Page. 13 Cloud data share and search 口 Bob sends to alice an KeyGen email encrypted under Alice s public key 口A|ice' s email gateway wants to test whether the email contains the keyword urgent so that it 3 Trapdoor PEKS could route the email to her PDA immediately. 口 But Alice does not want the email gateway to be Gateway able to decrypther T est messages Alice YES/NO
Page . 13 Cloud Data share and search
Page. 14 Algorithm ∩s seup→(mpk,msk) UpTKGen→ uptkwi-W KeyGen→(pkrD,SkD) Reenc→CT EnC→CT Update→CT TKGen→TK Search→0/1 ReKeyGen→rkdi→ idj, wi→wi Dec→m
Page . 14 Algorithm 𝑺𝒆𝒕𝒖𝒑 → (𝒎𝒑𝒌,𝒎𝒔𝒌) 𝑼𝒑𝑻𝑲𝑮𝒆𝒏 → 𝒖𝒑𝒕𝒌𝒘𝒊→𝒘𝒋 𝑲𝒆𝒚𝑮𝒆𝒏 → (𝒑𝒌𝑰𝑫, 𝒔𝒌𝑰𝑫) 𝑹𝒆𝑬𝒏𝒄 → 𝑪𝑻 𝑬𝒏𝒄 → 𝑪𝑻 𝑼𝒑𝒅𝒂𝒕𝒆 → 𝑪𝑻 𝑻𝑲𝑮𝒆𝒏 → 𝑻𝑲 𝑺𝒆𝒂𝒓𝒄𝒉 → 𝟎/𝟏 𝑹𝒆𝑲𝒆𝒚𝑮𝒆𝒏 → 𝒓𝒌𝑰𝒅𝒊→𝒊𝒅𝒋,𝒘𝒊→𝒘𝒋 𝑫𝒆𝒄 → 𝒎
Page15 Data search phase 3. Search 2. upload 1. Key issue Bob 5. If yes Data Encryptor Data receiver Alice Bob 6. Decrypt
Page . 15 Data search phase
Page 16 keyword description update and C share 2. Upload ke 3. Update: Bob-> Alice: W1->Null M1-> Null 1. Share Alice with Bob- Alice Bcb→> Allce Alice data tagged with 4. Update: Null->w2 Bob 5. Update: Null->W2 Ali 6. Search 7. Match? Alice Alice Alic 8. If yes Cloud server
Page . 16 keyword description update and C share
Data sharing Privacy preservation allow any system user with Given either a search token or valid decryption rights of an keyword update token, a cloud encrypted data to share server does not know any his/her encrypted data to knowledge of the keyword(s) others efficiently and Given an original ciphertext or securely shared(reencrypted)ciphertext, a cloud server does not know any information of the underlying message as well as the keyword description tagged with the ciphertext
Page . Data sharing ▪ allow any system user with valid decryption rights of an encrypted data to share his/her encrypted data to others efficiently and securely ▪ Given either a search token or keyword update token, a cloud server does not know any knowledge of the keyword(s) ▪ Given an original ciphertext or shared (reencrypted) ciphertext, a cloud server does not know any information of the underlying message as well as the keyword description tagged with the ciphertext. Privacy preservation 17