Advanced Encryption Technology in a Mobile Environment (Mobile Confidential Viewing)

As smartphones and tablet devices are becoming increasingly popular, more companies are considering introducing these mobile devices to improve their style of work. However, the security issues that arise with the use of mobile devices, including the risk of confidential information being leaked and the devices being stolen or lost, are preventing the introduction of such devices in many cases. To address this problem, Fuji Xerox has developed an encryption technology called Mobile Confidential Viewing (MCV) that provides users with safe, secure, and accurate access to required information from any location, while preventing the leakage of information in the event of a security crisis.

MCV is a novel key escrow technology that distributes decryption and re-encryption keys from an electronic ticket distribution server in the form of tickets. Fig. 1 shows an overview of MCV.

First, an electronic ticket containing a decryption key and a re-encryption key is issued from the electronic ticket distribution server. The encrypted file in a mobile device will be decrypted using the decryption key contained in the electronic ticket. The ticket is set with an expiration period, and after the ticket expires, the target file will be re-encrypted using the re-encryption key. The re-encrypted file can be continuously viewed by using new tickets that are periodically updated and sent from the ticket distribution server. If the mobile device is misplaced or stolen, users can stop issuance of the tickets so that the file can no longer be decrypted, thereby ensuring safety of the contents. This encryption technology enables users to protect the data stored in mobile devices and control the time allowed for viewing each file.

Fig. 1: Overview of Mobile Confidential Viewing

Eq.1 in Fig. 2 below demonstrates the security of this encryption method under the notion of computational indistinguishability.Note1 The equation indicates that contents cannot be distinguished by only using public information, and that this method is thus highly secure.

Fig. 2: Demonstration of Security for the Encryption Method

  • Note1 Computational indistinguishability is a concept of cryptographical security that focuses on the amount of computation required for decrypting ciphertexts without secret information.