/// <summary>
/// Returns the private key.
/// </summary>
/// <returns></returns>
public byte[] GetPrivateKey()
{
EnsurePrivate();
var publicKey = new DerBitString(PublicKey.Q.GetEncoded());
var ecpk = new ECPrivateKeyStructure(BitLength, PrivateKey.D, publicKey, PublicKey.PublicKeyParamSet);
return(ecpk.GetDerEncoded());
}