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Spr2016: MAT4930 2H22, MAT6932 21BH, Number Thy & Cryptography MWF7 LIT239 (NE)
Number Theory & Mathematical Cryptography
Endofsemester NT Individual Optional Project
The
IOP (pdf),
is due, slid
u
n
d
e
r
my office door (Little Hall 402, Northeast corner)
,
no later than 4:30PM, Thur., 21Apr2016.
The project must be carefully typed,
but diagrams may be handdrawn.
At all times have a paper copy you can handin; I do
NOT accept
electronic versions.
Print out a copy each day, so that you always have the latest version to
handin; this, in case your printer or computer fails.
(You are too old for My dog ate my homework.
)
Please follow the guidelines on the
Checklist
(pdf, 3pages) to earn full credit.
 The NT/Crypto Microquizzes so far (pdf).
[Monday, 18Apr2016]
 The historicallyimportant
Meshalkin Example (pdf)
of two isomorphic Bernoulli processes, with different distributions
yet the same entropy.
Curiously, we had the chaotic
XCl (pdf),
that students accepted with good grace, since it had
been typed just minutes before the exam was given.
We had the friendly
WCl (pdf)
on Monday, 28Mar2016.
The beguiling
WHome (pdf)
now has solutions.
The intriguing VHome (pdf)
is online, for your teamsolving pleasure.
Next came the beguiling VClass (pdf)
for your posting enjoyment.
We had a pleasant
UClass
(a minitest of prerequisite knowledge)
on
Friday, 08Jan2016.
Available was a practice prereq.
Our
Teaching Page
has useful information for students in all of my classes.
It has
my schedule,
LOR guidelines,
and
Usually Useful Pamphlets.
One of them is the
Checklist (pdf)
which gives pointers on what I consider to be good mathematical
writing.
Further information is at our
classarchive URL
(I email this private URL directly to students).
In all of my courses,
attendance is absolutely required
(excepting illness and religious holidays).
In the unfortunate event that you miss a class, you are
responsible to get all
Notes / Announcements / TheWholeNineYards
from a classmate, or several.
All my classes have a
substantial
classparticipation grade.
Resources from a previous incarnation of the course
Approx. Syllabus
 A review of modular arithmetic.
 Versions of The Euclidean Algorithm (the
Lightning Bolt
alg).
 Possibly: LBolt over the Gaussian Integers.
Proving unique factorization in the Gaussian Integers. Using LBolt to write
certain primes as sumsoftwosquares.
 Euler phi function, Fermat's Little Thm.
EulerFermat Thm (EFT). The Legendre and Jacobi symbols.
 The RSA Cryptosystem.
 The Chinese Remainder Thm (CRT) and a brief introduction to Rings and Ringisomorphism.
 Huffman codes. Huffman's theorem on
minimum expected codinglength codes.
Uniquelydecodable codes and the KraftMcMillan theorem.
 Elias delta code and the ZivLempel adaptive code.
 DiffieHellman Cryptosystem.
Shank's Babystep Giantstep method for trying to break the DiffieHellman protocol.
 Pollardρ factorization algorithm.
DescentfromtheTop algorithm for computing the modM mult. order of an element.
 Possibly: Pollard's p1
factorization algorithm.
 MillerRabin algorithm. Possibly: Polytime testing whether N is a primepower.
 Multiplicative functions. Dirichlet convolution.

Possibly:
Along the way to developing cryptographic methods, we will solve a number
of Diophantine equations, that is, algebraic equations where the only
solutions that we allow are using integers.
We will find all
Pythagorean triples
(a,b,c) of positive integers for which
a^{2} + b^{2} = c^{2} .
We will discover that there is a twoparameter family of such solutions.
See Pythagorean Triples (pdf)
at
Usually Useful Pamphlets.
 Possibly: Meshalkin Isomorphism code.
ENCODING:
a b c d e f g h i j k l m n o p q r s t u v w x y z ' . ? ! ,
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Three Examples of simple ciphers:
CAESAR: Shift of 9:
a b c d e f g h i j k l m n o p q r s t u v w x y z ' . ? ! ,
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 0 1 2 3 4 5 6 7 8
MULTIPLICATIVECIPHER: Mult by 5:
a b c d e f g h i j k l m n o p q r s t u v w x y z ' . ? ! ,
0 5 10 15 20 25 30 3 8 13 18 23 28 1 6 11 16 21 26 31 4 9 14 19 24 29 2 7 12 17 22 27
AFFINECIPHER: Mult by 5, then add 9. x > [5*x]+9 (mod 32)
a b c d e f g h i j k l m n o p q r s t u v w x y z ' . ? ! ,
9 14 19 24 29 2 7 12 17 22 27 0 5 10 15 20 25 30 3 8 13 18 23 28 1 6 11 16 21 26 31 4
Various math czars who help out.
Time 
Computer/Proj 
Blackboard 
Humor 
EProblems 
Phone 
Tad 
James S. 
? 
Chris L. 
Autumn 
Austin J. 
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