To make integrated broadcast-broadband services secure and reliable, we researched cryptography and security technologies.

■Cryptography system for database access control

  In a service taking advantage of the linkage between cars, mobile devices and TV, the user can receive personalized content in accordance with their preference and location by giving service providers their preference and location information. For such services, we previously developed a cryptography system that allows the user to receive recommended information while keeping their preference and location information closed to any entity. In FY 2018, we conducted a security analysis and implementation evaluation on this system and confirmed that it has high security and causes no major delay that affect the service⁽¹⁾. To bring about a benefit also to data service providers, we proposed a mechanism for providing service providers whose data was used by users with user identifiers such as email address⁽²⁾.

■Cryptography algorithm for hybrid services

  To provide more advanced convergence services of broadcasting and telecommunications, we researched cryptography technologies that can be used to provide secure and reliable services.
  We previously developed a cryptography algorithm that can provide access control by specifying the attributes of providers who can access viewer information when the information is stored on the cloud. We compared the security and efficiency of this algorithm and other cryptography algorithms and demonstrated the effectiveness of our proposed system⁽³⁾.

■Post-quantum cryptography algorithm

  We researched a cryptography algorithm that can maintain security even when quantum computers are put into practical use.
  We developed a multi-party computation method for a hash function for generating a secret key and symmetric encryption for encrypting data. This method inputs multiple pieces of divided data (shares) generated from the data to be encrypted using a method called secret sharing into multiple computers and combines the results of individual calculations on each computer to generate one ciphertext as an output. With this method, the original data cannot be reconstructed from individual shares, meaning that the tolerance to quantum computers can be achieved. We extended our broadcasting service using this algorithm and developed a broadcasting system that can allow users to take out their secret key and that can protect privacy information even when quantum computers are put into practical use⁽⁴⁾.

■Watermarking algorithm for HEVC-compressed streams

  For copyright protection of content, we researched a watermarking technology that can embed the receiver’s identity into broadcast compressed content.
  We studied the computational complexity and security of the embedding method for HEVC-compressed streams that we developed previously and confirmed its effectiveness⁽⁵⁾.

 

[References]
(1)	K. Kajita, K. Ogawa and G. Ohtake: "Security analysis and Implementation on the System using VABKS on IBB Service," ITE Annual Convention 2018, 14D-1 (2018) (in Japanese)
(2)	K. Kajita, K. Ogawa and G. Ohtake: "For Realization of IBB Services – Privacy Preserving System considering Provider’s merits," SCIS2019, 1C2-3 (2019) (in Japanese)
(3)	N. Attrapadung, G. Hanaoka, K. Ogawa, G. Ohtake, H. Watanabe and S. Yamada: "Attribute-Based Encryption for Range Attributes," IEICE Trans. on Fundamentals of Electronics, Communication and Computer Science, Vol.E101-A, No.9 2018, pp.1440-1455 (2018)
(4)	K. Ogawa and K. Nuida: "MPC: Improvement of Broadcasting Services," SCIS2019, 1C2-2 (2019) (in Japanese)
(5)	K. Ogawa and G. Ohtake: "Efficient Watermarking scheme for Traitor Tracing Encryption Schemes," Journal of Electrical Engineering, Vol.6, No.5, pp. 245-255 (2018)