Privacy in advanced cryptographic protocols: Prototypical examples

Abstract

Cryptography is a fundamental cornerstone of cybersecurity, traditionally supporting data confidentiality, integrity, and authenticity. However, when cryptographic protocols are deployed in emerging applications such as cloud services or big data, the demand for security grows beyond these requirements. Data nowadays are being extensively stored in the cloud, and users also need to trust the cloud servers/ authorities that run powerful applications. Collecting user data, combined with powerful tools (e.g., machine learning), can come with a huge risk of mass surveillance or of undesirable data-driven strategies for profit making, while ignoring users’ needs. Privacy, therefore, becomes more and more important, and new techniques should be developed, first, to protect personal privacy, and, second, to reduce centralized trust in authorities or in technical solutions providers. In a general sense, privacy is “the right to be left alone”; privacy protection allows individuals to have control over how their personal data is collected and used. Here, we discuss privacy protecting methods of various cryptographic protocols, in particular we review: Privacy in electronic voting systems. This is, perhaps, the most important real-world application where privacy plays a huge fundamental role. Private computation. This may be the widest domain in the new era of modern technologies with cloud computing and big data, where users delegate the storage of their data and its computation to the cloud. In such a situation, “how can we preserve privacy?” is one of the most important questions in cryptography nowadays. Privacy in contact tracing. This is a typical example of a concrete study of a contemporary scenario where one should deal with the unexpected crucial societal problem but needs not pay the cost of weakening privacy of users. Finally, we exemplify emerging notions, and in particular one aimed at reinforcing privacy by masking the type of executed protocol; we call it covert cryptographic primitives and protocols.