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Hot answers tagged access-control

5

Update Based on your comment, I'm not concerned so much about switch statement being inefficient as I am by the fact that the switch statement exists at all. , I think that I understand the question better now. And the answer is that you want currying to be applied on the first execution. As a quick explanation of currying, consider a mathematical ...

4

I can only hypothesize, so maybe this should only be a comment, but it's too long for the comment box. In general Stroustrup tries extremely hard to avoid adding new keywords to the language, so if he discovered that there was another way to get whatever "expressivity" writeonly might provide he would remove the keyword. My guess is that he actually couldn'...

3

first the Bell-LaPadula Model cannot capture changes over time. second, more serious problem arises when one considers that subjects in the Chinese Wall model may choose which CDs(company dataset) to access; in other words, initially a subject is free to access all objects. the Bell-LaPadula Model cannot emulate the Chinese Wall model.

3

The paper The Role Mining Problem: Finding a Minimal Descriptive Set of Roles by Jaideep Vaidya, Vijayalakshmi Atluri and Qi Guo covers the basic definitions and some variants and includes a mapping to the minimum tiling problem. This is explored in more detail in the third author's PhD thesis (found by Googling "A formal approach to the role mining problem.)...

3

The conversion between SQL access control policies and XML-specific access control models has been studied in: "Preserving SQL Access Control Policies Over Published XML Data" by G. Leighton (2009) According to the author: ... To the best of our knowledge, our work represents the first attempt to formulate an SQL-to-XML access control policy translation ...

3

I'm no expert on access control for structured data. This is a 10000-foot view. Don't assume a correlation between what my answer covers, what is scientifically interesting and what is significant in terms of deployment. Take any access control or permission mechanism and slap some angle braces around it, and you have an XML access control mechanism. It's ...

3

If the question is interpreted in the historical way (as done by Wandering Logic), then the answer can indeed by found in "Bjarne Stroustrup, The Design and Evolution of C++" in section "3.8 Constants". The readonly and writeonly qualifiers were proposed in January 1981 by Stroustrup as a modification of the C language (not of the C with classes language), ...

2

It is reasonably common nowadays that code is recompiled on occasion. For example, a JVM compiler will initially assume that some function call is not virtual (but can be proved wrong). It will then for a virtual function call generate code like "if (function implementation is what I thought it would be) then (call that implementation) else (recompile this ...

2

Unroll the loop. Instead of while true: switch on var: 1 => branch1 2 => branch2 default => branch3 replace that with an unrolled version: while true: switch on var: 1 => branch1 2 => goto loop2 default => branch3 return loop2: while true: branch2 Or, if you prefer: while true: switch on var: 1 =&...

2

Ravi S. Sandhu has given a part of a positive answer in his 1992 paper entitled Lattice-Based Enforcement of Chinese Walls (preprint). The idea is to build a lattice from the $n$ Conflict Of Interest (COI) classes defined in the Chinese Wall: elements are tuples of the form $[l_1, \ldots, l_n]$ where $l_i$ is either $\bot$ when no document from class $i$ has ...

1

The Harrison-Ruzzo-Ullman model has this form. It has principals (e.g., users) and objects (e.g., files), and a matrix that indicates which types of access each principal has for each object. It also models how the sets of access rights can evolve over time. It has no notion of hierarchy for principals or objects built into the model, but you could of ...

1

Short answer: both. My answer is based on knowledge of Unix, but as far as I know the same principle applies to Multics and Windows. Runtime permission checks are performed by the kernel in system calls (such as the call to open a file). They are based on a matrix where the subjects are processes — the kernel determines the content of the cell for the ...

1

When you speak about direct access in small amount of time that could also be logarithmic, you speak about secondary devices, so hard disks, floppys, USB flash drives, etc. When you speak about random access you mean that access time to any part of memory is constant. This is very hard to achieve with secondary devices, but easier with primary ones.

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