Cloud storage is an important service of cloud computing, which offers
service for data owners to host their data in the cloud. This new
paradigm of data hosting and data access services introduces two major
security concerns. The first is the protection of data integrity. Data
owners may not fully trust the cloud server and worry that data stored
in the cloud could be corrupted or even removed. The second is data
access control. Data owners may worry that some dishonest servers
provide data access to users that are not permitted for profit gain and
thus they can no longer rely on the servers for access control.
To protect the data integrity in the cloud, an efficient and secure
dynamic auditing protocol is introduced, which can support dynamic
auditing and batch auditing. To ensure the data security in the cloud,
two efficient and secure data access control schemes are introduced in
this brief: ABAC for Single-authority Systems and DAC-MACS for
Multi-authority Systems. While Ciphertext-Policy Attribute-based
Encryption (CP-ABE) is a promising technique for access control of
encrypted data, the existing schemes cannot be directly applied to data
access control for cloud storage systems because of the attribute
revocation problem. To solve the attribute revocation problem, new
Revocable CP-ABE methods are proposed in both ABAC and DAC-MACS.