IntelliGrid Architecture

Security and Security Domains

Introduction to Security Domains

There are many potential methods through which to facilitate the discussion of security.  Many desire to discuss security on an Enterprise basis.  However, there is an issue regarding the definition and boundaries of the “Enterprise” and those boundaries are always changing. Thus developing “Enterprise” level security constructs/policies becomes difficult and un-productive, as they are difficult to manage.

Another method is to perform concrete analysis of particular systems and communication technologies/topologies.  It is often difficult to discuss a security models in concrete terms since the technology used in deployments typically becomes the lowest common denominator that is discussed.  Such technology based security models tend to be difficult to scale and understand from a enterprise system perspective.  Likewise, such concrete models are difficult to extend/scale to address systemic security.

There is another, although less used, concept.  That is the concept discussing security in regards to atomic “security domains” that represent security boundaries.

“The concept of a security domain that is introduced in this paper is not new. Many computer security practitioners have been (either explicitly or implicitly) using the ideas presented here for many years in protecting networks.”[1] For instance, NERC 1200 and 1300 security requirements use the term "Electronic Perimeters" for Security Domains.

Security Domain Definition

“Telecommunications and Network Security domain encompasses the structures, transmission, methods, transport formats and security measures used to provide integrity, availability, authentication, and confidentiality for transmission over private and public communications networks and media.” [2] Additionally, “In this paper, the term Security Domain is used to describe a network of computer systems that share a specified security level through a common element.”[1].

Figure 1: Representation of Security Domain Concept[2]

A Security Domain (SD) represents a set of resources (e.g. network, computational, and physical) that is governed/secured and managed through a consistent set of security policies and processes.  Thus each Security Domain is responsible for its own general security process (e.g. Assessment, Policy, Deployment, Monitoring, and Training). In addition to the general security process, a Security Domain provides a well-known set of security functions that are used to secure transactions and information within that domain. 

Security Management of Security Domains

Security Management is defined as:  “In network management, the set of functions (a) that protects telecommunications networks and systems from unauthorized access by persons, acts, or influences and (b) that includes many subfunctions, such as creating, deleting, and controlling security services and mechanisms; distributing security-relevant information; reporting security-relevant events; controlling the distribution of cryptographic keying material; and authorizing subscriber access, rights, and privileges.”[9]  Based upon this definition, it is the Security Management of an SD that is responsible for the risk assessment, developing security policies and strategies, and implementing those policies and strategies. 

Security Functions for Security Domains

A successful Security Domain will define and implement the following security functions:

• Access Control: “The prevention of unauthorized use of a resource, including the prevention of use of a resource in an unauthorized manner.”[7]. There are generally three (3) categories of Access Control that need to be addressed within a SD: Physical; Resource; and Information.
• Trust: “In cryptology and cryptosystems, that characteristic allowing one entity to assume that a second entity will behave exactly as the first entity expects. Note: Trust may apply only for some specific function. The critical role of trust in the authentication framework is to describe the relationship between an authenticating entity and a certification authority; an authenticating entity must be certain that it can trust the certification authority to create only valid and reliable certificates. [After X.509]”[9]
• Authentication.  Trust is established via Authentication. There are two methods of authentication that are prevalent in today’s electronic systems: Role Based Authentication and Individual Authentication.
• Confidentiality: “The property that information is not made available of disclosed to unauthorized individuals, entities, or process.” [7]. There are  two (2) categories of Confidentiality that need to be addressed within a SD: Protection from un-intentional disclosure and overall protection of information.
• Integrity: “The principle that keeps information from being modified or otherwise corrupted either maliciously or accidentally.”[8]
• Security Policy: “The set of rules and practices that regulate how an organization manages, protects, and distributes sensitive equipment and information.”[8]
• Security Management Infrastructure (SMI): “(I) System elements and activities that support security policy by monitoring and controlling security services and mechanisms distributing security information and reporting security events.”[10]
• Training (as described in the general security process).

Relationship of Security Processes to Security Functions within a Security Domain

Table 1 shows that the Policy security function is a function that is required in ALL aspects of the security process.  Additionally, the table also shows that an appropriate Security Management Infrastructure needs to be deployed in order to monitor and perform re-assessment of the security system within a Security Domain.

Table 1: Relating Security Processes to Functions and Services

Relationship of Security Functions to Security Services

Going the next step, in order to actually implement the security functions within a Security Domain, several Security Services have been identified.  Table 2 shows the relationships of the Functions to the Security Services that would be used to actually implement the security function.

Table 2: Relating Security Functions to Security Services

Interrelationships between Security Services

Further, it is notable that there are inter-relationships between the services themselves. As an example, Table 3 indicates that in order to provide the Identity Mapping Service the Credential Conversion service is needed. 

Table 3: Primary Services and the additional Security Services required

Security Services Needed for Intra- and Inter-Domain Security

The combination of Table 1 through Table 3 should allow users to determine what security services need to be implemented in order to achieve a specific Security Process.  However, there are different services required for inter-domain and intra-domain exchanges. These services are shown in Table 4.

Table 4: Services needed for Intra/Inter Domain Security: m = mandatory; o = optional