/* 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);
}
/* these next two functions implement elligator squared - http://eprint.iacr.org/2014/043 */
/* Elliptic curve point E in format (0x04,x,y} is converted to form {0x0-,u,v} */
/* Note that u and v are indistinguisible from random strings */
public static int ENCODING(RAND rng, sbyte[] E)
{
int rn, m, su, sv;
sbyte[] T = new sbyte[EFS];
for (int i = 0; i < EFS; i++)
{
T[i] = E[i + 1];
}
BIG u = BIG.fromBytes(T);
for (int i = 0; i < EFS; i++)
{
T[i] = E[i + EFS + 1];
}
BIG v = BIG.fromBytes(T);
ECP P = new ECP(u, v);
if (P.is_infinity())
{
return(INVALID_POINT);
}
BIG p = new BIG(ROM.Modulus);
u = BIG.randomnum(p, rng);
su = rng.Byte; //if (su<0) su=-su;
su %= 2;
ECP W = map(u, su);
P.sub(W);
sv = P.S;
rn = unmap(v, P);
m = rng.Byte; //if (m<0) m=-m;
m %= rn;
v.inc(m + 1);
E[0] = (sbyte)(su + 2 * sv);
u.toBytes(T);
for (int i = 0; i < EFS; i++)
{
E[i + 1] = T[i];
}
v.toBytes(T);
for (int i = 0; i < EFS; i++)
{
E[i + EFS + 1] = T[i];
}
return(0);
}
/* validate public key. Set full=true for fuller check */
public static int PUBLIC_KEY_VALIDATE(bool full, sbyte[] W)
{
BIG r;
ECP WP = ECP.fromBytes(W);
int res = 0;
r = new BIG(ROM.CURVE_Order);
if (WP.is_infinity())
{
res = INVALID_PUBLIC_KEY;
}
if (res == 0 && full)
{
WP = WP.mul(r);
if (!WP.is_infinity())
{
res = INVALID_PUBLIC_KEY;
}
}
return(res);
}
/* R=R1+R2 in group G1 */
public static int RECOMBINE_G1(sbyte[] R1, sbyte[] R2, sbyte[] R)
{
ECP P = ECP.fromBytes(R1);
ECP Q = ECP.fromBytes(R2);
if (P.is_infinity() || Q.is_infinity())
{
return(INVALID_POINT);
}
P.add(Q);
P.toBytes(R);
return(0);
}
/* these next two functions help to implement elligator squared - http://eprint.iacr.org/2014/043 */
/* maps a random u to a point on the curve */
public static ECP map(BIG u, int cb)
{
ECP P;
BIG x = new BIG(u);
BIG p = new BIG(ROM.Modulus);
x.mod(p);
while (true)
{
P = new ECP(x, cb);
if (!P.is_infinity())
{
break;
}
x.inc(1);
x.norm();
}
return(P);
}
public static ECP mapit(sbyte[] h)
{
BIG q = new BIG(ROM.Modulus);
BIG x = BIG.fromBytes(h);
x.mod(q);
ECP P;
while (true)
{
P = new ECP(x, 0);
if (!P.is_infinity())
{
break;
}
x.inc(1);
x.norm();
}
return(P);
}
/* Implement step 2 on client side of MPin protocol */
public static int CLIENT_2(sbyte[] X, sbyte[] Y, sbyte[] SEC)
{
BIG r = new BIG(ROM.CURVE_Order);
ECP P = ECP.fromBytes(SEC);
if (P.is_infinity())
{
return(INVALID_POINT);
}
BIG px = BIG.fromBytes(X);
BIG py = BIG.fromBytes(Y);
px.add(py);
px.mod(r);
px.rsub(r);
PAIR.G1mul(P, px).toBytes(SEC);
return(0);
}
/* Extract PIN from TOKEN for identity CID */
public static int EXTRACT_PIN(sbyte[] CID, int pin, sbyte[] TOKEN)
{
ECP P = ECP.fromBytes(TOKEN);
if (P.is_infinity())
{
return(INVALID_POINT);
}
sbyte[] h = hashit(0, CID);
ECP R = mapit(h);
pin %= MAXPIN;
R = R.pinmul(pin, PBLEN);
P.sub(R);
P.toBytes(TOKEN);
return(0);
}
/* returns u derived from P. Random value in range 1 to return value should then be added to u */
public static int unmap(BIG u, ECP P)
{
int s = P.S;
ECP R;
int r = 0;
