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[Author] Kohei KASAMATSU(1hit)

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  • Partially Wildcarded Ciphertext-Policy Attribute-Based Encryption and Its Performance Evaluation

    Go OHTAKE  Kazuto OGAWA  Goichiro HANAOKA  Shota YAMADA  Kohei KASAMATSU  Takashi YAMAKAWA  Hideki IMAI  

     
    PAPER

      Vol:
    E100-A No:9
      Page(s):
    1846-1856

    Attribute-based encryption (ABE) enables flexible data access control based on attributes and policies. In ciphertext-policy ABE (CP-ABE), a secret key is associated with a set of attributes and a policy is associated with a ciphertext. If the set of attributes satisfies the policy, the ciphertext can be decrypted. CP-ABE can be applied to a variety of services such as access control for file sharing systems and content distribution services. However, a CP-ABE scheme usually has larger costs for encryption and decryption than conventional public-key encryption schemes due to flexible policy setting. In particular, wildcards, which mean that certain attributes are not relevant to the ciphertext policy, are not essential for a certain service. In this paper, we propose a partially wildcarded CP-ABE scheme with a lower encryption and decryption cost. In our scheme, user's attributes are separated into those requiring wildcards and those not requiring wildcards. Our scheme embodies a CP-ABE scheme with a wildcard functionality and an efficient CP-ABE scheme without wildcard functionality. We show that our scheme is provably secure under the DBDH assumption. Then, we compare our scheme with the conventional CP-ABE schemes and describe a content distribution service as an application of our scheme. Also, we implement our scheme on a PC and measure the processing time. The result shows that our scheme can reduce all of the costs for key generation, encryption, and decryption as much as possible.