  Privacy Security of data in Cloud Storage is one of the main issues. Many
Frameworks and Technologies are used to preserve data security in cloud
storage. [1] Proposes a framework which includes the design of data
organization structure, the generation and management of keys, the treatment of
change of user's access right and dynamic operations of data, and the
interaction between participants. It also design an interactive protocol and an
extirpation-based key derivation algorithm, which are combined with lazy
revocation, it uses multi-tree structure and symmetric encryption to form a
privacy-preserving, efficient framework for cloud storage. [2] Proposes a
framework which design a privacy-preserving cloud storage framework in which he
designed an interaction protocol among participants, use key derivation
algorithm to generate and manage keys, use both symmetric and asymmetric
encryption to hide the sensitive data of users, and apply Bloom filter for
cipher text retrieval. A system based on this framework is realized. This paper
analyzes both the frameworks in terms of the feasibility of the frameworks,
running overhead of the system and the privacy security of the frameworks.
