OmniShare: Encrypted Cloud Storage for the Multi-Device Era

Research output: Contribution to journalArticle


  • Andrew Paverd
  • Sandeep Tamrakar
  • Hoang Long Nguyen
  • Praveen Pendyala
  • Thien Duc Nguyen
  • Elizabeth Stobert
  • Tommi Gröndahl

  • N. Asokan

  • Ahmad-Reza Sadeghi

Research units

  • Technische Universität Darmstadt
  • Université de Lorraine
  • INRIA Lorraine
  • CNRS
  • Swiss Federal Institute of Technology Zurich
  • University of Helsinki


Two attractive features of cloud storage services are the automatic synchronization of files between multiple client devices and the possibility to share files with other users. However, many users are concerned about the security and privacy of data stored in the cloud. Client-side encryption is an effective safeguard, but requires all client devices to have the decryption key. Current solutions derive these keys from user-chosen passwords, which are easily guessed. We present OmniShare, the first scheme to combine strong client-side encryption with intuitive key distribution mechanisms to enable access from multiple client devices and sharing between users. OmniShare uses a novel combination of out-of-band channels, including QR codes and ultrasonic communication, as well as the cloud storage service itself, to authenticate new devices. We describe the design and implementation of OmniShare, and explain how we evaluated its security (using formal methods), its performance (benchmarks), and its usability (cognitive walkthrough).


Original languageEnglish
Pages (from-to)27-36
Issue number4
Early online date2018
Publication statusPublished - 1 Aug 2018
MoE publication typeA1 Journal article-refereed

    Research areas

  • software, software engineering, operating systems, security and privacy protection, access controls, network-level security and protection, general, communication, networking and information technology, computing milieux, management of computing and information systems, miscellaneous, security

ID: 18559069