/* Calculate a public/private EC GF(p) key pair W,S where W=S.G mod EC(p),
* where S is the secret key and W is the public key
* and G is fixed generator.
* If RNG is NULL then the private key is provided externally in S
* otherwise it is generated randomly internally */
public static int KEY_PAIR_GENERATE(RAND RNG, sbyte[] S, sbyte[] W)
{
BIG r, gx, gy, s;
ECP G, WP;
int res = 0;
sbyte[] T = new sbyte[EFS];
gx = new BIG(ROM.CURVE_Gx);
if (ROM.CURVETYPE != ROM.MONTGOMERY)
{
gy = new BIG(ROM.CURVE_Gy);
G = new ECP(gx, gy);
}
else
{
G = new ECP(gx);
}
r = new BIG(ROM.CURVE_Order);
if (RNG == null)
{
s = BIG.fromBytes(S);
}
else
{
s = BIG.randomnum(r, RNG);
s.toBytes(T);
for (int i = 0; i < EGS; i++)
{
S[i] = T[i];
}
}
WP = G.mul(s);
WP.toBytes(W);
return(res);
}
