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working ecmult

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This commit is contained in:
Pieter Wuille
2013-03-10 01:49:42 +01:00
parent cb4d29c81e
commit 7ba40aa4cd
6 changed files with 85 additions and 42 deletions
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24
group.h
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@@ -39,10 +39,11 @@ public:
y.SetNeg(y, 1);
}
std::string ToString() {
std::string ToString() const {
if (fInfinity)
return "(inf)";
return "(" + x.ToString() + "," + y.ToString() + ")";
FieldElem xc = x, yc = y;
return "(" + xc.ToString() + "," + yc.ToString() + ")";
}
void SetJac(GroupElemJac &jac);
@@ -51,7 +52,7 @@ public:
};
/** Represents a point on the secp256k1 curve, with jacobian coordinates */
class GroupElemJac : public GroupElem {
class GroupElemJac : private GroupElem {
protected:
FieldElem z;
@@ -95,7 +96,7 @@ public:
x.SetMult(x,z2);
y.SetMult(y,z3);
z = FieldElem(1);
aff.fInfinity = false;
aff.fInfinity = fInfinity;
aff.x = x;
aff.y = y;
}
@@ -122,18 +123,19 @@ public:
/** Sets this point to be the EC double of another */
void SetDouble(const GroupElemJac &p) {
if (p.fInfinity || y.IsZero()) {
FieldElem t5 = p.y;
if (p.fInfinity || t5.IsZero()) {
fInfinity = true;
return;
}
FieldElem t1,t2,t3,t4,t5;
z.SetMult(p.y,p.z);
FieldElem t1,t2,t3,t4;
z.SetMult(t5,p.z);
z *= 2; // Z' = 2*Y*Z (2)
t1.SetSquare(p.x);
t1 *= 3; // T1 = 3*X^2 (3)
t2.SetSquare(t1); // T2 = 9*X^4 (1)
t3.SetSquare(p.y);
t3.SetSquare(t5);
t3 *= 2; // T3 = 2*Y^2 (2)
t4.SetSquare(t3);
t4 *= 2; // T4 = 8*Y^4 (2)
@@ -148,6 +150,7 @@ public:
y.SetMult(t1,t3); // Y' = 36*X^3*Y^2 - 27*X^6 (1)
t2.SetNeg(t4,2); // T2 = -8*Y^4 (3)
y += t2; // Y' = 36*X^3*Y^2 - 27*X^6 - 8*Y^4 (4)
fInfinity = false;
}
/** Sets this point to be the EC addition of two others */
@@ -230,9 +233,10 @@ public:
y += h3;
}
std::string ToString() {
std::string ToString() const {
GroupElemJac cop = *this;
GroupElem aff;
GetAffine(aff);
cop.GetAffine(aff);
return aff.ToString();
}
};