/// <summary>
/// Initializes a new instance of <see cref="EllipticCurveAlgorithm"/> class.
/// </summary>
/// <param name="oid">Object Identifier of the curve</param>
/// <param name="curveName">Curve name</param>
protected EllipticCurveAlgorithm(string oid, string curveName)
{
if (curveName == null)
{
throw new ArgumentNullException("curveName");
}
if (oid == null)
{
throw new ArgumentNullException("oid");
}
CurveName = curveName;
X9ECParameters x9 = CustomNamedCurves.GetByName(oid);
if (x9 != null)
{
_info = new ECKeyParametersExt(x9);
}
else
{
DerObjectIdentifier oidDer;
try
{
oidDer = new DerObjectIdentifier(oid);
}
catch (FormatException)
{
throw new InvalidOperationException("Unknown curve: '" + oid + "'.");
}
_info = new ECKeyParametersExt(oidDer);
}
BitLength = String.Equals(oid, "curve25519", StringComparison.OrdinalIgnoreCase)
? 256
: _info.Parameters.N.BitLength;
if (BitLength <= 256)
{
SignatureAlgorithm = "SHA-256withECDSA";
}
else if (BitLength <= 384)
{
SignatureAlgorithm = "SHA-384withECDSA";
}
else
{
SignatureAlgorithm = "SHA-512withECDSA";
}
}
private EllipticCurveAlgorithm(EllipticCurveAlgorithm obj)
{
_info = obj._info;
BitLength = obj.BitLength;
SignatureAlgorithm = obj.SignatureAlgorithm;
}