I suspect you are slightly confused about how Bell-Lapadula works, and in particular, how categories work in Bell-Lapadula.

• Classifications are necessarily ordered. In your example, we have Restricted < Confidential < Secret < Top Secret. So far, so good.

• Categories are, in general, not ordered. Often, they are a set, with no ordering amongst them. They are used for compartmentalization, and they are orthogonal to classification. A compartment is used to further restrict dissemination to a group of individuals with a need-to-know. Examples of compartments (categories) might be GAMMA (interception of Soviet communications), RUFF (images obtained by satellite), or somesuch. For instance, the set of categories might be {GAMMA, RUFF}, with no ordering implied between GAMMA vs RUFF.

A document might be stamped, e.g., Top Secret GAMMA RUFF. For someone to be allowed to read this document, they need both Top Secret clearance, and they need to be authorized to access material in the GAMMA compartment and to access material in the RUFF compartment. In general, to read some document, your clearance needs to be at least as high as the classification, and you have to be a member of every compartment (category) that the document is labelled with.

Thus, in practice, compartments would never be ranks like Lieutenant. Your example doesn't make sense.

With this background, each document / data item is labelled as follows:

• It has a classification.

• It has a set of categories (compartments).

You can represent the classification as @Jeff Ferland suggests. To represent the set of categories, you'll need to modify @Jeff's suggestion, and store a set of categories.

The most interesting part is not the representation of labels; the most interesting part is to figure out how to compare two labels. If a document has label L, and a person has label L', should the person be allowed to read the document? To check that you understand the Bell-Lapadula model, I suggest that you code up this check, for some example. I'm not going to tell you how to do it. You are asking about homework, so you should work it out for yourself -- it will be a good learning experience for you.

I suspect you are slightly confused about how Bell-Lapadula works, and in particular, how categories work in Bell-Lapadula.

• Classifications are necessarily ordered. In your example, we have Restricted < Confidential < Secret < Top Secret. So far, so good.

• Categories are, in general, not ordered. Often, they are a set, with no ordering amongst them. They are used for compartmentalization, and they are orthogonal to classification. A compartment is used to further restrict dissemination to a group of individuals with a need-to-know. Examples of compartments (categories) might be GAMMA (interception of Soviet communications), RUFF (images obtained by satellite), or somesuch. For instance, the set of categories might be {GAMMA, RUFF}, with no ordering implied between GAMMA vs RUFF.

A document might be stamped, e.g., Top Secret GAMMA RUFF. For someone to be allowed to read this document, they need both Top Secret clearance, and they need to be authorized to access material in the GAMMA compartment and to access material in the RUFF compartment. In general, to read some document, your clearance needs to be at least as high as the classification, and you have to be a member of every compartment (category) that the document is labelled with.

Thus, in practice, compartments would never be ranks like Lieutenant. Your example doesn't make sense.

With this background, each document / data item is labelled as follows:

• It has a classification.

• It has a set of categories (compartments).

You can represent the classification as @Jeff Ferland suggests. To represent the set of categories, you'll need to modify @Jeff's suggestion, and store a set of categories.

The most interesting part is not the representation of labels; the most interesting part is to figure out how to compare two labels. If a document has label L, and a person has label L', should the person be allowed to read the document? To check that you understand the Bell-Lapadula model, I suggest that you code up this check, for some example.

I suspect you are slightly confused about how Bell-Lapadula works, and in particular, how categories work in Bell-Lapadula.

• Classifications are necessarily ordered. In your example, we have Restricted < Confidential < Secret < Top Secret. So far, so good.

• Categories are, in general, not ordered. Often, they are a set, with no ordering amongst them. They are used for compartmentalization, and they are orthogonal to classification. A compartment is used to further restrict dissemination to a group of individuals with a need-to-know. Examples of compartments (categories) might be GAMMA (interception of Soviet communications), RUFF (images obtained by satellite), or somesuch. For instance, the set of categories might be {GAMMA, RUFF}, with no ordering implied between GAMMA vs RUFF.

A document might be stamped, e.g., Top Secret GAMMA. For someone to be allowed to read this document, they need both Top Secret clearance, and they need to be authorized to access material in the GAMMA compartment. In general, to read some document, your clearance needs to be at least as high as the classification, and you have to be a member of every compartment (category) that the document is labelled with.

Thus, in practice, compartments would never be ranks like Lieutenant. Your example doesn't make sense.

With this background, each document / data item is labelled as follows:

• It has a classification.

• It has a set of categories (compartments).

You can represent the classification as @Jeff Ferland suggests. To represent the set of categories, you'll need to modify @Jeff's suggestion, and store a set of categories.

The most interesting part is not the representation of labels; the most interesting part is to figure out how to compare two labels. If a document has label L, and a person has label L', should the person be allowed to read the document? To check that you understand the Bell-Lapadula model, I suggest that you code up this check, for some example. I'm not going to tell you how to do it. You are asking about homework, so you should work it out for yourself -- it will be a good learning experience for you.

I suspect you are slightly confused about how Bell-Lapadula works, and in particular, how categories work in Bell-Lapadula.

• Classifications are necessarily ordered. In your example, we have Restricted < Confidential < Secret < Top Secret. So far, so good.

• Categories are, in general, not ordered. Often, they are a set, with no ordering amongst them. They are used for compartmentalization, and they are orthogonal to classification. A compartment is used to further restrict dissemination to a group of individuals with a need-to-know. Examples of compartments (categories) might be GAMMA (interception of Soviet communications), RUFF (images obtained by satellite), or somesuch. For instance, the set of categories might be {GAMMA, RUFF}, with no ordering implied between GAMMA vs RUFF.

A document might be stamped, e.g., Top Secret GAMMA RUFF. For someone to be allowed to read this document, they need both Top Secret clearance, and they need to be authorized to access material in the GAMMA compartment and to access material in the RUFF compartment. In general, to read some document, your clearance needs to be at least as high as the classification, and you have to be a member of every compartment (category) that the document is labelled with.

Thus, in practice, compartments would never be ranks like Lieutenant. Your example doesn't make sense.

With this background, each document / data item is labelled as follows:

• It has a classification.

• It has a set of categories (compartments).

You can represent the classification as @Jeff Ferland suggests. To represent the set of categories, you'll need to modify @Jeff's suggestion, and store a set of categories.

The most interesting part is not the representation of labels; the most interesting part is to figure out how to compare two labels. If a document has label L, and a person has label L', should the person be allowed to read the document? To check that you understand the Bell-Lapadula model, I suggest that you code up this check, for some example. I'm not going to tell you how to do it. You are asking about homework, so you should work it out for yourself -- it will be a good learning experience for you.