public CngKey GetOrGenerateKey(ECCurve?curve)
{
ThrowIfDisposed();
if (_lazyKey != null)
{
return(_lazyKey);
}
// We don't have a key yet so generate
Debug.Assert(curve.HasValue);
CngKeyCreationParameters creationParameters = new CngKeyCreationParameters()
{
ExportPolicy = CngExportPolicies.AllowPlaintextExport,
};
if (curve.Value.IsNamed)
{
creationParameters.Parameters.Add(CngKey.GetPropertyFromNamedCurve(curve.Value));
}
else if (curve.Value.IsPrime)
{
ECCurve eccurve = curve.Value;
byte[] parametersBlob = ECCng.GetPrimeCurveParameterBlob(ref eccurve);
CngProperty prop = new CngProperty(
Interop.BCrypt.BCryptPropertyStrings.BCRYPT_ECC_PARAMETERS,
parametersBlob,
CngPropertyOptions.None);
creationParameters.Parameters.Add(prop);
}
else
{
throw new PlatformNotSupportedException(SR.Format(SR.Cryptography_CurveNotSupported, curve.Value.CurveType.ToString()));
}
try
{
_lazyKey = CngKey.Create(DefaultKeyType ?? CngAlgorithm.ECDsa, null, creationParameters);
}
catch (CryptographicException e)
{
// Map to PlatformNotSupportedException if appropriate
ErrorCode errorCode = (ErrorCode)e.HResult;
if (curve.Value.IsNamed &&
errorCode == ErrorCode.NTE_INVALID_PARAMETER || errorCode == ErrorCode.NTE_NOT_SUPPORTED)
{
throw new PlatformNotSupportedException(SR.Format(SR.Cryptography_CurveNotSupported, curve.Value.Oid.FriendlyName), e);
}
throw;
}
return(_lazyKey);
}