February 26, 2002
Practical Aspects of Modern Cryptography
35
Elliptic Groups
n
(x
1
,y
1
)
´
(x
2
,y
2
) = (x
3
,y
3
)
n
n
x
3
= ((3x
1
2
+A)/(2y
1
))
2
- 2x
1
n
y
3
= -y
1
+ ((3x
1
2
+A)/(2y
1
)) (x
1
- x
3
)
n
n
when x
1
= x
2
and y
1
=
y
2
¹
0