Discrete Methods in Mathematical Informatics Lecture 1: What is Elliptic Curve? 9 th October 2012...
Transcript of Discrete Methods in Mathematical Informatics Lecture 1: What is Elliptic Curve? 9 th October 2012...
Discrete Methods in Mathematical InformaticsLecture 1: What is Elliptic Curve?
9th October 2012
Vorapong Suppakitpaisarnhttp://www-imai.is.s.u-tokyo.ac.jp/~mr_t_dtone/
[email protected], Eng. 6 Room 363Download Slide at: https://www.dropbox.com/s/xzk4dv50f4cvs18/Lecture
%201.pptx?m
First Section of This Course [5 lectures]
Lecture 1: What is
Elliptic Curve?
Lecture 2: Elliptic Curve
Cryptography
Lecture 3-4:
Fast Implementation
for Elliptic Curve Cryptography
Lecture 5: Factoring
and Primality Testing
L. C. Washington, “Elliptic Curves: Number Theory and Cryptography”, Chapman &
Hall/CRC, 2003.
• Lecture 1: Chapter 1, Chapter 2 (2.1, 2.2)
• Lecture 2: Chapter 6 (6.1 – 6.6)
• Lecture 5: Chapter 7
Recommended Reading
H. Cohen, G. Frey, R. Avanzi, C. Doche, T. Lange, K. Nguyen, F. Vercauteren, "Handbook of Elliptic and Hyperelliptic
Curve Cryptography", Chapman & Hall/CRC, 2005.
A. Cilardo, L. Coppolino, N. Mazzocca, L. Romano, "Elliptic Curve Cryptography Engineering", Proc. of IEEE Vol. 94,
No. 2, pp. 395-406 (2006).
In each lecture, 1-2 exercises will be given,
Choose 3 Problems out of them.
Submit to
before 31 Dec 2012
Grading
First Section of This Course [5 lectures]
Lecture 1: What is
Elliptic Curve?
Lecture 2: Elliptic Curve
Cryptography
Lecture 3-4:
Fast Implementation
for Elliptic Curve Cryptography
Lecture 5: Factoring
and Primality Testing
L. C. Washington, “Elliptic Curves: Number Theory and Cryptography”, Chapman &
Hall/CRC, 2003.
• Lecture 1: Chapter 1, Chapter 2 (2.1, 2.2)
• Lecture 2: Chapter 6 (6.1 – 6.6)
• Lecture 5: Chapter 7
Recommended Reading
H. Cohen, G. Frey, R. Avanzi, C. Doche, T. Lange, K. Nguyen, F. Vercauteren, "Handbook of Elliptic and Hyperelliptic
Curve Cryptography", Chapman & Hall/CRC, 2005.
A. Cilardo, L. Coppolino, N. Mazzocca, L. Romano, "Elliptic Curve Cryptography Engineering", Proc. of IEEE Vol. 94,
No. 2, pp. 395-406 (2006).
In each lecture, 1-2 exercises will be given,
Choose 3 Problems out of them.
Submit to
before 31 Dec 2012
Grading
Problem 1: The Artillerymens Dilemma (is not a) Puzzle
http://cashflowco.hubpages.com/
?
Height = 0: 0 Ball Square
Height = 1: 1 Ball Square
Height = 2: 1 + 4 = 5 Balls Not Square
Height = 3: 1 + 4 + 9 = 14 Balls Not Square
Height = 4: 1 + 4 + 9 + 16 = 30 Balls Not Square
2232222
6
1
2
1
3
1
6
121321 yxxx
)x)(x(xx...
Elliptic Curve
Problem 1: The Artillerymens Dilemma (is not a) Puzzle (cont.)
223
6
1
2
1
3
1yxxx
(0,0)
(1,1)
y = x
223
6
1
2
1
3
1xxxx
02
1
2
3 23 xxx
0)()(
0))()((23
abcxbcacabxcbax
cxbxax
a,b,c
equation the of roots
are that Suppose
solution. another is 2
1 y ,
2
1 x thatknow We
2
12
310
c
ccba
(1/2,1/2)
Problem 1: The Artillerymens Dilemma (is not a) Puzzle (cont.)
