Uninformed: Informative Information for the Uninformed

Vol 7» 2007.May

Variable Elements

MPFs can yield more complex passwords by including variable elements. For example, the MPF designer can prepend the characters "p:" or "b:" to the beginning of the to include an element indicating whether the target system is a personal or business.

$\displaystyle <p\vert b>:<u>@<h\vert n>.<d\vert n>; $

To further expand this example, consider a user who performs system administration work for multiple entities. In this case the variable element being prepended could be the first letter of the system's managing entity:

$\displaystyle <x>:<u>@<hi\vert n>.<d\vert n>; $

$ <x>$ could be replaced by ``p'' for a personal system, ``E'' for a system within Exxon-Mobil's management domain, or ``A'' for a system managed by the Austin Hackers Association. Most of the elements used thus far are relatively simple variable elements that derive their value from other known contextual information such as user or system name. The contrast is that elements are capricious only in how their value changes when the MPF is applied to different systems. Variable elements change values in relation to the context of the class of access or due to a number of other factors outside the basic ``user/system'' context.

To illustrate this concept, the use of the same MPF for a super-user and an unprivileged user account on the same system may result in passwords that only differ slightly. Including a variable element can help to mitigate this similarity. Prepending the characters ``0:'' or ``1:'' to the resultant password to indicate super-user versus unprivileged user access. Respectively, by inclusion of an additional variable element in the MPF will result in the password's increased complexity as well as indicating class of access:

$\displaystyle <0\vert 1>:<u>@<h\vert n>.<d\vert n>; $

Variable elements are not required to prepend the beginning of the formula as with the examples above; they can be easily appended or inserted anywhere within the MPF.