Security Models: Part 4 - Biba Integrity Model
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>> After talking about the Bell-LaPadula model,
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we're going to move on to the Biba Integrity Model.
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Now I want you to notice,
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integrity is different than confidentiality.
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The Bell-LaPadula has one approach
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because their goal is confidentiality,
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Biba as a security model has
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a totally different approach because
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they're focused on integrity.
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Let's look at this. As a matter of fact,
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I always tell people,
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if Bell-LaPadula makes sense to you,
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great, we're just going to reverse it in Biba.
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Everybody looks at me and says "That makes no sense",
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but it actually does,
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hang with me for a minute.
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When we talk about integrity of data,
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what we're talking about doing is protecting
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the sanctity of knowledge,
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protecting the knowledge base.
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Making sure the knowledge base is pure and has integrity.
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As a matter of fact, you can sum up
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the Biba Integrity Model with three words,
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and those three words are down data's dirty.
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Let's see how this works.
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Just like Bell-LaPadula,
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Biba is made up of rules,
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and there are three basic rules with Biba.
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We see this simple and we see the star again.
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Remember, simple properties
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and axioms are always about read.
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Star properties and axioms are always about write.
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The simple integrity axioms is no read down.
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A subject can't read to
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a lower level than they are where they exist.
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Can I read up?
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Not only can I read up,
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it's encouraged that I read above my level.
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What? Let go of thinking about confidentiality.
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Let go of thinking about protecting secrets.
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If I want to improve my knowledge,
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if I want to improve my understanding,
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I will go to more trusted sources.
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I will not go to less trusted sources.
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Let me give you an example.
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In a particularly dark period
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of my life I'm not proud about,
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I watched the television show, Honey Boo Boo.
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That's an old TV show,
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but because it left such a mark,
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I'm hoping many of you remember this,
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but it was the story of
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a child beauty queen pageant who lived in West Virginia,
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and had a very interesting life.
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I was watching this one episode,
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and these folks were really from
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the boondocks and really
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had their own way of doing things.
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One episode, the only episode I watched by the way,
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they made dinner with spaghetti, ketchup and butter.
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That was the sauce for the spaghetti.
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[NOISE] If I get
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my cooking knowledge from
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Honey Boo Boo, we're in trouble.
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I'm no longer making a decent meal.
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That's a less trusted entity.
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But if I'm baking a cake,
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and I watch the British Baking Show,
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they're much more knowledgeable on that show than I am.
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I'm going to learn,
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we're going to keep our knowledge base clean,
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and we're even going to increase
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our knowledge base if we'd read up.
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You could also think about it
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as maybe I'm a college student,
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and I go to the library,
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and they don't want me looking at
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freshmen books because maybe
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they're too simple, they're more simplified.
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If I'm a senior, they want me to look at
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senior level and grad student level books.
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I'm going to improve my knowledge.
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So Biba makes perfect sense if
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you think about it in terms of academia.
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No read down, because down data's dirty.
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I'm not going to protect the sanctity of knowledge
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if I'm getting information from less trusted sources.
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The star integrity axiom says no write up.
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You know why? Because I'll
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pollute somebody else's knowledge base.
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Never does Paul Hollywood
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on the British Baking Show call me and say,
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"Kelly, I'd like you to write
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the recipe for our next challenge."
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Why? Because I'll mess it up.
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I'll have some recipe like pepperoni pizza on there,
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which is not with the keeping of the show.
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The bottom line is, we're protecting knowledge.
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I don't read less trusted sources,
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and because I could be a less trusted source,
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I don't right above my level.
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That's the star integrity axiom.
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The invocation property says,
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no read or write above.
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You can do what you want below,
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but you can't modify what's above or read it.
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Remember, like we talked about with Bell-LaPadula,
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if the rule doesn't
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specifically restrict an action, you can perform it.
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With the simple integrity axiom,
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I can read above my level.
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Remember, this isn't about protecting secrets,
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this is about knowledge,
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it's about me learning,
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so I can go to more trusted sources.
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The star integrity axiom says no write up,
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but I can write down.
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I could read up,
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I could read down if that's the only axiom I apply.
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Again, I want to stress to you,
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most likely you're going to need
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to apply multiple axioms.
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In the real world,
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you're not sitting there thinking,
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"Oh, let me go back and review the Biba security model."
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But these are just thought processes
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that you take that are based on
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models created by engineers
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back in the day and mathematicians.
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We're not worried about
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the detailed and complex math that's
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built into a system to make this happen,
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we're just worried about the general purpose and rules.
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Quickly, we have our friend Tavera again, and Tavera,
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if you remember from the last section on Bell-LaPadula,
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Tavera has confidential clearance.
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According to Biba's star integrity axiom,
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to which files can Tavera write?
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It's written in the stars,
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and Biba says no write up
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so I don't pollute somebody else's knowledge base.
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I cannot write to file A or B, can't write up.
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I can write to my own level,
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and I can write lower.
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Then the next question according to
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Biba's simple integrity axiom,
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where can Tavera write?
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Well, anywhere, because
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the simple integrity axiom has
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nothing to do with write, it's strictly read.
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Man, I got to tell you the truth,
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that's a great way to ask
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a Biba or Bell-LaPadula question.
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That's why I put it on here.
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Make sure that these makes sense to you.
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Just to wrap up, we talked about
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the Biba Integrity Model,
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and we talked about the fact that down data's dirty.
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Biba is all about
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protecting our knowledge base and making
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sure that we don't get subjected to misinformation,
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that we don't pollute the knowledge base.
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Very different from Bell-LaPadula.
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Bell-LaPadula was confidentiality, Biba is integrity.
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