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refactor ec::dbl

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MITSUNARI Shigeo 5 years ago
parent 9c62b3d964
commit 7e6ab212fb
3 changed files with 38 additions and 93 deletions
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  1. 108
      include/mcl/ec.hpp
  2. 17
      include/mcl/mapto_wb19.hpp
  3. 6
      test/mapto_wb19_test.cpp

108
include/mcl/ec.hpp
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@ -117,9 +117,9 @@ bool isValidJacobi(const F& x, const F& y, const F& z, const F& a, const F& b)
}
/*
a = 0 3M + 4S + 12A
a = -3 3M + 6S + 13A
generic 4M + 6S + 13A
a = 0 2M + 5S + 14A
a = -3 2M + 7S + 15A
generic 3M + 7S + 15A
*/
template<class E>
void dblJacobi(E& R, const E& P, int specialA, const typename E::Fp& a)
@ -129,87 +129,31 @@ void dblJacobi(E& R, const E& P, int specialA, const typename E::Fp& a)
R.clear();
return;
}
#if 0
// a = 0 M + 7S + 15A
// a = -3 M + 8S + 18A
// generic 2M + 8S + 16A
F x2, y2, y4, z2, s, m, t;
F::sqr(x2, P.x);
F::sqr(y2, P.y);
F::sqr(y4, y2);
const bool isPzOne = P.z.isOne();
if (isPzOne) {
z2 = P.z;
} else {
F::sqr(z2, P.z);
}
F::add(s, P.x, y2);
F::sqr(s, s);
s -= x2;
s -= y4;
s += s;
F::add(m, x2, x2);
m += x2;
switch (specialA) {
case Zero:
break;
case Minus3:
if (isPzOne) {
t = z2;
} else {
F::sqr(t, z2);
}
m -= t;
m -= t;
m -= t;
break;
case GenericA:
default:
if (isPzOne) {
m += a;
} else {
F::sqr(t, z2);
t *= a;
m += t;
}
break;
}
F::sqr(t, m);
t -= s;
F::sub(R.x, t, s); // m^2 - 2s
F::add(R.z, P.y, P.z);
F::sqr(R.z, R.z);
R.z -= y2;
R.z -= z2;
F::sub(R.y, s, R.x);
R.y *= m;
F::add(t, y4, y4);
t += t;
t += t;
R.y -= t;
#else
F S, M, t, y2;
F x2, y2, xy, t;
F::sqr(x2, P.x);
F::sqr(y2, P.y);
F::mul(S, P.x, y2);
const bool isPzOne = P.z.isOne();
S += S;
S += S;
F::sqr(M, P.x);
F::add(xy, P.x, y2);
F::sqr(y2, y2);
F::sqr(xy, xy);
xy -= x2;
xy -= y2;
xy += xy;
switch (specialA) {
case Zero:
F::add(t, M, M);
M += t;
F::add(t, x2, x2);
x2 += t;
break;
case Minus3:
if (isPzOne) {
M -= P.z;
x2 -= P.z;
} else {
F::sqr(t, P.z);
F::sqr(t, t);
M -= t;
x2 -= t;
}
F::add(t, M, M);
M += t;
F::add(t, x2, x2);
x2 += t;
break;
case GenericA:
default:
@ -220,28 +164,26 @@ void dblJacobi(E& R, const E& P, int specialA, const typename E::Fp& a)
F::sqr(t, t);
t *= a;
}
t += M;
M += M;
M += t;
t += x2;
x2 += x2;
x2 += t;
break;
}
F::sqr(R.x, M);
R.x -= S;
R.x -= S;
F::sqr(R.x, x2);
R.x -= xy;
R.x -= xy;
if (isPzOne) {
R.z = P.y;
} else {
F::mul(R.z, P.y, P.z);
}
R.z += R.z;
F::sqr(y2, y2);
F::sub(R.y, xy, R.x);
R.y *= x2;
y2 += y2;
y2 += y2;
y2 += y2;
F::sub(R.y, S, R.x);
R.y *= M;
R.y -= y2;
#endif
}
// 7M + 4S + 7A

17
include/mcl/mapto_wb19.hpp
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@ -135,14 +135,14 @@ struct MapToG2_WB19 {
R.y -= S1;
R.y -= S1;
}
// jacobi : sqr 5, mul 2, add 14
// jacobi : 2M + 5S + 14A
template<class G>
void dblT(G& Q, const G& P) const
{
#if 0
ec::dblJacobi(Q, P, ec::GenericA, Ell2p_a);
#else
Fp2 A, B, C, D, E, F;
Fp2 A, B, C, D, e, f;
Fp2::sqr(A, P.x);
Fp2::sqr(B, P.y);
Fp2::sqr(C, B);
@ -151,10 +151,10 @@ struct MapToG2_WB19 {
D -= A;
D -= C;
D += D;
Fp2::add(E, A, A);
E += A;
Fp2::sqr(F, E);
Fp2::sub(Q.x, F, D);
Fp2::add(e, A, A);
e += A;
Fp2::sqr(f, e);
Fp2::sub(Q.x, f, D);
Q.x -= D;
Fp2::mul(Q.z, P.y, P.z);
if (Q.z.isZero()) {
@ -164,7 +164,7 @@ struct MapToG2_WB19 {
}
Q.z += Q.z;
Fp2::sub(Q.y, D, Q.x);
Q.y *= E;
Q.y *= e;
C += C;
C += C;
C += C;
@ -178,6 +178,7 @@ struct MapToG2_WB19 {
void dbl(G2& Q, const G2& P) const
{
dblT(Q, P);
// G2::dbl(Q, P);
}
// P is on y^2 = x^3 + Ell2p_a x + Ell2p_b
bool isValidPoint(const Point& P) const
@ -301,6 +302,7 @@ struct MapToG2_WB19 {
// refer (xnum, xden, ynum, yden)
void iso3(G2& Q, const Point& P) const
{
// assert(isValidPoint(P));
Fp2 zpows[3];
Fp2::sqr(zpows[0], P.z);
Fp2::sqr(zpows[1], zpows[0]);
@ -321,6 +323,7 @@ struct MapToG2_WB19 {
Fp2::sqr(t, Q.z);
Fp2::mul(Q.y, mapvals[2], mapvals[1]);
Q.y *= t;
// assert(Q.isValid());
}
/*
(a+bi)*(-2-i) = (b-2a)-(a+2b)i

6
test/mapto_wb19_test.cpp
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@ -688,9 +688,9 @@ void testHashToFp2v6(const T& mapto)
Fp2 out[2];
mapto.hashToFp2v6(out, msg, strlen(msg), dst, strlen(dst));
Fp2 expect[2];
for (int i = 0; i < 2; i++) {
set(expect[i], expectStr[i]);
CYBOZU_TEST_EQUAL(out[i], expect[i]);
for (int j = 0; j < 2; j++) {
set(expect[j], expectStr[j]);
CYBOZU_TEST_EQUAL(out[j], expect[j]);
}
if (i == 0) {
// from draft-irtf-cfrg-hash-to-curve/poc/vectors/BLS12381G2_XMD:SHA-256_SSWU_RO_.json.swp

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