@article{8978,
  abstract     = {Mosaic analysis with double markers (MADM) technology enables concomitant fluorescent cell labeling and induction of uniparental chromosome disomy (UPD) with single-cell resolution. In UPD, imprinted genes are either overexpressed 2-fold or are not expressed. Here, the MADM platform is utilized to probe imprinting phenotypes at the transcriptional level. This protocol highlights major steps for the generation and isolation of projection neurons and astrocytes with MADM-induced UPD from mouse cerebral cortex for downstream single-cell and low-input sample RNA-sequencing experiments.

For complete details on the use and execution of this protocol, please refer to Laukoter et al. (2020b).},
  author       = {Laukoter, Susanne and Amberg, Nicole and Pauler, Florian and Hippenmeyer, Simon},
  issn         = {2666-1667},
  journal      = {STAR Protocols},
  number       = {3},
  publisher    = {Elsevier},
  title        = {{Generation and isolation of single cells from mouse brain with mosaic analysis with double markers-induced uniparental chromosome disomy}},
  doi          = {10.1016/j.xpro.2020.100215},
  volume       = {1},
  year         = {2020},
}

@article{8038,
  abstract     = {Microelectromechanical systems and integrated photonics provide the basis for many reliable and compact circuit elements in modern communication systems. Electro-opto-mechanical devices are currently one of the leading approaches to realize ultra-sensitive, low-loss transducers for an emerging quantum information technology. Here we present an on-chip microwave frequency converter based on a planar aluminum on silicon nitride platform that is compatible with slot-mode coupled photonic crystal cavities. We show efficient frequency conversion between two propagating microwave modes mediated by the radiation pressure interaction with a metalized dielectric nanobeam oscillator. We achieve bidirectional coherent conversion with a total device efficiency of up to ~60%, a dynamic range of 2 × 10^9 photons/s and an instantaneous bandwidth of up to 1.7 kHz. A high fidelity quantum state transfer would be possible if the drive dependent output noise of currently ~14 photons s^−1 Hz^−1 is further reduced. Such a silicon nitride based transducer is in situ reconfigurable and could be used for on-chip classical and quantum signal routing and filtering, both for microwave and hybrid microwave-optical applications.},
  author       = {Fink, Johannes M and Kalaee, M. and Norte, R. and Pitanti, A. and Painter, O.},
  issn         = {2058-9565},
  journal      = {Quantum Science and Technology},
  number       = {3},
  publisher    = {IOP Publishing},
  title        = {{Efficient microwave frequency conversion mediated by a photonics compatible silicon nitride nanobeam oscillator}},
  doi          = {10.1088/2058-9565/ab8dce},
  volume       = {5},
  year         = {2020},
}

@article{7910,
  abstract     = {Quantum illumination uses entangled signal-idler photon pairs to boost the detection efficiency of low-reflectivity objects in environments with bright thermal noise. Its advantage is particularly evident at low signal powers, a promising feature for applications such as noninvasive biomedical scanning or low-power short-range radar. Here, we experimentally investigate the concept of quantum illumination at microwave frequencies. We generate entangled fields to illuminate a room-temperature object at a distance of 1 m in a free-space detection setup. We implement a digital phase-conjugate receiver based on linear quadrature measurements that outperforms a symmetric classical noise radar in the same conditions, despite the entanglement-breaking signal path. Starting from experimental data, we also simulate the case of perfect idler photon number detection, which results in a quantum advantage compared with the relative classical benchmark. Our results highlight the opportunities and challenges in the way toward a first room-temperature application of microwave quantum circuits.},
  author       = {Barzanjeh, Shabir and Pirandola, S. and Vitali, D and Fink, Johannes M},
  issn         = {2375-2548},
  journal      = {Science Advances},
  number       = {19},
  publisher    = {AAAS},
  title        = {{Microwave quantum illumination using a digital receiver}},
  doi          = {10.1126/sciadv.abb0451},
  volume       = {6},
  year         = {2020},
}

