ZZn6 line(ECn3& A,ECn3& C,ECn3& B,int type,ZZn3& slope,ZZn3& ex1,ZZn3& ex2,ZZn& Px,ZZn& Py)
{
ZZn6 w;
ZZn3 d;
#ifdef AFFINE
ZZn3 x,y;
A.get(x,y);
d.set1(Py);
w=shuffle(y-slope*(Px+x),d);
#endif
#ifdef PROJECTIVE
ZZn3 x,y,z,z3,t;
C.getZ(z3);
d.set1(Py);
if (type==MR_ADD)
{ // exploit that B is in affine
ZZn3 x2,y2;
B.get(x2,y2);
y2*=z3; d*=z3;
w=shuffle(y2-slope*(Px+x2),d);
}
if (type==MR_DOUBLE)
{ // use extra information from point doubling
A.get(x,y,z);
w=shuffle(ex1-slope*(Px*ex2+x),d*z3*ex2);
}
#endif
return w;
}
ZZn6 gp(ZZn3* ptable,int &j,ZZn& Px,ZZn& Py)
{
ZZn6 w;
ZZn3 d;
d.set1(Py);
w=shuffle(ptable[j]*Px+ptable[j+1],d);
j+=2;
return w;
}
ZZn3 txd(const ZZn3& w)
{
ZZn3 u;
ZZn wa,wb,wc;
w.get(wa,wb,wc);
u.set(wb,wc,(wa/get_mip()->cnr));
return u;
}
void unshuffle(ZZn6 &S,ZZn3 &first,ZZn3 &second)
{ // unshuffle a ZZn6 into two ZZn3's
ZZn x0,x1,x2,x3,x4,x5;
ZZn2 t0,t1,t2;
S.get(t0,t1,t2);
t0.get(x0,x3);
t1.get(x1,x4);
t2.get(x2,x5);
first.set(x0,x2,x4);
second.set(x1,x3,x5);
}
ZZn6 shuffle(ZZn3 &first, ZZn3 &second)
{ // shuffle from a pair ZZn3's to three ZZn2's, as required by ZZn6
ZZn6 w;
ZZn x0,x1,x2,x3,x4,x5;
ZZn2 t0,t1,t2;
first.get(x0,x2,x4);
second.get(x1,x3,x5);
t0.set(x0,x3);
t1.set(x1,x4);
t2.set(x2,x5);
w.set(t0,t1,t2);
return w;
}
void PFC::hash_and_map(G2& w,char *ID)
{
int i;
ZZn3 XX;
Big X=*x;
Big x0=H1(ID);
forever
{
x0+=1;
XX.set((ZZn)0,(ZZn)x0,(ZZn)0);
if (!w.g.set(XX)) continue;
break;
}
w.g=HashG2(w.g,X,*frob);
}
void PFC::random(G2& w)
{
int i;
ZZn3 XX;
Big X=*x;
Big x0=rand(*mod);
forever
{
x0+=1;
XX.set2((ZZn)x0);
if (!w.g.set(XX)) continue;
break;
}
map(w.g,X,*frob);
}
ECn3 hash_and_map3(char *ID)
{
int i;
ECn3 S;
ZZn3 X;
Big x0=H1(ID);
forever
{
x0+=1;
X.set((ZZn)0,(ZZn)x0,(ZZn)0);
if (!S.set(X)) continue;
break;
}
return S;
}
void PFC::random(G2 &w)
{
int i;
ZZn3 XX;
Big X=*x;
Big x0=rand(*mod);
forever
{
x0+=1;
XX.set((ZZn)0,(ZZn)x0,(ZZn)0);
if (!w.g.set(X)) continue;
break;
}
w.g=HashG2(w.g,X,*frob);
}
BOOL ECn3::set(const ZZn3& xx)
{
ZZn3 w;
w=rhs(xx);
if (!w.iszero())
{
w=sqrt(w);
if (w.iszero()) return FALSE;
}
x=xx;
y=w;
marker=MR_EPOINT_NORMALIZED;
return TRUE;
}
ECn3 hash_and_map3(char *ID)
{
int i;
ECn3 S;
ZZn3 X;
Big x0=H1(ID);
forever
{
x0+=1;
X.set2((ZZn)x0);
if (!S.set(X)) continue;
break;
}
// cout << "S= " << S << endl;
return S;
}