Demo.RSACryptoServiceProviderExtension.GetPrivateKeyDER C# (CSharp) Method

        internal static byte[] GetPrivateKeyDER(byte[] DERData)
        {
            byte[] data = null;
            UInt32 dwRSAPrivateKeyBlobSize = 0;
            IntPtr pRSAPrivateKeyBlob = IntPtr.Zero;
            if (RSACryptoServiceProviderExtension.CryptDecodeObject(CRYPT_ENCODING_FLAGS.X509_ASN_ENCODING | CRYPT_ENCODING_FLAGS.PKCS_7_ASN_ENCODING, new IntPtr((int)CRYPT_OUTPUT_TYPES.PKCS_RSA_PRIVATE_KEY),
                DERData, (UInt32)DERData.Length, CRYPT_DECODE_FLAGS.NONE, data, ref dwRSAPrivateKeyBlobSize))
            {
                data = new byte[dwRSAPrivateKeyBlobSize];
                if (!RSACryptoServiceProviderExtension.CryptDecodeObject(CRYPT_ENCODING_FLAGS.X509_ASN_ENCODING | CRYPT_ENCODING_FLAGS.PKCS_7_ASN_ENCODING, new IntPtr((int)CRYPT_OUTPUT_TYPES.PKCS_RSA_PRIVATE_KEY),
                    DERData, (UInt32)DERData.Length, CRYPT_DECODE_FLAGS.NONE, data, ref dwRSAPrivateKeyBlobSize))
                    throw new Win32Exception(Marshal.GetLastWin32Error());
            }
            else
                throw new Win32Exception(Marshal.GetLastWin32Error());
            return data;
        }

 /// <summary>Extension method which initializes an RSACryptoServiceProvider from a DER private key blob.</summary>
 public static void LoadPrivateKeyDER(this RSACryptoServiceProvider provider, byte[] DERData)
 {
     byte[] privateKeyBlob = RSACryptoServiceProviderExtension.GetPrivateKeyDER(DERData);
     provider.ImportCspBlob(privateKeyBlob);
 }