/* this/=2 mod Modulus */
public void div2()
{
x.norm();
if (x.parity() == 0)
{
x.fshr(1);
}
else
{
x.add(p);
x.norm();
x.fshr(1);
}
}
/* divide this by m */
public virtual void div(BIG m)
{
int k = 0;
norm();
BIG e = new BIG(1);
BIG b = new BIG(this);
zero();
while (comp(b, m) >= 0)
{
e.fshl(1);
m.fshl(1);
k++;
}
while (k > 0)
{
m.fshr(1);
e.fshr(1);
if (comp(b, m) >= 0)
{
add(e);
norm();
b.sub(m);
b.norm();
}
k--;
}
}
/* reduce this mod m */
public virtual void mod(BIG m)
{
int k = 0;
norm();
if (comp(this, m) < 0)
{
return;
}
do
{
m.fshl(1);
k++;
} while (comp(this, m) >= 0);
while (k > 0)
{
m.fshr(1);
if (comp(this, m) >= 0)
{
sub(m);
norm();
}
k--;
}
}
/* return this^e mod m */
public virtual BIG powmod(BIG e, BIG m)
{
int bt;
norm();
e.norm();
BIG a = new BIG(1);
BIG z = new BIG(e);
BIG s = new BIG(this);
while (true)
{
bt = z.parity();
z.fshr(1);
if (bt == 1)
{
a = modmul(a, s, m);
}
if (z.iszilch())
{
break;
}
s = modsqr(s, m);
}
return(a);
}
/* this=this^e */
public FP12 pow(BIG e)
{
norm();
e.norm();
FP12 w = new FP12(this);
BIG z = new BIG(e);
FP12 r = new FP12(1);
while (true)
{
int bt = z.parity();
z.fshr(1);
if (bt == 1)
{
r.mul(w);
}
if (z.iszilch())
{
break;
}
w.usqr();
}
r.reduce();
return(r);
}
/* return this^e mod Modulus */
public FP pow(BIG e)
{
int bt;
FP r = new FP(1);
e.norm();
x.norm();
FP m = new FP(this);
while (true)
{
bt = e.parity();
e.fshr(1);
if (bt == 1)
{
r.mul(m);
}
if (e.iszilch())
{
break;
}
m.sqr();
}
r.x.mod(p);
return(r);
}
/* r=x^n using XTR method on traces of FP12s */
public FP4 xtr_pow(BIG n)
{
FP4 a = new FP4(3);
FP4 b = new FP4(this);
FP4 c = new FP4(b);
c.xtr_D();
FP4 t = new FP4(0);
FP4 r = new FP4(0);
n.norm();
int par = n.parity();
BIG v = new BIG(n);
v.fshr(1);
if (par == 0)
{
v.dec(1);
v.norm();
}
int nb = v.nbits();
for (int i = nb - 1; i >= 0; i--)
{
if (v.bit(i) != 1)
{
t.copy(b);
conj();
c.conj();
b.xtr_A(a, this, c);
conj();
c.copy(t);
c.xtr_D();
a.xtr_D();
}
else
{
t.copy(a);
t.conj();
a.copy(b);
a.xtr_D();
b.xtr_A(c, this, t);
c.xtr_D();
}
}
if (par == 0)
{
r.copy(c);
}
else
{
r.copy(b);
}
r.reduce();
return(r);
}
/* convert this BIG to byte array */
public virtual void tobytearray(sbyte[] b, int n)
{
norm();
BIG c = new BIG(this);
for (int i = ROM.MODBYTES - 1; i >= 0; i--)
{
b[i + n] = (sbyte)c.w[0];
c.fshr(8);
}
}
/* return e.this */
public ECP mul(BIG e)
{
if (e.iszilch() || is_infinity())
{
return(new ECP());
}
ECP P = new ECP();
if (ROM.CURVETYPE == ROM.MONTGOMERY)
{
/* use Ladder */
int nb, i, b;
ECP D = new ECP();
ECP R0 = new ECP();
R0.copy(this);
ECP R1 = new ECP();
R1.copy(this);
R1.dbl();
D.copy(this);
D.affine();
nb = e.nbits();
for (i = nb - 2; i >= 0; i--)
{
b = e.bit(i);
P.copy(R1);
P.dadd(R0, D);
R0.cswap(R1, b);
R1.copy(P);
R0.dbl();
R0.cswap(R1, b);
}
P.copy(R0);
}
else
{
// fixed size windows
int i, b, nb, m, s, ns;
BIG mt = new BIG();
BIG t = new BIG();
ECP Q = new ECP();
ECP C = new ECP();
ECP[] W = new ECP[8];
