Monday, November 13, 2006

Service-oriented security 2

Form Follows Function.

In a recent post, Bruce Schneier makes some interesting points about the relationship between Architecture and Security [via Confused of Calcutta].
  • "Security concerns have always influenced architecture."

  • "The problem is that architecture tends toward permanence, while security threats change much faster. Something that seemed a good idea when a building was designed might make little sense a century -- or even a decade -- later. But by then it's hard to undo those architectural decisions."

  • "It's dangerously shortsighted to make architectural decisions based on the threat of the moment without regard to the long-term consequences of those decisions."
  • End-to-End Process.

    In a separate post on Voting Technology and Security, Bruce Schneier describes the steps in ensuring that the result of an election properly represents the intentions of the voters.
    "Even in normal operations, each step can introduce errors. Voting accuracy, therefore, is a matter of 1) minimizing the number of steps, and 2) increasing the reliability of each step."
    Whether this is strictly true depends on the architecture of the process - whether it is a simple linear process with no redundancy or latency, or whether there is deliberate redundancy built in to provide security of the whole over and above the security of each step. Bruce himself advocates a paper audit trail, which can be used retrospectively if required to verify the accuracy of the electronic voting machines.

    Shearing Layers.

    Security management doesn't necessarily operate on the same timescale as other elements of architecture. Our appproach to service-oriented security - indeed, to SOA generally - is based on the notion of a layered architecture, in which each layer has a different rate of change. (This is based on the Shearing Layers principle (now known as the Pace Layering principle). Thus the security layer is decoupled from the core business layer, and also from the user experience layer.

    Previous Posts: Adaption and Adaptability, Business IT Alignment 2, Service-Oriented Security

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