@inproceedings{9001,
  abstract     = {Quantum illumination is a sensing technique that employs entangled signal-idler beams to improve the detection efficiency of low-reflectivity objects in environments with large thermal noise. The advantage over classical strategies is evident at low signal brightness, a feature which could make the protocol an ideal prototype for non-invasive scanning or low-power short-range radar. Here we experimentally investigate the concept of quantum illumination at microwave frequencies, by generating entangled fields using a Josephson parametric converter which are then amplified to illuminate a room-temperature object at a distance of 1 meter. Starting from experimental data, we simulate the case of perfect idler photon number detection, which results in a quantum advantage compared to the relative classical benchmark. Our results highlight the opportunities and challenges on the way towards a first room-temperature application of microwave quantum circuits.},
  author       = {Barzanjeh, Shabir and Pirandola, Stefano and Vitali, David and Fink, Johannes M},
  booktitle    = {IEEE National Radar Conference - Proceedings},
  isbn         = {9781728189420},
  issn         = {1097-5659},
  location     = {Florence, Italy},
  number       = {9},
  publisher    = {IEEE},
  title        = {{Microwave quantum illumination with a digital phase-conjugated receiver}},
  doi          = {10.1109/RadarConf2043947.2020.9266397},
  volume       = {2020},
  year         = {2020},
}

@misc{13070,
  abstract     = {This dataset comprises all data shown in the figures of the submitted article "Surpassing the resistance quantum with a geometric superinductor". Additional raw data are available from the corresponding author on reasonable request.},
  author       = {Peruzzo, Matilda and Trioni, Andrea and Hassani, Farid and Zemlicka, Martin and Fink, Johannes M},
  publisher    = {Zenodo},
  title        = {{Surpassing the resistance quantum with a geometric superinductor}},
  doi          = {10.5281/ZENODO.4052882},
  year         = {2020},
}

@misc{13071,
  abstract     = {This dataset comprises all data shown in the plots of the main part of the submitted article "Bidirectional Electro-Optic Wavelength Conversion in the Quantum Ground State". Additional raw data are available from the corresponding author on reasonable request.},
  author       = {Hease, William J and Rueda Sanchez, Alfredo R and Sahu, Rishabh and Wulf, Matthias and Arnold, Georg M and Schwefel, Harald and Fink, Johannes M},
  publisher    = {Zenodo},
  title        = {{Bidirectional electro-optic wavelength conversion in the quantum ground state}},
  doi          = {10.5281/ZENODO.4266025},
  year         = {2020},
}

@article{8535,
  abstract     = {We propose a method to enhance the visual detail of a water surface simulation. Our method works as a post-processing step which takes a simulation as input and increases its apparent resolution by simulating many detailed Lagrangian water waves on top of it. We extend linear water wave theory to work in non-planar domains which deform over time, and we discretize the theory using Lagrangian wave packets attached to spline curves. The method is numerically stable and trivially parallelizable, and it produces high frequency ripples with dispersive wave-like behaviors customized to the underlying fluid simulation.},
  author       = {Skrivan, Tomas and Soderstrom, Andreas and Johansson, John and Sprenger, Christoph and Museth, Ken and Wojtan, Christopher J},
  issn         = {1557-7368},
  journal      = {ACM Transactions on Graphics},
  number       = {4},
  publisher    = {Association for Computing Machinery},
  title        = {{Wave curves: Simulating Lagrangian water waves on dynamically deforming surfaces}},
  doi          = {10.1145/3386569.3392466},
  volume       = {39},
  year         = {2020},
}

