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Efficient Usage of Cover Free Families in Broadcast Encryption
Maki YOSHIDA Toru FUJIWARA
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2016/06/01
Online ISSN: 1745-1337
Type of Manuscript: PAPER
Category: Cryptography and Information Security
cover free family, efficiency, broadcast encryption, upper bound,
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A cover free family (CFF) is a useful mathematical tool for cryptographic schemes where any pre-defined number of sets in the family do not cover another set in the family. The common disadvantage of CFF-based schemes is the requirement for a significantly large amount of data such as public keys and ciphertexts. This paper proposes a simple method to reduce the size of ciphertexts in CFF-based broadcast encryption schemes by removing redundant elements from sets in the family, and then analyzes the size of cihpertexts. As a result, in a typical distribution case, the average amount of ciphertexts is reduced to 83 percents (from 691Kbits to 576Kbits).