Efficient Traceable Authorization Search System for Secure Cloud Storage

Abstract

Secure search over the encrypted remote data provides the higher priority in cloud computing to provide the assurance to the data privacy and usability. In multi-user system Fine-grained access control is important to prevent the unauthorized data usage. Sometimes the authorized user may leak the secret key for the financial benefit. Thus, tracing and revoking the malicious user who use the key improperly are need to be solved immediately. In this project an escrow free traceable attribute based multiple keywords subset search system with verifiable outsourced decryption (EF-TAMKS-VOD) was proposed. This mechanism effectively prevents the Key Generation Centre from dishonest searching and decrypting all encrypted files of users. The decryption process requires ultra-lightweight computation which is a necessary feature for energy limited devices. After the identification of malicious user, the efficient user revocation is enabled. It support the flexible number of attributes rather than the polynomial bound. The change of the query keywords order does not affect the search result. This mechanism is provably secure. This mechanism improves the efficiency and greatly reduces the computation overhead of users’ terminals.

Existing System

In Ciphertext-policy attribute-based encryption (CP-ABE), ciphertexts are associated with access policies, which do not have to contain the identities of eligible receivers, and attributes are shared by multiple users. CP-ABE is useful for providing fine-grained access control on encrypted data. However, it also has a practicality concern that a malicious user, with his attributes shared with other users, might leak his decryption privilege as a decryption blackbox, for some financial gain or other incentives, as there is little risk of getting caught. There are two types of decryption blackboxes that reflect different practical scenarios. A key-like decryption blackbox is associated with an attribute set SD and can decrypt ciphertexts with access policies satisfied by SD. A policy-specific decryption blackbox is associated with an access policy AD and can decrypt ciphertexts with AD. Policy-specific decryption blackbox has weaker decryption capacity than key-like decryption blackbox, but tracing it is deemed to be more difficult. In the preliminary version (in CCS 2013) of this paper, we proposed a new CP-ABE scheme which is adaptively traceable against key-like decryption blackbox. The scheme has sublinear overhead, which is the most efficient one to date supporting fully collusion-resistant blackbox traceability. The scheme is fully secure in the standard model, and supports any monotonic access structures. In this paper, we further show that the scheme is also selectively traceable against policy-specific decryption blackbox. Furthermore, and more importantly, we prove a general statement that if a CP-ABE scheme is (selectively) traceable against policy-specific decryption blackbox, it is also (selectively) traceable against key-like decryption blackbox, which implies that we now only need to focus on building CP-ABE schemes which are traceable against policy-specific decryption blackbox

Proposed System

In the proposed system, Traceable Attribute based Multiple keywords subset search system with Verifiable Outsourced Decryption (TAMKS-VOD). The document was encrypted into the cipher text and stored in the cloud. KGC provide the secret key for the user and monitor the user. If the key was misused by the user then KGC block the user and that users are called as revoked user. Then that blocked user list was sent to the cloud to confirm the revocation list.

Architecture

ARCHITECTURE DIAGRAM