Cryptology ePrint Archive: Report 2015/150

Insynd: Privacy-Preserving Transparency Logging Using Balloons

Tobias Pulls and Roel Peeters

Abstract: Insynd is a cryptographic scheme for privacy-preserving transparency logging. In the setting of transparency logging, a service provider continuously logs descriptions of its data processing on its users' personal data, where each description is intended for a particular user. Our work focuses on protecting the privacy of users. Insynd provides secrecy of messages, message integrity and authenticity, protection against recipient profiling, and publicly verifiable proofs of who sent what message to which recipient at what particular time. Our scheme is built on an authenticated data structure (Balloon) that enables the safe outsourcing of storage of messages to an untrusted server (such as commodity cloud services). The author of messages is in the forward-security model. Insynd provides stronger privacy protections than prior work in this setting, improved efficiency in terms of event generation, and increases the utility of all data sent through the scheme thanks to the publicly verifiable proofs. Our prototype implementation shows greatly improved performance over related work and competitive performance for more data-intensive settings like secure logging.

Category / Keywords: cryptographic protocols

Date: received 23 Feb 2015, last revised 16 May 2015

Contact author: tobias pulls at kau se

Available format(s): PDF | BibTeX Citation

Version: 20150516:201209 (All versions of this report)

Short URL: ia.cr/2015/150

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