Re: How far is the NSA ahead of the public crypto community?

2008-05-09 Thread Leichter, Jerry
An interesting datapoint I've always had on this question:  Back in 1975
or so, a mathematician I knew (actually, he was a friend's PhD advisor)
left academia to go work for the NSA.  Obviously, he couldn't say
anything at all about what he would be doing.

The guy's specialty was algebraic geometry - a hot field at the time.
This is the area of mathematics that studied eliptic curves many years
before anyone realized they had any application to cryptography.  In
fact, it would be years before anyone on the outside could make any
kind of guess about what in the world the NSA would want a specialist
in algebraic geometry to do.  At the time, it was one of the purest
of the pure fields.

The friend he used to advise bumped into this guy a few years later
at a math conference.  He asked him how it felt not to be able to
publish openly.  The response:  When I was working at the university,
there were maybe 30 specialists in the world who read and understood
my papers.  There aren't quite as many now, but they really appreciate
what I do.
-- Jerry


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Re: How far is the NSA ahead of the public crypto community?

2008-05-09 Thread Matt Blaze


On May 8, 2008, at 19:08, Leichter, Jerry wrote:
An interesting datapoint I've always had on this question:  Back in  
1975
or so, a mathematician I knew (actually, he was a friend's PhD  
advisor)

left academia to go work for the NSA.  Obviously, he couldn't say
anything at all about what he would be doing.

The guy's specialty was algebraic geometry - a hot field at the time.
This is the area of mathematics that studied eliptic curves many years
before anyone realized they had any application to cryptography.  In
fact, it would be years before anyone on the outside could make any
kind of guess about what in the world the NSA would want a specialist
in algebraic geometry to do.  At the time, it was one of the purest
of the pure fields.



I've heard similar recollections of mathematicians from improbably
abstract specialties being eagerly taken in by NSA, throughout the
cold war.   I've also heard it said that at one time NSA was the
US's single largest employer of math PhDs.  I don't know if that
was actually true, but it certainly seems plausible.

But it's also important to remember that crypto isn't the only
area of the NSA mission that benefits from mathematical expertise.
I suspect that while many of these NSA math PhDs were indeed doing
cryptomathematics, a large fraction were (and are) working on
other SIGINT problems such as signal processing, databases and
searching, coding theory, machine learning, and so.  Some of the
(non-crypto) problems here seem rather specific to the NSA's domain,
and so don't likely have an advanced civilian research community
competing with them they way academic crypto does today.

A couple of the papers from the 1970's hint (in redacted form,
frustratingly)  that the NSA then had large scale automatic systems
for intercepting and processing morse code signals from large
blocks of radio spectrum, which implies some pretty advanced
(for that era) signal processing and computing, crypto aside.

-matt

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Re: How far is the NSA ahead of the public crypto community?

2008-05-09 Thread Sampo Syreeni

On 2008-05-09, Matt Blaze wrote:

The guy's specialty was algebraic geometry - a hot field at the time. 
This is the area of mathematics that studied eliptic curves many 
years before anyone realized they had any application to 
cryptography. [...]


I've heard similar recollections of mathematicians from improbably 
abstract specialties being eagerly taken in by NSA, throughout the 
cold war.


I wouldn't say algebraic geometry is such a pure and abstract specialty 
in this context. It has its roots firmly planted in multivariate 
polynomial algebra, and even at that time it was quite clearly the field 
that was most intimately connected with mechanistic solutions to groups 
of nonlinear polynomial equations over finite fields. Which then is 
exactly what a mathematician sees when presented with a symmetric 
cryptosystem to break. As evidence of that, Hilbert's basis theorem 
(which underlies Groebner bases, which in case relinearization and the 
bunch are an independently discovered special case of) was well known 
and appreciated at that time.


So, even if elliptic curve cryptography became later, the broader theory 
of algebraic geometry was *certainly* relevant to crypto even then, and 
should have easily been seen to be so.


Some of the (non-crypto) problems here seem rather specific to the 
NSA's domain, and so don't likely have an advanced civilian research 
community competing with them they way academic crypto does today.


Quite so. I think this is where one should be seeking for the signs of 
differential advantage. Not the broad fields of mathematical expertise 
which plausibly could have been acquired by the NSA for any of a number 
of reasons.


A couple of the papers from the 1970's hint (in redacted form, 
frustratingly) that the NSA then had large scale automatic systems for 
intercepting and processing morse code signals from large blocks of 
radio spectrum, which implies some pretty advanced (for that era) 
signal processing and computing, crypto aside.


Band agnostic, keying rate adaptable and error tolerant algorithms in 
this department most likely fall in the advanced category even today, 
especially if computationally thrifty. I've certainly never seen 
anything of the sort in what DSP literature I'm aware of.

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Sampo Syreeni, aka decoy - mailto:[EMAIL PROTECTED], tel:+358-50-5756111
student/math+cs/helsinki university, http://www.iki.fi/~decoy/front
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