41 lines
938 B
Plaintext
41 lines
938 B
Plaintext
|
# Edwards curve arithmetic
|
||
|
|
edwards_add(p,a,d, X1,Y1,Z1,T1, X2,Y2,Z2,T2, X3,Y3,Z3,T3) mod(p) {
|
||
|
|
A = X1*X2;
|
||
|
|
B = Y1*Y2;
|
||
|
|
C = d*T1*T2;
|
||
|
|
D = Z1*Z2;
|
||
|
|
E = (X1+Y1)*(X2+Y2);
|
||
|
|
E = E - A - B;
|
||
|
|
F = D - C;
|
||
|
|
G = D + C;
|
||
|
|
H = B - a*A;
|
||
|
|
X3 = E*F;
|
||
|
|
Y3 = G*H;
|
||
|
|
Z3 = F*G;
|
||
|
|
T3 = E*H;
|
||
|
|
}
|
||
|
|
edwards_sel(s, X1,Y1,Z1,T1, X2,Y2,Z2,T2, X3,Y3,Z3,T3){
|
||
|
|
X3 = s != 0 ? X1 : X2;
|
||
|
|
Y3 = s != 0 ? Y1 : Y2;
|
||
|
|
Z3 = s != 0 ? Z1 : Z2;
|
||
|
|
T3 = s != 0 ? T1 : T2;
|
||
|
|
}
|
||
|
|
edwards_new(x,y,z,t, X,Y,Z,T) {
|
||
|
|
X = x;
|
||
|
|
Y = y;
|
||
|
|
Z = z;
|
||
|
|
T = t;
|
||
|
|
}
|
||
|
|
edwards_scale(p,a,d, s, X1,Y1,Z1,T1, X3,Y3,Z3,T3) {
|
||
|
|
X2,Y2,Z2,T2 = edwards_new(X1,Y1,Z1,T1);
|
||
|
|
X4,Y4,Z4,T4 = edwards_new( 0, 1, 1, 0);
|
||
|
|
X3,Y3,Z3,T3 = edwards_sel(s % 2, X2,Y2,Z2,T2, X4,Y4,Z4,T4);
|
||
|
|
k = s >> 1; j = p >> 1;
|
||
|
|
while(j != 0){
|
||
|
|
X2,Y2,Z2,T2 = edwards_add(p,a,d, X2,Y2,Z2,T2, X2,Y2,Z2,T2);
|
||
|
|
X4,Y4,Z4,T4 = edwards_add(p,a,d, X2,Y2,Z2,T2, X3,Y3,Z3,T3);
|
||
|
|
X3,Y3,Z3,T3 = edwards_sel(k % 2, X4,Y4,Z4,T4, X3,Y3,Z3,T3);
|
||
|
|
k = k >> 1; j = j >> 1;
|
||
|
|
}
|
||
|
|
}
|