@article{7339,
  abstract     = {Cytoskeletal filaments such as microtubules (MTs) and filamentous actin (F-actin) dynamically support cell structure and functions. In central presynaptic terminals, F-actin is expressed along the release edge and reportedly plays diverse functional roles, but whether axonal MTs extend deep into terminals and play any physiological role remains controversial. At the calyx of Held in rats of either sex, confocal and high-resolution microscopy revealed that MTs enter deep into presynaptic terminal swellings and partially colocalize with a subset of synaptic vesicles (SVs). Electrophysiological analysis demonstrated that depolymerization of MTs specifically prolonged the slow-recovery time component of EPSCs from short-term depression induced by a train of high-frequency stimulation, whereas depolymerization of F-actin specifically prolonged the fast-recovery component. In simultaneous presynaptic and postsynaptic action potential recordings, depolymerization of MTs or F-actin significantly impaired the fidelity of high-frequency neurotransmission. We conclude that MTs and F-actin differentially contribute to slow and fast SV replenishment, thereby maintaining high-frequency neurotransmission.},
  author       = {Piriya Ananda Babu, Lashmi and Wang, Han Ying and Eguchi, Kohgaku and Guillaud, Laurent and Takahashi, Tomoyuki},
  issn         = {1529-2401},
  journal      = {Journal of neuroscience},
  number       = {1},
  pages        = {131--142},
  publisher    = {Society for Neuroscience},
  title        = {{Microtubule and actin differentially regulate synaptic vesicle cycling to maintain high-frequency neurotransmission}},
  doi          = {10.1523/JNEUROSCI.1571-19.2019},
  volume       = {40},
  year         = {2020},
}

@article{8170,
  abstract     = {Alignment of OCS, CS2, and I2 molecules embedded in helium nanodroplets is measured as a function
of time following rotational excitation by a nonresonant, comparatively weak ps laser pulse. The distinct
peaks in the power spectra, obtained by Fourier analysis, are used to determine the rotational, B, and
centrifugal distortion, D, constants. For OCS, B and D match the values known from IR spectroscopy. For
CS2 and I2, they are the first experimental results reported. The alignment dynamics calculated from the
gas-phase rotational Schrödinger equation, using the experimental in-droplet B and D values, agree in
detail with the measurement for all three molecules. The rotational spectroscopy technique for molecules in
helium droplets introduced here should apply to a range of molecules and complexes.},
  author       = {Chatterley, Adam S. and Christiansen, Lars and Schouder, Constant A. and Jørgensen, Anders V. and Shepperson, Benjamin and Cherepanov, Igor and Bighin, Giacomo and Zillich, Robert E. and Lemeshko, Mikhail and Stapelfeldt, Henrik},
  issn         = {1079-7114},
  journal      = {Physical Review Letters},
  number       = {1},
  publisher    = {American Physical Society},
  title        = {{Rotational coherence spectroscopy of molecules in Helium nanodroplets: Reconciling the time and the frequency domains}},
  doi          = {10.1103/PhysRevLett.125.013001},
  volume       = {125},
  year         = {2020},
}

@article{7656,
  abstract     = {We propose that correlations among neurons are generically strong enough to organize neural activity patterns into a discrete set of clusters, which can each be viewed as a population codeword. Our reasoning starts with the analysis of retinal ganglion cell data using maximum entropy models, showing that the population is robustly in a frustrated, marginally sub-critical, or glassy, state. This leads to an argument that neural populations in many other brain areas might share this structure. Next, we use latent variable models to show that this glassy state possesses well-defined clusters of neural activity. Clusters have three appealing properties: (i) clusters exhibit error correction, i.e., they are reproducibly elicited by the same stimulus despite variability at the level of constituent neurons; (ii) clusters encode qualitatively different visual features than their constituent neurons; and (iii) clusters can be learned by downstream neural circuits in an unsupervised fashion. We hypothesize that these properties give rise to a “learnable” neural code which the cortical hierarchy uses to extract increasingly complex features without supervision or reinforcement.},
  author       = {Berry, Michael J. and Tkačik, Gašper},
  issn         = {1662-5188},
  journal      = {Frontiers in Computational Neuroscience},
  publisher    = {Frontiers},
  title        = {{Clustering of neural activity: A design principle for population codes}},
  doi          = {10.3389/fncom.2020.00020},
  volume       = {14},
  year         = {2020},
}

