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6 Sept 2019

NBlog Sept 6 - the CIA triad revisited

I've swapped a couple of emails this week with a colleague concerning the principles and axioms behind information risk and security, including the infamous CIA triad

According to some, information security is all about ensuring the Confidentiality, Integrity and Availability of information ... but for others, CIA is not enough, too simplistic maybe.

If we ensure the CIA
of information, does that
it is secure?

Towards the end of the last century, Donn Parker proposed a hexad, extending the CIA triad with three (or is it four?) further concepts, namely:
  • Possession or control;
  • Authenticity; and 
  • Utility. 
An example illustrating Donn's 'possession or control' concept/s would be a policeman seizing someone's computer device intending to search it for forensic evidence, then finding that the data are strongly encrypted. The police physically possess the data but, without the decryption key, are denied access to the information. So far, that's simply a case of the owner using encryption to prevent access and so prevent availability of the information to the police, thereby keeping it confidential. However, the police might yet succeed in guessing or brute-forcing the key, or exploiting a vulnerability in the encryption system (a technical integrity failure), hence the owner is currently less assured of its confidentiality than if the police did not possess the device. Assurance is another aspect of integrity

Another example concerns intellectual property: although I own and have full access to a physical book, I do not generally have full rights over the information printed within. I possess the physical expression, the storage medium, but don't have full control over the intangible intellectual property. The information is not confidential, but its availability is limited by legal and ethical controls, which I uphold because I have strong personal integrity. QED

Personally, I feel that Donn's 'authenticity' is simply an integrity property. It is one of many terms I've listed below. If something is authentic, it is true, genuine, trustworthy and not a fake or counterfeit. It can be assuredly linked to its source. These aspects all relate directly to integrity.

Similarly, Donn's 'utility' property is so close as to be practically indistinguishable from availability. In the evidence seizure example, the police currently possess the encrypted data but lacking the key or the tools and ability to decrypt it, the information remains unavailable. There are differences between the data physically stored on the storage medium and the intangible information content, sure, but I don't consider 'utility' a distinct or even useful property.

Overall, the Parkerian hexad is an interesting perspective, a worthwhile challenge that doesn't quite make the grade, for me. That it takes very specific, carefully-worded, somewhat unrealistic scenarios to illustrate and explain the 3 additional concepts, scenarios that can be readily rephrased in CIA terms, implies that the original triad is adequate. Sorry Donn, no cigar.

In its definition of information security, ISO/IEC 27000 lays out the CIA triad then notes that "In addition, other properties, such as authenticity, accountability, non-repudiation, and reliability can also be involved". As far as I'm concerned, authenticity, accountability and non-repudiation are all straightforward integrity issues (e.g. repudiation breaks the integrity of a contract, agreement, transaction, obligation or commitment), while reliability is a mix of availability and integrity. So there's no need to mention them, or imply that they are somehow more special than all the other concepts that could have been called out but aren't even mentioned ....

Integrity is a fascinatingly rich and complex concept, given that it has a bearing on aspects such as:
  • Trust and trustworthiness;
  • Dependability, reliability, confidence, 'true grit' and determination; 
  • Honesty, truthfulness, openness; 
  • Authenticity, cheating, fraud, fakery, deception, concealment …; 
  • Accuracy and precision, plus corruption and so forth; 
  • Timeliness, topicality, relevance and change; 
  • Rules and obligations, prescriptions, expectations and desires, as well as limitations and constraints; 
  • Certainty and doubt, risk, probability and consequences; 
  • Accidents, mistakes, misinterpretations and misunderstandings; 
  • Compliance and assurance, checks and balances; 
  • Consistency, verifiability, provability and disprovability, proof, evidence and fact - including non-repudiation; 
  • Social and cultural norms, conventions and ‘understandings’; 
  • Personal/individual values, ethics and morals, plus social or societal aspects such as culture and group-think; 
  • Enforcement (through penalties) and reinforcement (through awareness and encouragement) of obligations, rules, expectations etc.; 
  • Reputation, image and credibility - very important and valuable in the case of brands, for instance. 
Confidentiality is pretty straightforward, although sometimes confused with privacy.  Privacy partially overlaps confidentiality but goes further into aspects such as modesty and personal choice, such as a person's right to control disclosure and use of information about themselves.

Availability is another straightforward term with an interesting wrinkle. Securing information is as much about ensuring the continued availability of information for legitimate purposes as it is about restricting or preventing its availability to others. It's all too easy to over-do the security controls, locking down information so far that it is no longer accessible and exploitable for authorized and appropriate uses, thereby devaluing it. Naive, misguided attempts to eliminate information risk tend to end up in this sorry state. "Congratulations! You have secured my information so strongly that it's now useless. What a pointless exercise! Clear your desk: you're fired!"

Summing up, the CIA triad is a very simple and elegant expression of a rather complex and diffuse cloud of related issues and aspects. It has stood the test of time. It remains relevant and useful today. I commend it to the house.

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