[cryptography] NSA IDA Cryptological Research Centers

Andy Isaacson adi at hexapodia.org
Sun Sep 29 20:10:31 EDT 2013


On Sun, Sep 29, 2013 at 09:43:54AM -0400, John Young wrote:
> http://www.ccrwest.org/
> 
> The latter's web site lists only this offering:
> 
> La Jolla Covering Repository
> 
> A (v,k,t)-covering design is a collection of k-element subsets,
> called blocks, of {1,2,...,v}, such that any t-element subset is
> contained in at least one block.  This site contains a collection of
> good (v,k,t)-coverings. Each of these coverings gives an upper bound
> for the corresponding C(v,k,t), the smallest possible number of
> blocks in such a covering design.
[snip]
> What is "covering" and how does it related to cryptology?

As is common in math, they define what they mean in the first paragraph.
To paraphrase, they're considering ways to arrange a large number of
sets of <thing>s so that a minimum number of "blocks" is used to enclose
all of the sets.

I'm not a mathematician but that looks like set theory to me.  It's the
kind of fundamental mathematical research that frequently arises when
considering some more applied problem space.  Such fundamental
approaches frequently have applications in wide-ranging fields; to
compare to a more well-documented example, the "4-color problem" first
solved in the 70s generated techniques which ended up being critical to
optimizing C compiler designs for RISC processors in the 90s.

http://en.wikipedia.org/wiki/Four_color_theorem
http://en.wikipedia.org/wiki/Register_allocation#Isomorphism_to_graph_colorability

I doubt that much can be concluded about the activities at the research
site based on their publishing one database in such a rarefied field.

-andy


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