BIG x = P.X;
u.copy(x);
while (true)
{
u.dec(1);
u.norm();
r++;
R = new ECP(u, s);
if (!R.is_infinity())
{
break;
}
}
return(r);
}
/* Test P == Q */
public bool Equals(ECP Q)
{
if (is_infinity() && Q.is_infinity())
{
return(true);
}
if (is_infinity() || Q.is_infinity())
{
return(false);
}
if (ROM.CURVETYPE == ROM.WEIERSTRASS)
{
FP zs2 = new FP(z);
zs2.sqr();
FP zo2 = new FP(Q.z);
zo2.sqr();
FP zs3 = new FP(zs2);
zs3.mul(z);
FP zo3 = new FP(zo2);
zo3.mul(Q.z);
zs2.mul(Q.x);
zo2.mul(x);
if (!zs2.Equals(zo2))
{
return(false);
}
zs3.mul(Q.y);
zo3.mul(y);
if (!zs3.Equals(zo3))
{
return(false);
}
}
else
{
FP a = new FP(0);
FP b = new FP(0);
a.copy(x);
a.mul(Q.z);
a.reduce();
b.copy(Q.x);
b.mul(z);
b.reduce();
if (!a.Equals(b))
{
return(false);
}
if (ROM.CURVETYPE == ROM.EDWARDS)
{
a.copy(y);
a.mul(Q.z);
a.reduce();
b.copy(Q.y);
b.mul(z);
b.reduce();
if (!a.Equals(b))
{
return(false);
}
}
}
return(true);
}
/* calculate common key on server side */
/* Z=r.A - no time permits involved */
public static int SERVER_KEY(sbyte[] Z, sbyte[] SST, sbyte[] W, sbyte[] xID, sbyte[] xCID, sbyte[] SK)
{
HASH H = new HASH();
sbyte[] t = new sbyte[EFS];
ECP2 sQ = ECP2.fromBytes(SST);
if (sQ.is_infinity())
{
return(INVALID_POINT);
}
ECP R = ECP.fromBytes(Z);
if (R.is_infinity())
{
return(INVALID_POINT);
}
ECP U;
if (xCID != null)
{
U = ECP.fromBytes(xCID);
}
else
{
U = ECP.fromBytes(xID);
}
if (U.is_infinity())
{
return(INVALID_POINT);
}
BIG w = BIG.fromBytes(W);
U = PAIR.G1mul(U, w);
FP12 g = PAIR.ate(sQ, R);
g = PAIR.fexp(g);
FP4 c = g.trace();
c.geta().A.toBytes(t);
H.process_array(t);
c.geta().B.toBytes(t);
H.process_array(t);
c.getb().A.toBytes(t);
H.process_array(t);
c.getb().B.toBytes(t);
H.process_array(t);
U.X.toBytes(t);
H.process_array(t);
U.Y.toBytes(t);
H.process_array(t);
t = H.hash();
for (int i = 0; i < PAS; i++)
{
SK[i] = t[i];
}
return(0);
}
/* calculate common key on client side */
/* wCID = w.(A+AT) */
public static int CLIENT_KEY(sbyte[] G1, sbyte[] G2, int pin, sbyte[] R, sbyte[] X, sbyte[] wCID, sbyte[] CK)
{
HASH H = new HASH();
sbyte[] t = new sbyte[EFS];
FP12 g1 = FP12.fromBytes(G1);
FP12 g2 = FP12.fromBytes(G2);
BIG z = BIG.fromBytes(R);
BIG x = BIG.fromBytes(X);
ECP W = ECP.fromBytes(wCID);
if (W.is_infinity())
{
return(INVALID_POINT);
}
W = PAIR.G1mul(W, x);
FP2 f = new FP2(new BIG(ROM.CURVE_Fra), new BIG(ROM.CURVE_Frb));
BIG r = new BIG(ROM.CURVE_Order);
BIG q = new BIG(ROM.Modulus);
BIG m = new BIG(q);
m.mod(r);
BIG a = new BIG(z);
a.mod(m);
BIG b = new BIG(z);
b.div(m);
g2.pinpow(pin, PBLEN);
g1.mul(g2);
FP4 c = g1.trace();
g2.copy(g1);
g2.frob(f);
FP4 cp = g2.trace();
g1.conj();
g2.mul(g1);
FP4 cpm1 = g2.trace();
g2.mul(g1);
FP4 cpm2 = g2.trace();
c = c.xtr_pow2(cp, cpm1, cpm2, a, b);
c.geta().A.toBytes(t);
H.process_array(t);
c.geta().B.toBytes(t);
H.process_array(t);
c.getb().A.toBytes(t);
H.process_array(t);
c.getb().B.toBytes(t);
H.process_array(t);
W.X.toBytes(t);
H.process_array(t);
W.Y.toBytes(t);
H.process_array(t);
t = H.hash();
for (int i = 0; i < PAS; i++)
{
CK[i] = t[i];
}
return(0);
}