sbyte[] w = new sbyte[1 + (ROM.NLEN * ROM.BASEBITS + 3) / 4];
affine();
// precompute table
Q.copy(this);
Q.dbl();
W[0] = new ECP();
W[0].copy(this);
for (i = 1; i < 8; i++)
{
W[i] = new ECP();
W[i].copy(W[i - 1]);
W[i].add(Q);
}
// convert the table to affine
if (ROM.CURVETYPE == ROM.WEIERSTRASS)
{
multiaffine(8, W);
}
// make exponent odd - add 2P if even, P if odd
t.copy(e);
s = t.parity();
t.inc(1);
t.norm();
ns = t.parity();
mt.copy(t);
mt.inc(1);
mt.norm();
t.cmove(mt, s);
Q.cmove(this, ns);
C.copy(Q);
nb = 1 + (t.nbits() + 3) / 4;
// convert exponent to signed 4-bit window
for (i = 0; i < nb; i++)
{
w[i] = (sbyte)(t.lastbits(5) - 16);
t.dec(w[i]);
t.norm();
t.fshr(4);
}
w[nb] = (sbyte)t.lastbits(5);
P.copy(W[(w[nb] - 1) / 2]);
for (i = nb - 1; i >= 0; i--)
{
Q.select(W, w[i]);
P.dbl();
P.dbl();
P.dbl();
P.dbl();
P.add(Q);
}
P.sub(C); // apply correction
}
P.affine();
return(P);
}
/* Return e.this+f.Q */
public ECP mul2(BIG e, ECP Q, BIG f)
{
BIG te = new BIG();
BIG tf = new BIG();
BIG mt = new BIG();
ECP S = new ECP();
ECP T = new ECP();
ECP C = new ECP();
ECP[] W = new ECP[8];
sbyte[] w = new sbyte[1 + (ROM.NLEN * ROM.BASEBITS + 1) / 2];
int i, s, ns, nb;
sbyte a, b;
affine();
Q.affine();
te.copy(e);
tf.copy(f);
// precompute table
W[1] = new ECP();
W[1].copy(this);
W[1].sub(Q);
W[2] = new ECP();
W[2].copy(this);
W[2].add(Q);
S.copy(Q);
S.dbl();
W[0] = new ECP();
W[0].copy(W[1]);
W[0].sub(S);
W[3] = new ECP();
W[3].copy(W[2]);
W[3].add(S);
T.copy(this);
T.dbl();
W[5] = new ECP();
W[5].copy(W[1]);
W[5].add(T);
W[6] = new ECP();
W[6].copy(W[2]);
W[6].add(T);
W[4] = new ECP();
W[4].copy(W[5]);
W[4].sub(S);
W[7] = new ECP();
W[7].copy(W[6]);
W[7].add(S);
// convert the table to affine
if (ROM.CURVETYPE == ROM.WEIERSTRASS)
{
multiaffine(8, W);
}
// if multiplier is odd, add 2, else add 1 to multiplier, and add 2P or P to correction
s = te.parity();
te.inc(1);
te.norm();
ns = te.parity();
mt.copy(te);
mt.inc(1);
mt.norm();
te.cmove(mt, s);
T.cmove(this, ns);
C.copy(T);
s = tf.parity();
tf.inc(1);
tf.norm();
ns = tf.parity();
mt.copy(tf);
mt.inc(1);
mt.norm();
tf.cmove(mt, s);
S.cmove(Q, ns);
C.add(S);
mt.copy(te);
mt.add(tf);
mt.norm();
nb = 1 + (mt.nbits() + 1) / 2;
// convert exponent to signed 2-bit window
for (i = 0; i < nb; i++)
{
a = (sbyte)(te.lastbits(3) - 4);
te.dec(a);
te.norm();
te.fshr(2);
b = (sbyte)(tf.lastbits(3) - 4);
tf.dec(b);
tf.norm();
tf.fshr(2);
w[i] = (sbyte)(4 * a + b);
}
w[nb] = (sbyte)(4 * te.lastbits(3) + tf.lastbits(3));
S.copy(W[(w[nb] - 1) / 2]);
for (i = nb - 1; i >= 0; i--)
{
T.select(W, w[i]);
S.dbl();
S.dbl();
S.add(T);
}
S.sub(C); // apply correction
S.affine();
return(S);
}
/* P*=e */
public ECP2 mul(BIG e)
{
/* fixed size windows */
int i, b, nb, m, s, ns;
BIG mt = new BIG();
BIG t = new BIG();
ECP2 P = new ECP2();
ECP2 Q = new ECP2();
ECP2 C = new ECP2();
ECP2[] W = new ECP2[8];
sbyte[] w = new sbyte[1 + (ROM.NLEN * ROM.BASEBITS + 3) / 4];
if (is_infinity())
{
return(new ECP2());
}
