/* convert from byte array to point */
public static ECP fromBytes(sbyte[] b)
{
sbyte[] t = new sbyte[ROM.MODBYTES];
BIG p = new BIG(ROM.Modulus);
for (int i = 0; i < ROM.MODBYTES; i++)
{
t[i] = b[i + 1];
}
BIG px = BIG.fromBytes(t);
if (BIG.comp(px, p) >= 0)
{
return(new ECP());
}
if (b[0] == 0x04)
{
for (int i = 0; i < ROM.MODBYTES; i++)
{
t[i] = b[i + ROM.MODBYTES + 1];
}
BIG py = BIG.fromBytes(t);
if (BIG.comp(py, p) >= 0)
{
return(new ECP());
}
return(new ECP(px, py));
}
else
{
return(new ECP(px));
}
}
/* IEEE1363 ECDSA Signature Verification. Signature C and D on F is verified using public key W */
public static int ECPVP_DSA(sbyte[] W, sbyte[] F, sbyte[] C, sbyte[] D)
{
BIG r, gx, gy, f, c, d, h2;
int res = 0;
ECP G, WP, P;
HASH H = new HASH();
H.process_array(F);
sbyte[] B = H.hash();
gx = new BIG(ROM.CURVE_Gx);
gy = new BIG(ROM.CURVE_Gy);
G = new ECP(gx, gy);
r = new BIG(ROM.CURVE_Order);
c = BIG.fromBytes(C);
d = BIG.fromBytes(D);
f = BIG.fromBytes(B);
if (c.iszilch() || BIG.comp(c, r) >= 0 || d.iszilch() || BIG.comp(d, r) >= 0)
{
res = INVALID;
}
if (res == 0)
{
d.invmodp(r);
f.copy(BIG.modmul(f, d, r));
h2 = BIG.modmul(c, d, r);
WP = ECP.fromBytes(W);
if (WP.is_infinity())
{
res = ERROR;
}
else
{
P = new ECP();
P.copy(WP);
P = P.mul2(h2, G, f);
if (P.is_infinity())
{
res = INVALID;
}
else
{
d = P.X;
d.mod(r);
if (BIG.comp(d, c) != 0)
{
res = INVALID;
}
}
}
}
return(res);
}
/* return TRUE if this==a */
public bool Equals(FP a)
{
a.reduce();
reduce();
if (BIG.comp(a.x, x) == 0)
{
return(true);
}
return(false);
}
/* compare x and y - must be normalised, and of same length */
public static int comp(FF a, FF b)
{
int i, j;
for (i = a.length - 1; i >= 0; i--)
{
j = BIG.comp(a.v[i], b.v[i]);
if (j != 0)
{
return(j);
}
}
return(0);
}
/* 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);
}
