//генерация публичного ключа (с помощью секретного).
public CECPoint publicKeyGen(BigInteger d)
{
CECPoint G = gDecompression();
CECPoint Q = CECPoint.multiply(G, d);
return(Q);
}
//формирование цифровой подписи.
public string DSGen(byte[] h, BigInteger d)
{
BigInteger a = new BigInteger(h);
BigInteger e = a % n;
if (e == 0)
{
e = 1;
}
BigInteger k = new BigInteger();
CECPoint C = new CECPoint();
BigInteger r = new BigInteger();
BigInteger s = new BigInteger();
do
{
do
{
k.genRandomBits(n.bitCount(), new Random());
}while ((k < 0) || (k > n));
C = CECPoint.multiply(G, k);
r = C.x % n;
s = ((r * d) + (k * e)) % n;
}while ((r == 0) || (s == 0));
string Rvector = padding(r.ToHexString(), n.bitCount() / 4);
string Svector = padding(s.ToHexString(), n.bitCount() / 4);
return(Rvector + Svector);
}
//проверка цифровой подписи.
public bool verifyDS(byte[] H, string sign, CECPoint Q)
{
string Rvector = sign.Substring(0, n.bitCount() / 4);
string Svector = sign.Substring(n.bitCount() / 4, n.bitCount() / 4);
BigInteger r = new BigInteger(Rvector, 16);
BigInteger s = new BigInteger(Svector, 16);
if ((r < 1) || (r > (n - 1)) || (s < 1) || (s > (n - 1)))
{
return(false);
}
BigInteger a = new BigInteger(H);
BigInteger e = a % n;
if (e == 0)
{
e = 1;
}
BigInteger v = e.modInverse(n);
BigInteger z1 = (s * v) % n;
BigInteger z2 = n + ((-(r * v)) % n);
this.G = gDecompression();
CECPoint A = CECPoint.multiply(G, z1);
CECPoint B = CECPoint.multiply(Q, z2);
CECPoint C = A + B;
BigInteger R = C.x % n;
if (R == r)
{
return(true);
}
else
{
return(false);
}
}