Abstract
Contact tracing is a critical tool in containing epidemics such as COVID-19. Researchers have carried out a lot of work on contact tracing. However, almost all of the existing works assume that their clients and authorities have large storage space and powerful computation capability and clients can implement contact tracing on their own mobile devices such as mobile phones, tablet computers, and wearable computers. With the widespread outbreaks of the epidemics, these approaches are of less robustness to a larger scale of datasets when it comes to resource-constrained clients. To address this limitation, we propose a publicly verifiable contact tracing algorithm in cloud computing (PvCT), which utilizes cloud services to provide storage and computation capability in contact tracing. To guarantee the integrity and accuracy of contact tracing results, PvCT applies a novel set accumulator-based authentication data structure whose computation is outsourced, and the client can check whether returned results are valid. Furthermore, we provide rigorous security proof of our algorithm based on the q -Strong Bilinear Diffie–Hellman assumption. Detailed experimental evaluation is also conducted on three real-world datasets. The results show that our algorithm is feasible within milliseconds of client CPU time and can significantly reduce the storage overhead from the size of datasets to a constant 128 bytes.
Highlights
Contact tracing is a critical approach for identifying people who may have come into contact with diagnosed people infected with some epidemics such as Ebola virus disease, H1N1 influenza pandemic, or coronavirus disease 2019 (COVID-19)
In the proposed framework, an authenticated data structure (ADS) is generated for every individual of each client
Because our verification algorithm is independent of the retrieval algorithm, in other words, any existing retrieval algorithm such as [36] can be used in our construction and do not affect accuracy and security of our algorithm, we omit the detail of retrieval process here and only consider after Cloud Service Provider I (CSPI) finished its retrieval process and obtain the corresponding result Re. en, we can apply Setup(Re, pk) to generate a proof π and use a counter to obtain the number of result set numre as the verification object (VO) for the retrieval result
Summary
Contact tracing is a critical approach for identifying people who may have come into contact with diagnosed people infected with some epidemics such as Ebola virus disease, H1N1 influenza pandemic, or coronavirus disease 2019 (COVID-19). Almost all of the existing works assume that their clients and authorities have large storage space and powerful computation capability and clients can implement contact tracing on their own mobile devices such. Us, a more generic ADS is preferable to support different phases that may happen in contact tracing scenario To address this issue, we propose a novel set accumulator-based ADS scheme that enables public verification over contact tracing, guaranteeing both accuracy and integrity check. We provide each client and authority with an additional ADS Based on this ADS, untrusted CSP can construct and return a cryptographic proof, known as verification object (VO), for clients to verify the result of contact tracing.
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