof. Prateek Mittal Princeton University Prof. Rafail Ostrovsky UCLA Fellow IACR, IEEE, Member Academia Europea Prof. Aanjhan Ranganathan Northeastern University Prof. Bradley Reaves North Carolina State Uni. Prof. Franziska Roesner University of Washington Prof. Phil Rogaway UC Davis Fellow IACR Mr. Gregory Rose Deckard Technologies, Inc. Prof. Norman Sadeh Carnegie Mellon University Prof. Alessandra Scafuro North Carolina State Uni. Prof. Patrick Schaumont Worcester Polytechnic Institute Prof. Micah Sherr Georgetown University Prof. Thomas Shrimpton University of Florida Prof. Dawn Song Fellow ACM, IEEE Prof. Philip B. Stark UC Berkeley Fellow ASA, Inst. Phys. and Royal Astronomy Soc. Prof. Stefano Tessaro University of Washington Prof. Patrick Traynor University of Florida Prof. Lyle Ungar University of Pennsylvania Henry de Valence Zcash Foundation Prof. Mayank Varia Boston University Prof. XiaoFeng Wang Indiana University Fellow IEEE Mr John Wilkinson MIT Prof. Byron Williams University of Florida Prof. Laurie Williams N. Carolina State Uni. Fellow IEEE Prof. Matthew Wright Rochester Institute of Technology Prof. Dongyan Xu Purdue University Prof. Xiangyu Zhang Purdue University


Privacy-preserving decentralized methods of the type referred to in this document include:

DP-3T​: ​ TCN

Coalition​: ​

PACT (MIT)​: ​

PACT​ ​(UW)​: ​

All these teams are committed to working together to make their systems interoperate. They aim to provide different decentralised privacy preserving methods which can be adapted by countries depending on their local situation. By working together they can ensure that using contact tracing in the effort to defeat COVID-19 can be done in a way that protects privacy.