Abstract: Cloud comp ting's multi-tenancy feature, which provides privacy, security and access control challenges, because of sharing of physical resources among untrusted tenets. In order to achieve safe storage, policy based file access control, poly based file assured delectation and policy based renewal of a file stored in a cloud environment. a suitable encryption technique with key management should be applied before outsourcing the data. Exciting system attribute based encryption is new cryptographic primitive which provides a promising tool for addressing the problem of secure and fine-grained data sharing and decentralized access control. key policy attribute based encryption (KP-ABE) is an important type of ABE, which enable senders to encrypt message under a set of attribute and private keys are associated with access structure that specify which cipher texts the key holder will be allowed to decrypt. in this paper (ABS) attribute based signature new algorithm can be easily implemented and greatly raise the computational efficiency of original ABS algorithm. a verifier will be convinced of the fact that whether the signer's attribute satisfy the predicate while remaining completely ignorant of the identity of signer.ABS is much useful in a wide range of application including private access control for ad hoc networks, attribute based messaging, etc.

Keywords: Attribute based signature, Cloud storage, Cloud service provider, Data owner, Encryption.