223
6
1
2
1
3
1yxxx
(0,0)
(1,1)
y = x
(1/2,1/2)
(1/2,-1/2)
y = 3x-2
223 )23(6
1
2
1
3
1 xxxx
0...2
51 23 xx
2
511
2
1 x
70,24 yx
2222 7024...21
70 Length Square for 24 Height Pyramid
Problem 2: Right Triangle with Rational Sides
We want to find a right triangle with rational sides
in which area = 5
3
4
5
6
15
8
17
60
15/2
4
17/2
155
5
510
Problem 2: Right Triangle with Rational Sides (cont.)
a
b
c
ab/2 = 5
22210 cb, aab
524
102
4
2
2
22222
ccbababa
524
102
4
2
2
22222
ccbababa
numbers rational of square are 2
c
2
c
numbers rational are
5,2
,5
2,
2,
2222
c
bacba
23 25)5()5( yxxxxx
Elliptic Curve
4
25x
num rational of square
a not is 4
5 but
curve,elliptic of
solution a is
4
45,
Note
Problem 2: Right Triangle with Rational Sides (cont.)
23 25 yxx
(-4,6)12
23
)6(2
25)4(3
2
253
2)253(
)()25(
22
2
23
y
x
x
y
yyxx
yxx
3
41)4(
12
23)6(
12
23
c
cxy3
41
12
23 xy
Problem 2: Right Triangle with Rational Sides (cont.)
23 )3
41
12
23(25 xxx
0...144
529 23 xx
0)()(
0))()((23
abcxbcacabxcbax
cxbxax
a,b,c
equation the of roots
are that Suppose
2
6
41
144
1681
144
52944
0)))(4())(4((
x
x
cxxx
23 25 yxx
(-4,6)
3
41
12
23 xy
(1681/144,62279/1728)
Problem 2: Right Triangle with Rational Sides (cont.)
22
22
22
212
49
144
24015
212
31
144
9615
212
41
bax
bax
cx
2
3,
3
206
492
12
496
312
12
316
412
12
41
ba
ba
ba
c
20/3
3/2
41/6
5
23 25 yxx
(-4,6)
3
41
12
23 xy
(1681/144,62279/1728)
Exercises
5. area withtriangle right another find to
at line tangent the Use )1728
62279,
144
1681(),( yx
Exercise 1
Exercise 2
numbers. rational of squares are
that such point a in curve the intersects
at curve this to line tangent the then , and
satisfying numbers rational are if thatShow integer. an be Let
nn,x,xx),y(x(x,y)
n,xxnxy
x, yn
11111
232 0,
Problem 3: Fermat’s Last Theorem
http://wikipedia.com/
nnn cba
a,b,c
n
that such
integers nonzero no is there
, Given 3
• Conjectured by Pierre de Fermat in Arithmetica (1637).
“I have discovered a marvellous proof to this theorem, that this margin
is too narrow to contain”
• There are more than 1,000 attempts, but
the theorem is not proved until 1995 by
Andrew Wiles.
• One of his main tools is Elliptic Curve!!!
Problem 3: Fermat’s Last Theorem (cont.)
nnn cba
a,b,c
n
that such integers nonzero no is there
, Given 3
• Fermat kindly provided the proof for the case when n = 4
2
22
2
22 )(4,
a
cbby
a
cbx
xxy 432 Elliptic Curve
By several elliptic curves techniques, Fermat found that all rational solutions of the elliptic curve are (0,0),
(2,0), (-2,0)
Formal Definitions of Elliptic Curve
0274 2332 BABAxxy when
B}AxxL|yL{(x,y)}{E(L) 32
223
6
1
2
1
3
1yxxx
(0,0)
(1,1)
y = x
(1/2,1/2)
(1/2,-1/2)
Weierstrass Equation
Elliptic Curve
.
