Description:DESCRIPTION OF THE INVENTION
[16 ] In our scheme, we endeavor to achieve fine-grained key puncturing to enable the data owner to autonomously delete the outsourced IoT-driven data in a flexible and reliable manner, such that the cipher text of the deleted data still remains confidential against the cloud server or other adversaries even the punctured private key of the data owner is leaked. By taking the non-monotonic attribute-based encryption (NM-ABE) construction as the building block, tag-based puncturable encryption (T-PUN-ENC) allows one-tag-based data deletion. Specifically, in T-PUN-ENC, the data is encrypted under a set of tags T = {t1, . . . , td}, and an efficient Puncture algorithm, on input the current secret key SK and a tag ti, enables the data owner to generate a new secret key SK′ which can decrypt any ciphertext SK can decrypt, except for those including the tag ti . As a result, the data including the tag ti is deleted successfully and cannot be recovered in any case.

[17 ] Algorithm Constructions of P-PUN-ENC The concrete constructions of P-PUN-ENC are given as follows. • KeyGen(ξ, d ) → (PK, SK PK, SK0) This algorithm takes as input a security parameter ξ and number of tags associated with a ciphertext d, and outputs the public key PK and the initial secret key SK0. Specifically, it first generates a bilinear map e : G×G → GT , where G and GT are multiplicative cyclic groups of prime order p, and g is a generator of G. Then, it computes g1 = g α and g2 = g β with random α, β ∈ Z ∗ p . The algorithm randomly selects a degree-d polynomial q(x) with the restriction that q(0) = β, and defines Q(x) = g q(x) .

[ 18] System Operations Our scheme consists of four kinds of system operations corresponding to the algorithms in P-PUN-ENC: System Initialization by DO, Data Encryption by Dev, Data Deletion by DO, and Data Decryption by DO.

[19] System Initialization. In this phase, DO first defines a system security parameter ξ and the number of tags d that will be used to describe the IoT devices. Then, it calls the KeyGen(ξ, d) algorithm to generate the system public key PK and the initial secret key SK0. When deploying the IoT devices, DO will assign a set of tags T = {t1, . . . , td} to them and embed the corresponding public key components into them
, Claims:WE CLAIMS

1. Our Invention “A Novel Secure and Fine-grained Self-controlled Outsourced Data Deletion in Cloud-based IoT”.
2. According to claim1# the invention is to a Our Invention “To achieve reliable and instant data deletion simultaneously, puncturable encryption, a new form of tag-based public-key encryption primitive can be applied .
3. According to claim1,2# Finally, this invention provides Compared with T PUN-ENC, the invention P-PUN-ENC is clearly more flexible and practical, and has wider application foreground.
4. According to claim1,2,3# the invention is In addition, the cloud is able to use the outsourced key to partially decrypt the cipher text without breaking data confidentiality, which significantly reduces the decryption cost for the data owner.
5. According to claim1,2,3,4,# numerically analyze the storage and computation overheads of the invention scheme and conduct extensive simulations to demonstrate its efficiency.