@article{7603,
  abstract     = {Plants are exposed to a variety of abiotic and biotic stresses that may result in DNA damage. Endogenous processes - such as DNA replication, DNA recombination, respiration, or photosynthesis - are also a threat to DNA integrity. It is therefore essential to understand the strategies plants have developed for DNA damage detection, signaling, and repair. Alternative splicing (AS) is a key post-transcriptional process with a role in regulation of gene expression. Recent studies demonstrate that the majority of intron-containing genes in plants are alternatively spliced, highlighting the importance of AS in plant development and stress response. Not only does AS ensure a versatile proteome and influence the abundance and availability of proteins greatly, it has also emerged as an important player in the DNA damage response (DDR) in animals. Despite extensive studies of DDR carried out in plants, its regulation at the level of AS has not been comprehensively addressed. Here, we provide some insights into the interplay between AS and DDR in plants.},
  author       = {Nimeth, Barbara Anna and Riegler, Stefan and Kalyna, Maria},
  issn         = {1664-462X},
  journal      = {Frontiers in Plant Science},
  publisher    = {Frontiers},
  title        = {{Alternative splicing and DNA damage response in plants}},
  doi          = {10.3389/fpls.2020.00091},
  volume       = {11},
  year         = {2020},
}

@article{7212,
  abstract     = {The fixation probability of a single mutant invading a population of residents is among the most widely-studied quantities in evolutionary dynamics. Amplifiers of natural selection are population structures that increase the fixation probability of advantageous mutants, compared to well-mixed populations. Extensive studies have shown that many amplifiers exist for the Birth-death Moran process, some of them substantially increasing the fixation probability or even guaranteeing fixation in the limit of large population size. On the other hand, no amplifiers are known for the death-Birth Moran process, and computer-assisted exhaustive searches have failed to discover amplification. In this work we resolve this disparity, by showing that any amplification under death-Birth updating is necessarily bounded and transient. Our boundedness result states that even if a population structure does amplify selection, the resulting fixation probability is close to that of the well-mixed population. Our transience result states that for any population structure there exists a threshold r⋆ such that the population structure ceases to amplify selection if the mutant fitness advantage r is larger than r⋆. Finally, we also extend the above results to δ-death-Birth updating, which is a combination of Birth-death and death-Birth updating. On the positive side, we identify population structures that maintain amplification for a wide range of values r and δ. These results demonstrate that amplification of natural selection depends on the specific mechanisms of the evolutionary process.},
  author       = {Tkadlec, Josef and Pavlogiannis, Andreas and Chatterjee, Krishnendu and Nowak, Martin A.},
  issn         = {1553-7358},
  journal      = {PLoS computational biology},
  publisher    = {Public Library of Science},
  title        = {{Limits on amplifiers of natural selection under death-Birth updating}},
  doi          = {10.1371/journal.pcbi.1007494},
  volume       = {16},
  year         = {2020},
}

@article{8384,
  abstract     = {Previous research on animations of soap bubbles, films, and foams largely focuses on the motion and geometric shape of the bubble surface. These works neglect the evolution of the bubble’s thickness, which is normally responsible for visual phenomena like surface vortices, Newton’s interference patterns, capillary waves, and deformation-dependent rupturing of films in a foam. In this paper, we model these natural phenomena by introducing the film thickness as a reduced degree of freedom in the Navier-Stokes equations and deriving their equations of motion. We discretize the equations on a nonmanifold triangle mesh surface and couple it to an existing bubble solver. In doing so, we also introduce an incompressible fluid solver for 2.5D films and a novel advection algorithm for convecting fields across non-manifold surface junctions. Our simulations enhance state-of-the-art bubble solvers with additional effects caused by convection, rippling, draining, and evaporation of the thin film.},
  author       = {Ishida, Sadashige and Synak, Peter and Narita, Fumiya and Hachisuka, Toshiya and Wojtan, Christopher J},
  issn         = {1557-7368},
  journal      = {ACM Transactions on Graphics},
  number       = {4},
  publisher    = {Association for Computing Machinery},
  title        = {{A model for soap film dynamics with evolving thickness}},
  doi          = {10.1145/3386569.3392405},
  volume       = {39},
  year         = {2020},
}

