public bool Verify_Signature(byte[] message, byte[] signature, ec_point Q)
{
byte[] byte_r = new byte[hash_length / 8];
byte[] byte_s = new byte[hash_length / 8];
Array.Copy(signature, 0, byte_r, 0, hash_length / 8);
Array.Copy(signature, hash_length / 8, byte_s, 0, hash_length / 8);
BigInteger r = new BigInteger(byte_r);
BigInteger s = new BigInteger(byte_s);
if (r < 1 || r > q - 1 || s < 1 || s > q - 1)
{
return(false);
}
byte[] hash = stribog.Hash(message);
BigInteger alpha = new BigInteger(hash);
BigInteger e = math.mod(alpha, q) == 0 ? math.mod(alpha, q) : 1;
//проверка из примера госта
e = BigInteger.Parse("20798893674476452017134061561508270130637142515379653289952617252661468872421");
BigInteger v = math.Ext_Euclidian(e, q);
BigInteger z1 = math.mod(s * v, q);
BigInteger z2 = math.mod(-(r * v), q);
ec_point C = z1 * point + z2 * Q;
BigInteger R = math.mod(C.X, q);
if (R == r)
{
return(true);
}
return(false);
}
public signature(ec_point point, BigInteger q)
{
this.point = point;
this.q = q;
if (q > BigInteger.Pow(2, 254) && q < BigInteger.Pow(2, 256))
{
hash_length = 256;
}
else
if (q > BigInteger.Pow(2, 508) && q < BigInteger.Pow(2, 512))
{
hash_length = 512;
}
else
{
throw new Exception("wrong q value");
}
stribog = new stribog(hash_length);
}
public static ec_point operator *(ec_point point, BigInteger k)
{
ec_point result = point;
k -= 1;
while (k > 0)
{
if (k % 2 != 0)
{
result = result + point;
--k;
}
else
{
k = k / 2;
point = point + point;
}
}
return(result);
}
public byte[] Generate_Signature(byte[] message, BigInteger d)
{
byte[] hash = stribog.Hash(message);
BigInteger alpha = new BigInteger(hash);
BigInteger e = math.mod(alpha, q) == 0 ? math.mod(alpha, q) : 1;
//проверка из примера госта
e = BigInteger.Parse("20798893674476452017134061561508270130637142515379653289952617252661468872421");
BigInteger k;
BigInteger r;
BigInteger S;
do
{
do
{
do
{
k = Random_BigInt(hash_length / 8);
}while (k < 1 || k > q);
//проверка из госта
k = BigInteger.Parse("53854137677348463731403841147996619241504003434302020712960838528893196233395");
ec_point C = point * k;
r = math.mod(C.X, q);
}while (r == 0);
S = math.mod(r * d + k * e, q);
}while (S == 0);
byte[] signature = new byte[hash_length / 4];
Array.Copy(r.ToByteArray(), 0, signature, 0, hash_length / 8);
Array.Copy(S.ToByteArray(), 0, signature, hash_length / 8, hash_length / 8);
return(signature);
}