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GLV optimization

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This commit is contained in:
Pieter Wuille
2013-03-10 04:24:00 +01:00
parent 7ba40aa4cd
commit 949bea9262
5 changed files with 163 additions and 60 deletions
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58
group.h
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@@ -239,6 +239,8 @@ public:
cop.GetAffine(aff);
return aff.ToString();
}
void SetMulLambda(const GroupElemJac &p);
};
void GroupElem::SetJac(GroupElemJac &jac) {
@@ -260,6 +262,22 @@ static const unsigned char g_y_[] = {0x48,0x3A,0xDA,0x77,0x26,0xA3,0xC4,0x65,
0xFD,0x17,0xB4,0x48,0xA6,0x85,0x54,0x19,
0x9C,0x47,0xD0,0x8F,0xFB,0x10,0xD4,0xB8};
// properties of secp256k1's efficiently computable endomorphism
static const unsigned char lambda_[] = {0x53,0x63,0xad,0x4c,0xc0,0x5c,0x30,0xe0,
0xa5,0x26,0x1c,0x02,0x88,0x12,0x64,0x5a,
0x12,0x2e,0x22,0xea,0x20,0x81,0x66,0x78,
0xdf,0x02,0x96,0x7c,0x1b,0x23,0xbd,0x72};
static const unsigned char beta_[] = {0x7a,0xe9,0x6a,0x2b,0x65,0x7c,0x07,0x10,
0x6e,0x64,0x47,0x9e,0xac,0x34,0x34,0xe9,
0x9c,0xf0,0x49,0x75,0x12,0xf5,0x89,0x95,
0xc1,0x39,0x6c,0x28,0x71,0x95,0x01,0xee};
static const unsigned char a1b2_[] = {0x30,0x86,0xd2,0x21,0xa7,0xd4,0x6b,0xcd,
0xe8,0x6c,0x90,0xe4,0x92,0x84,0xeb,0x15};
static const unsigned char b1_[] = {0xe4,0x43,0x7e,0xd6,0x01,0x0e,0x88,0x28,
0x6f,0x54,0x7f,0xa9,0x0a,0xbf,0xe4,0xc3};
static const unsigned char a2_[] = {0x01,
0x14,0xca,0x50,0xf7,0xa8,0xe2,0xf3,0xf6,
0x57,0xc1,0x10,0x8d,0x9d,0x44,0xcf,0xd8};
class GroupConstants {
private:
Context ctx;
@@ -269,10 +287,16 @@ private:
public:
const Number order;
const GroupElem g;
const FieldElem beta;
const Number lambda, a1b2, b1, a2;
GroupConstants() : order(ctx, order_, sizeof(order_)),
g_x(g_x_), g_y(g_y_),
g(g_x,g_y) {}
g_x(g_x_), g_y(g_y_), g(g_x,g_y),
beta(beta_),
lambda(ctx, lambda_, sizeof(lambda_)),
a1b2(ctx, a1b2_, sizeof(a1b2_)),
b1(ctx, b1_, sizeof(b1_)),
a2(ctx, a2_, sizeof(a2_)) {}
};
const GroupConstants &GetGroupConst() {
@@ -280,6 +304,36 @@ const GroupConstants &GetGroupConst() {
return group_const;
}
void GroupElemJac::SetMulLambda(const GroupElemJac &p) {
FieldElem beta = GetGroupConst().beta;
*this = p;
x.SetMult(x, beta);
}
void SplitExp(Context &ctx, const Number &exp, Number &exp1, Number exp2) {
const GroupConstants &c = GetGroupConst();
Context ct(ctx);
Number bnc1(ct), bnc2(ct), bnt1(ct), bnt2(ct), bnn2(ct);
bnn2.SetNumber(c.order);
bnn2.Shift1();
bnc1.SetMult(ct, exp, c.a1b2);
bnc1.SetAdd(ct, bnc1, bnn2);
bnc1.SetDiv(ct, bnc1, c.order);
bnc2.SetMult(ct, exp, c.b1);
bnc2.SetAdd(ct, bnc2, bnn2);
bnc2.SetDiv(ct, bnc2, c.order);
bnt1.SetMult(ct, bnc1, c.a1b2);
bnt2.SetMult(ct, bnc2, c.a2);
bnt1.SetAdd(ct, bnt1, bnt2);
exp1.SetSub(ct, exp, bnt1);
bnt1.SetMult(ct, bnc1, c.b1);
bnt2.SetMult(ct, bnc2, c.a1b2);
exp2.SetSub(ct, bnt1, bnt2);
}
}
#endif