@article{8385,
  abstract     = {We present a method for animating yarn-level cloth effects using a thin-shell solver. We accomplish this through numerical homogenization: we first use a large number of yarn-level simulations to build a model of the potential energy density of the cloth, and then use this energy density function to compute forces in a thin shell simulator. We model several yarn-based materials, including both woven and knitted fabrics. Our model faithfully reproduces expected effects like the stiffness of woven fabrics, and the highly deformable nature and anisotropy of knitted fabrics. Our approach does not require any real-world experiments nor measurements; because the method is based entirely on simulations, it can generate entirely new material models quickly, without the need for testing apparatuses or human intervention. We provide data-driven models of several woven and knitted fabrics, which can be used for efficient simulation with an off-the-shelf cloth solver.},
  author       = {Sperl, Georg and Narain, Rahul and Wojtan, Christopher J},
  issn         = {1557-7368},
  journal      = {ACM Transactions on Graphics},
  number       = {4},
  publisher    = {Association for Computing Machinery},
  title        = {{Homogenized yarn-level cloth}},
  doi          = {10.1145/3386569.3392412},
  volume       = {39},
  year         = {2020},
}

@phdthesis{7196,
  abstract     = {In this thesis we study certain mathematical aspects of evolution. The two primary forces that drive an evolutionary process are mutation and selection. Mutation generates new variants in a population. Selection chooses among the variants depending on the reproductive rates of individuals. Evolutionary processes are intrinsically random – a new mutation that is initially present in the population at low frequency can go extinct, even if it confers a reproductive advantage. The overall rate of evolution is largely determined by two quantities: the probability that an invading advantageous mutation spreads through the population (called fixation probability) and the time until it does so (called fixation time). Both those quantities crucially depend not only on the strength of the invading mutation but also on the population structure. In this thesis, we aim to understand how the underlying population structure affects the overall rate of evolution. Specifically, we study population structures that increase the fixation probability of advantageous mutants (called amplifiers of selection). Broadly speaking, our results are of three different types: We present various strong amplifiers, we identify regimes under which only limited amplification is feasible, and we propose population structures that provide different tradeoffs between high fixation probability and short fixation time.},
  author       = {Tkadlec, Josef},
  issn         = {2663-337X},
  pages        = {144},
  publisher    = {Institute of Science and Technology Austria},
  title        = {{A role of graphs in evolutionary processes}},
  doi          = {10.15479/AT:ISTA:7196},
  year         = {2020},
}

@inbook{8173,
  abstract     = {Understanding how the activity of membrane receptors and cellular signaling pathways shapes cell behavior is of fundamental interest in basic and applied research. Reengineering receptors to react to light instead of their cognate ligands allows for generating defined signaling inputs with high spatial and temporal precision and facilitates the dissection of complex signaling networks. Here, we describe fundamental considerations in the design of light-regulated receptor tyrosine kinases (Opto-RTKs) and appropriate control experiments. We also introduce methods for transient receptor expression in HEK293 cells, quantitative assessment of signaling activity in reporter gene assays, semiquantitative assessment of (in)activation time courses through Western blot (WB) analysis, and easy to implement light stimulation hardware.},
  author       = {Kainrath, Stephanie and Janovjak, Harald L},
  booktitle    = {Photoswitching Proteins},
  editor       = {Niopek, Dominik},
  isbn         = {9781071607541},
  issn         = {1940-6029},
  pages        = {233--246},
  publisher    = {Springer Nature},
  title        = {{Design and application of light-regulated receptor tyrosine kinases}},
  doi          = {10.1007/978-1-0716-0755-8_16},
  volume       = {2173},
  year         = {2020},
}

