Privacy Preserving Ranked Multi-Keyword Search for Multiple Data Owners in Cloud Computing Source : IEEE Transactions on Computers , 2015 Authors :Wei Zhang, Yaping Lin, Sheng Xiao, Die Wu, Siwang Zhou Speaker : Pengxu Tian Date: 2017/09/21 In this paper, authors proposed a new authentication scheme for heterogeneous WSN. Therefore, I will introduce heterogeneous WSN later.

Outline Introduction Proposed scheme Performance analysis This is my outline First, I will introduce what is heterogeneous WSN. And then is Proposed scheme.

Introduction Background of Searchable Encryption: Cloud computing Security concern

Introduction Basic system model for Searchable Encryption Data Owner Data Users

Introduction Preliminary Bilinear map:

Proposed scheme(1/9) System model of this paper (3) (5) (6) (4) (2) (7) (5) (1) (6) (2) (4)

Proposed scheme(2/9) Notation Description The trapdoor for 𝑇 𝑊 Oi A data owner Fi The plaintext file collection of Oi Ci The ciphertext file collection of Fi W The keyword collection 𝑊 𝑖 Oi’s encrypted keyword collection of W 𝑊 The subset of W which represents queried keywords 𝑇 𝑊 The trapdoor for 𝑇 𝑊 𝑆 𝑖,𝑗,𝑡 The relevance score of tth keyword to jth file of ith data owner

Proposed scheme(3/9) Data user authentication

Proposed scheme(4/9) Keyword encryption 𝑆 𝑎 = 𝑔 𝑘 𝑎1 ⋅ 𝑘 𝑎2 ⋅ 𝑟 𝑎 𝑆 𝑎 = 𝑔 𝑘 𝑎1 ⋅ 𝑘 𝑎2 ⋅ 𝑟 𝑎 Data Owner Administration server Cloud server

Proposed scheme(5/9) Trapdoor generation 𝑆 𝑎 = 𝑔 𝑘 𝑎1 ⋅ 𝑘 𝑎2 ⋅ 𝑟 𝑎 𝑆 𝑎 = 𝑔 𝑘 𝑎1 ⋅ 𝑘 𝑎2 ⋅ 𝑟 𝑎 Data user Administration server Cloud server

Proposed scheme(6/9) Match algorithm

Proposed scheme(7/9) Ranked search

Proposed scheme(8/9) Ranking search results For the same data owner For different data owners 𝑇 𝑗,2 𝐻 𝑖 𝑖

Proposed scheme(9/9) Ranking search results

Performance analysis identity or password bytes, nonce 16 bytes, timestamp 19 bytes, hash value 20 bytes, symmetric key 16 bytes

Performance analysis identity or password bytes, nonce 16 bytes, timestamp 19 bytes, hash value 20 bytes, symmetric key 16 bytes

Thanks for attention