Opc.Ua.DirectoryCertificateStore.LoadPrivateKey C# (CSharp) Method

        public X509Certificate2 LoadPrivateKey(string thumbprint, string subjectName, string password)
        {
            if (m_certificateSubdir == null || !m_certificateSubdir.Exists)
            {
                return null;
            }

            if (string.IsNullOrEmpty(thumbprint) && string.IsNullOrEmpty(subjectName))
            {
                return null;
            }

            foreach (FileInfo file in m_certificateSubdir.GetFiles("*.der"))
            {
                try
                {
                    X509Certificate2 certificate = new X509Certificate2(file.FullName);

                    if (!String.IsNullOrEmpty(thumbprint))
                    {
                        if (!string.Equals(certificate.Thumbprint, thumbprint, StringComparison.CurrentCultureIgnoreCase))
                        {
                            continue;
                        }
                    }

                    if (!String.IsNullOrEmpty(subjectName))
                    {
                        if (!Utils.CompareDistinguishedName(subjectName, certificate.Subject))
                        {
                            if (subjectName.Contains("=") || !certificate.Subject.Contains("CN=" + subjectName))
                            {
                                continue;
                            }
                        }
                    }

                    string fileRoot = file.Name.Substring(0, file.Name.Length - file.Extension.Length);

                    StringBuilder filePath = new StringBuilder();
                    filePath.Append(m_privateKeySubdir.FullName);
                    filePath.Append(Path.DirectorySeparatorChar);
                    filePath.Append(fileRoot);

                    FileInfo privateKeyFile = new FileInfo(filePath.ToString() + ".pfx");
                    RSA rsa = null;

                    try
                    {
                        certificate = new X509Certificate2(
                            privateKeyFile.FullName,
                            (password == null) ? String.Empty : password,
                            X509KeyStorageFlags.Exportable | X509KeyStorageFlags.MachineKeySet);
                        rsa = certificate.GetRSAPrivateKey();
                    }
                    catch (Exception)
                    {
                        certificate = new X509Certificate2(
                            privateKeyFile.FullName,
                            (password == null) ? String.Empty : password,
                            X509KeyStorageFlags.Exportable | X509KeyStorageFlags.DefaultKeySet);
                        rsa = certificate.GetRSAPrivateKey();
                    }
                    if (rsa != null)
                    {
                        int inputBlockSize = rsa.KeySize / 8 - 42;
                        byte[] bytes1 = rsa.Encrypt(new byte[inputBlockSize], RSAEncryptionPadding.OaepSHA1);
                        byte[] bytes2 = rsa.Decrypt(bytes1, RSAEncryptionPadding.OaepSHA1);
                        if (bytes2 != null)
                        {
                            // Utils.Trace(1, "RSA: {0}", certificate.Thumbprint);
                            return certificate;
                        }
                    }
                }
                catch (Exception e)
                {
                    Utils.Trace(e, "Could not load private key for certificate " + subjectName);
                }
            }

            return null;
        }

        /// <summary>
        /// Loads the private key for the certificate with an optional password.
        /// </summary>
        public async Task <X509Certificate2> LoadPrivateKey(String password)
        {
            if (this.StoreType == CertificateStoreType.Directory)
            {
                using (DirectoryCertificateStore store = new DirectoryCertificateStore())
                {
                    store.Open(this.StorePath);
                    m_certificate = store.LoadPrivateKey(this.Thumbprint, this.SubjectName, password);
                    return(m_certificate);
                }
            }

            return(await Find(true));
        }