@inproceedings{8272,
  abstract     = {We study turn-based stochastic zero-sum games with lexicographic preferences over reachability and safety objectives. Stochastic games are standard models in control, verification, and synthesis of stochastic reactive systems that exhibit both randomness as well as angelic and demonic non-determinism. Lexicographic order allows to consider multiple objectives with a strict preference order over the satisfaction of the objectives. To the best of our knowledge, stochastic games with lexicographic objectives have not been studied before. We establish determinacy of such games and present strategy and computational complexity results. For strategy complexity, we show that lexicographically optimal strategies exist that are deterministic and memory is only required to remember the already satisfied and violated objectives. For a constant number of objectives, we show that the relevant decision problem is in   NP∩coNP , matching the current known bound for single objectives; and in general the decision problem is   PSPACE -hard and can be solved in   NEXPTIME∩coNEXPTIME . We present an algorithm that computes the lexicographically optimal strategies via a reduction to computation of optimal strategies in a sequence of single-objectives games. We have implemented our algorithm and report experimental results on various case studies.},
  author       = {Chatterjee, Krishnendu and Katoen, Joost P and Weininger, Maximilian and Winkler, Tobias},
  booktitle    = {International Conference on Computer Aided Verification},
  isbn         = {9783030532901},
  issn         = {1611-3349},
  pages        = {398--420},
  publisher    = {Springer Nature},
  title        = {{Stochastic games with lexicographic reachability-safety objectives}},
  doi          = {10.1007/978-3-030-53291-8_21},
  volume       = {12225},
  year         = {2020},
}

@article{8674,
  abstract     = {Extrasynaptic actions of glutamate are limited by high-affinity transporters expressed by perisynaptic astroglial processes (PAPs): this helps maintain point-to-point transmission in excitatory circuits. Memory formation in the brain is associated with synaptic remodeling, but how this affects PAPs and therefore extrasynaptic glutamate actions is poorly understood. Here, we used advanced imaging methods, in situ and in vivo, to find that a classical synaptic memory mechanism, long-term potentiation (LTP), triggers withdrawal of PAPs from potentiated synapses. Optical glutamate sensors combined with patch-clamp and 3D molecular localization reveal that LTP induction thus prompts spatial retreat of astroglial glutamate transporters, boosting glutamate spillover and NMDA-receptor-mediated inter-synaptic cross-talk. The LTP-triggered PAP withdrawal involves NKCC1 transporters and the actin-controlling protein cofilin but does not depend on major Ca2+-dependent cascades in astrocytes. We have therefore uncovered a mechanism by which a memory trace at one synapse could alter signal handling by multiple neighboring connections.},
  author       = {Henneberger, Christian and Bard, Lucie and Panatier, Aude and Reynolds, James P. and Kopach, Olga and Medvedev, Nikolay I. and Minge, Daniel and Herde, Michel K. and Anders, Stefanie and Kraev, Igor and Heller, Janosch P. and Rama, Sylvain and Zheng, Kaiyu and Jensen, Thomas P. and Sanchez-Romero, Inmaculada and Jackson, Colin J. and Janovjak, Harald L and Ottersen, Ole Petter and Nagelhus, Erlend Arnulf and Oliet, Stephane H.R. and Stewart, Michael G. and Nägerl, U. VAlentin and Rusakov, Dmitri A. },
  issn         = {1097-4199},
  journal      = {Neuron},
  number       = {5},
  pages        = {P919--936.E11},
  publisher    = {Elsevier},
  title        = {{LTP induction boosts glutamate spillover by driving withdrawal of perisynaptic astroglia}},
  doi          = {10.1016/j.neuron.2020.08.030},
  volume       = {108},
  year         = {2020},
}