affine();
/* precompute table */
Q.copy(this);
Q.dbl();
W[0] = new ECP2();
W[0].copy(this);
for (i = 1; i < 8; i++)
{
W[i] = new ECP2();
W[i].copy(W[i - 1]);
W[i].add(Q);
}
/* convert the table to affine */
multiaffine(8, W);
/* make exponent odd - add 2P if even, P if odd */
t.copy(e);
s = t.parity();
t.inc(1);
t.norm();
ns = t.parity();
mt.copy(t);
mt.inc(1);
mt.norm();
t.cmove(mt, s);
Q.cmove(this, ns);
C.copy(Q);
nb = 1 + (t.nbits() + 3) / 4;
/* convert exponent to signed 4-bit window */
for (i = 0; i < nb; i++)
{
w[i] = (sbyte)(t.lastbits(5) - 16);
t.dec(w[i]);
t.norm();
t.fshr(4);
}
w[nb] = (sbyte)t.lastbits(5);
P.copy(W[(w[nb] - 1) / 2]);
for (i = nb - 1; i >= 0; i--)
{
Q.select(W, w[i]);
P.dbl();
P.dbl();
P.dbl();
P.dbl();
P.add(Q);
}
P.sub(C);
P.affine();
return(P);
}
/* r=ck^a.cl^n using XTR double exponentiation method on traces of FP12s. See Stam thesis. */
public FP4 xtr_pow2(FP4 ck, FP4 ckml, FP4 ckm2l, BIG a, BIG b)
{
a.norm();
b.norm();
BIG e = new BIG(a);
BIG d = new BIG(b);
BIG w = new BIG(0);
FP4 cu = new FP4(ck); // can probably be passed in w/o copying
FP4 cv = new FP4(this);
FP4 cumv = new FP4(ckml);
FP4 cum2v = new FP4(ckm2l);
FP4 r = new FP4(0);
FP4 t = new FP4(0);
int f2 = 0;
while (d.parity() == 0 && e.parity() == 0)
{
d.fshr(1);
e.fshr(1);
f2++;
}
while (BIG.comp(d, e) != 0)
{
if (BIG.comp(d, e) > 0)
{
w.copy(e);
w.imul(4);
w.norm();
if (BIG.comp(d, w) <= 0)
{
w.copy(d);
d.copy(e);
e.rsub(w);
e.norm();
t.copy(cv);
t.xtr_A(cu, cumv, cum2v);
cum2v.copy(cumv);
cum2v.conj();
cumv.copy(cv);
cv.copy(cu);
cu.copy(t);
}
else if (d.parity() == 0)
{
d.fshr(1);
r.copy(cum2v);
r.conj();
t.copy(cumv);
t.xtr_A(cu, cv, r);
cum2v.copy(cumv);
cum2v.xtr_D();
cumv.copy(t);
cu.xtr_D();
}
else if (e.parity() == 1)
{
d.sub(e);
d.norm();
d.fshr(1);
t.copy(cv);
t.xtr_A(cu, cumv, cum2v);
cu.xtr_D();
cum2v.copy(cv);
cum2v.xtr_D();
cum2v.conj();
cv.copy(t);
}
else
{
w.copy(d);
d.copy(e);
d.fshr(1);
e.copy(w);
t.copy(cumv);
t.xtr_D();
cumv.copy(cum2v);
cumv.conj();
cum2v.copy(t);
cum2v.conj();
t.copy(cv);
t.xtr_D();
cv.copy(cu);
cu.copy(t);
}
}
if (BIG.comp(d, e) < 0)
{
w.copy(d);
w.imul(4);
w.norm();
if (BIG.comp(e, w) <= 0)
{
e.sub(d);
e.norm();
t.copy(cv);
t.xtr_A(cu, cumv, cum2v);
cum2v.copy(cumv);
cumv.copy(cu);
cu.copy(t);
}
else if (e.parity() == 0)
{
w.copy(d);
d.copy(e);
d.fshr(1);
e.copy(w);
t.copy(cumv);
t.xtr_D();
cumv.copy(cum2v);
cumv.conj();
cum2v.copy(t);
cum2v.conj();
t.copy(cv);
t.xtr_D();
cv.copy(cu);
cu.copy(t);
}
else if (d.parity() == 1)
{
w.copy(e);
e.copy(d);
w.sub(d);
w.norm();
d.copy(w);
d.fshr(1);
t.copy(cv);
t.xtr_A(cu, cumv, cum2v);
cumv.conj();
cum2v.copy(cu);
cum2v.xtr_D();
cum2v.conj();
cu.copy(cv);
cu.xtr_D();
cv.copy(t);
}
else
{
d.fshr(1);
r.copy(cum2v);
r.conj();
t.copy(cumv);
t.xtr_A(cu, cv, r);
cum2v.copy(cumv);
cum2v.xtr_D();
cumv.copy(t);
cu.xtr_D();
}
}
}
r.copy(cv);
r.xtr_A(cu, cumv, cum2v);
for (int i = 0; i < f2; i++)
{
r.xtr_D();
}
r = r.xtr_pow(d);
return(r);
}
