Query-Biased Preview over Outsourced and Encrypted Data

Protocol 1

SecQBP protocol.

Storage:

 (1) the user U runs 𝙶𝚎𝚗1^𝑘 to generate the key 𝐾

 (2) 𝑈 runs 𝚂𝚎𝚝𝚞𝚙_𝐾(𝑑) to get the encrypted document 𝐷 and the index 𝐻,

    and sends (𝐷,𝐻) to the server S

Query:

 (1) U runs 𝚀𝚞𝚎𝚛𝚢_𝐾(𝐰) to get a token 𝑞 and sends it to S

 (2) 𝑆 runs 𝙲𝚘𝚖𝚙𝚞𝚝𝚎𝚂𝚌𝚘𝚛𝚎𝑞,𝐻 to produce the score result 𝑟, and

    sends it to U along with document identifier 𝑑

 (3) 𝑈 runs 𝙳𝚎𝚌𝚂𝚌𝚘𝚛𝚎_𝐾𝐰,𝑑,𝑟 to get the index number 𝑖 (best matched snippet)

 (4) 𝑈 runs a CPBR protocol as discussed, generates a query token 𝑡

   from 𝙲𝙿𝙱𝚁.𝚀𝚞𝚎𝚛𝚢(𝑖) and sends 𝑡 to S

 (5) 𝑆 responses with 𝑜 from 𝙲𝙿𝙱𝚁.𝚁𝚎𝚜𝚙𝚘𝚗𝚜𝚎(𝑡)

 (6) 𝑈 runs 𝙲𝙿𝙱𝚁.𝙳𝚎𝚌𝚘𝚍𝚎(𝑜) to get the encrypted snippet 𝐷_𝑖

 (7) 𝑈 runs 𝙳𝚎𝚌𝚂𝚗𝚒𝚙_𝐾𝑑(𝐷_𝑖) to get the plaintext 𝑠_𝑖