)(),(),,(
33
33
21
2211
)y,(xQP
),y(xR
QP
Q Pxx
LEyxQyxP
3.
curve. the cut line the that
point another , point Find 2.
and point pass that line aDraw 1.
:follows as define we, If
Point Addition
)2
1,
2
1()1,1()0,0(
Formal Definitions of Elliptic Curve (cont.)
.
)(),(),,(
33
33
21
2211
)y,(xQP
),y(xR
QP
Q Pxx
LEyxQyxP
3.
curve. the cut line the that
point another , point Find 2.
and point pass that line aDraw 1.
:follows as define we, If
Point Addition
)( 11
12
12
xxmyy
xx
yym
0...
))((223
311
32
xmx
BAxxyxxm
BAxxy
212
3 xxmx
1133 )( yxxmy
Formal Definitions of Elliptic Curve (cont.)
223
6
1
2
1
3
1yxxx
x = 1/2
(1/2,1/2)
(1/2,-1/2)
QPyyxx
LEyxQyxP
, , If 2121
2211 )(),(),,(
Point Addition
,PP
)y, (xP P PQ P
),y(xR
yyxx
LEyxQyxP
33
33
221
2211
2
)(),(),,(
3.
curve. the cut
line the that point another Find 2.
P. point at curve the touching line aDraw 1.
, If 1
Point Double
1728
62279,
144
1681)6,4()6,4()6,4(2
23 25 yxx
(-4,6)
3
41
12
23 xy
(1681/144,62279/1728)
Formal Definitions of Elliptic Curve (cont.)
Point Double
)( 11 xxmyy
0...
))((223
311
32
xmx
BAxxyxxm
BAxxy
12
3 2xmx
1133 )( yxxmy
)y, (xP P PQ P
),y(xR
yyxx
LEyxQyxP
33
33
221
2211
2
)(),(),,(
3.
curve. the cut
line the that point another Find 2.
P. point at curve the touching line aDraw 1.
, If 1
y
Ax
x
ym
xAxyy
BAxxy
2
3
)3(22
2
32
First Section of This Course [5 lectures]
Lecture 1: What is
Elliptic Curve?
Lecture 2: Elliptic Curve
Cryptography
Lecture 3-4:
Fast Implementation
for Elliptic Curve Cryptography
Lecture 5: Factoring
and Primality Testing
L. C. Washington, “Elliptic Curves: Number Theory and Cryptography”, Chapman &
Hall/CRC, 2003.
• Lecture 1: Chapter 1, Chapter 2 (2.1, 2.2)
• Lecture 2: Chapter 6 (6.1 – 6.6)
• Lecture 5: Chapter 7
Recommended Reading
H. Cohen, G. Frey, R. Avanzi, C. Doche, T. Lange, K. Nguyen, F. Vercauteren, "Handbook of Elliptic and Hyperelliptic
Curve Cryptography", Chapman & Hall/CRC, 2005.
A. Cilardo, L. Coppolino, N. Mazzocca, L. Romano, "Elliptic Curve Cryptography Engineering", Proc. of IEEE Vol. 94,
No. 2, pp. 395-406 (2006).
In each lecture, 1-2 exercises will be given,
Choose 3 Problems out of them.
Submit to
before 31 Dec 2012
Grading
Exercises
5. area withtriangle right another find to
at line tangent the Use )1728
62279,
144
1681(),( yx
Exercise 1
Exercise 2
numbers. rational of squares are
that such point a in curve the intersects
at curve this to line tangent the then , and
satisfying numbers rational are if thatShow integer. an be Let
nn,x,xx),y(x(x,y)
n,xxnxy
x, yn
11111
232 0,
Scalar Multiplication• Scalar Multiplication on Elliptic Curve
S = P + P + … + P = rP
when r1 is positive integer, S,P is a member of the curve• Double-and-add method• Let r = 14 = (01110)2
Compute rP = 14P r = 14 = (0 1 1 1 0)2 Weight = 3
P 3P 7P 14P
6P2P 14P
3 – 1 = 2 Point Additions
4 – 1 = 3 Point Doubles
r times
O