@inproceedings{8339,
  abstract     = {Discrete Gaussian distributions over lattices are central to lattice-based cryptography, and to the computational and mathematical aspects of lattices more broadly. The literature contains a wealth of useful theorems about the behavior of discrete Gaussians under convolutions and related operations. Yet despite their structural similarities, most of these theorems are formally incomparable, and their proofs tend to be monolithic and written nearly “from scratch,” making them unnecessarily hard to verify, understand, and extend.
In this work we present a modular framework for analyzing linear operations on discrete Gaussian distributions. The framework abstracts away the particulars of Gaussians, and usually reduces proofs to the choice of appropriate linear transformations and elementary linear algebra. To showcase the approach, we establish several general properties of discrete Gaussians, and show how to obtain all prior convolution theorems (along with some new ones) as straightforward corollaries. As another application, we describe a self-reduction for Learning With Errors (LWE) that uses a fixed number of samples to generate an unlimited number of additional ones (having somewhat larger error). The distinguishing features of our reduction are its simple analysis in our framework, and its exclusive use of discrete Gaussians without any loss in parameters relative to a prior mixed discrete-and-continuous approach.
As a contribution of independent interest, for subgaussian random matrices we prove a singular value concentration bound with explicitly stated constants, and we give tighter heuristics for specific distributions that are commonly used for generating lattice trapdoors. These bounds yield improvements in the concrete bit-security estimates for trapdoor lattice cryptosystems.},
  author       = {Genise, Nicholas and Micciancio, Daniele and Peikert, Chris and Walter, Michael},
  booktitle    = {23rd IACR International Conference on the Practice and Theory of Public-Key Cryptography},
  isbn         = {9783030453732},
  issn         = {1611-3349},
  location     = {Edinburgh, United Kingdom},
  pages        = {623--651},
  publisher    = {Springer Nature},
  title        = {{Improved discrete Gaussian and subgaussian analysis for lattice cryptography}},
  doi          = {10.1007/978-3-030-45374-9_21},
  volume       = {12110},
  year         = {2020},
}

@inproceedings{8987,
  abstract     = {Currently several projects aim at designing and implementing protocols for privacy preserving automated contact tracing to help fight the current pandemic. Those proposal are quite similar, and in their most basic form 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 a user is tested positive, they upload either the beacons they did broadcast (which is the case in decentralized proposals as DP-3T, east and west coast PACT or Covid watch) or received (as in Popp-PT or ROBERT) during the last two weeks or so.

Vaudenay [eprint 2020/399] observes that this basic scheme (he considers the DP-3T proposal) succumbs to relay and even replay attacks, and proposes more complex interactive schemes which prevent those attacks without giving up too many privacy aspects. Unfortunately interaction is problematic for this application for efficiency and security reasons. The countermeasures that have been suggested so far are either not practical or give up on key privacy aspects. We propose a simple non-interactive variant of the basic protocol that
(security) Provably prevents replay and (if location data is available) relay attacks.
(privacy) The data of all parties (even jointly) reveals no information on the location or time where encounters happened.
(efficiency) The broadcasted message can fit into 128 bits and uses only basic crypto (commitments and secret key authentication).

Towards this end we introduce the concept of “delayed authentication”, which basically is a message authentication code where verification can be done in two steps, where the first doesn’t require the key, and the second doesn’t require the message.},
  author       = {Pietrzak, Krzysztof Z},
  booktitle    = {Progress in Cryptology},
  isbn         = {9783030652760},
  issn         = {1611-3349},
  location     = {Bangalore, India},
  pages        = {3--15},
  publisher    = {Springer Nature},
  title        = {{Delayed authentication: Preventing replay and relay attacks in private contact tracing}},
  doi          = {10.1007/978-3-030-65277-7_1},
  volume       = {12578},
  year         = {2020},
}

