Exemplo n.º 1
0
        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);
        }