Page 747 - Cloud computing: From paradigm to operation

XaaS 3

8.1.1.3 Access management

SaaS application environment administrators are required to provide mechanisms, which delegate
authorization to tenants' administrators. The tenants' administrators grant access rights to their
corresponding resources. The access management of such a SaaS application environment should support
multiple access control models, such as identity based model, strategy based model, role based model, task
based model, etc.

For custom and configurable level SaaS applications, a role-based access control model is a basic
requirement. For instance, CSN, which supports to build a service from CSP, may be in charge of some
applications but has no rights to administer the whole cloud service system. Besides, CSN may be allowed to
access only a part of the resources with granted access rights. However, CSN can share its resource by
providing application interfaces to other CSNs.
For the multi-tenant and scalable level, an integration of access control model for each individual and group
is needed. For the role-based access control, shared resources among multiple tenants should be utilized
according to task groups in a work flow and rights granted to those tasks. Thus, when these task groups are
executed, the SaaS application environment should define the support task-based access control mechanism.
This mechanism is used to make sure that access right of tenants to underlying resources could be timely
granted and revoked, and underlying resources are prevented from unauthorized utilization.

8.1.2 Interface security

The SaaS application environment is required to secure interfaces open to CSPs or CSNs through which
various kinds of cloud computing services are delivered or developed, and it is also required to secure
communications based on these interfaces. Mechanisms that are available to ensure interface security
include but are not limited to: unilateral/mutual authentication, integrity checksum, digital signature, etc.
8.1.3 Data security

8.1.3.1 Data isolation
Data can be isolated physically or logically. Physical data isolation should be accomplished by the access
control of physical storages. It should require the SaaS application environment to store data of different
tenants in different areas of physical storage, or implement the data accesses control for different tenants
through access permission, data domain or any other methods. Logical data isolation implies that different
tenants should be avoided to access others' data by the means of techniques such as virtualization, even if
all the data are stored together.
For custom and configurable level SaaS applications, each tenant's data are separately stored and isolated
from the others at the physical level.
For multi-tenant and scalable level SaaS applications, all tenant's data are stored in the cloud. Therefore, the
SaaS application environment is required to be intelligent enough to segregate data from different tenants,
and maintain isolation among different tenants' data at rest, at processing or at transmission. The boundary
between each tenant should be ensured at the physical level or at the logical level, which depends on the
required isolation granularity and the specific deployment of the cloud computing software and hardware.

8.1.3.2 Data confidentiality
In most cases, the tenant's data is on off-premise storage and utilization, and is subjected to exposure.
Therefore, the SaaS application environment is required to support encryption mechanisms to ensure data
confidentiality in transmission, during processing or out of occupation, and prevent data leakage due to
security vulnerabilities in the application.

Data encryption service is required for all SaaS levels. Critical data is required to be encrypted to prevent
exposure.

For multi-tenant and scalable level, as tenants' data should be stored in one database or even one big table,
the SaaS application environment is required to provide an appropriate key management mechanism to
ensure that the data cannot be cracked by other tenants.

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