/**
   * Creates a String representation of the given object.
   *
   * @param certificate to print
   * @return the String representation
   */
  private String toString(Object certificate) {
    final StringBuilder sb = new StringBuilder();
    sb.append("<html><body>\n");

    if (certificate instanceof X509Certificate) {
      renderX509(sb, (X509Certificate) certificate);
    } else {
      sb.append("<pre>\n");
      sb.append(certificate.toString());
      sb.append("</pre>\n");
    }

    sb.append("</body></html>");
    return sb.toString();
  }
 /**
  * Add a field.
  *
  * @param sb StringBuilder to append to
  * @param field name of the certificate field
  * @param value to print
  */
 private void addField(StringBuilder sb, String field, String value) {
   sb.append("<tr>")
       .append("<td style='margin-left: 5pt; margin-right: 25pt;")
       .append(" white-space: nowrap'>")
       .append(field)
       .append("</td>")
       .append("<td>")
       .append(value)
       .append("</td>")
       .append("</tr>\n");
 }
 /**
  * Add a title.
  *
  * @param sb StringBuilder to append to
  * @param title to print
  */
 private void addTitle(StringBuilder sb, String title) {
   sb.append("<tr><td colspan='2'")
       .append(" style='margin-top: 5pt; white-space: nowrap'><p><b>")
       .append(title)
       .append("</b></p></td></tr>\n");
 }
  /**
   * Appends an HTML representation of the given X509Certificate.
   *
   * @param sb StringBuilder to append to
   * @param certificate to print
   */
  private void renderX509(StringBuilder sb, X509Certificate certificate) {
    X500Principal issuer = certificate.getIssuerX500Principal();
    X500Principal subject = certificate.getSubjectX500Principal();

    sb.append("<table cellspacing='1' cellpadding='1'>\n");

    // subject
    addTitle(sb, R.getI18NString("service.gui.CERT_INFO_ISSUED_TO"));
    try {
      for (Rdn name : new LdapName(subject.getName()).getRdns()) {
        String nameType = name.getType();
        String lblKey = "service.gui.CERT_INFO_" + nameType;
        String lbl = R.getI18NString(lblKey);

        if ((lbl == null) || ("!" + lblKey + "!").equals(lbl)) lbl = nameType;

        final String value;
        Object nameValue = name.getValue();

        if (nameValue instanceof byte[]) {
          byte[] nameValueAsByteArray = (byte[]) nameValue;

          value = getHex(nameValueAsByteArray) + " (" + new String(nameValueAsByteArray) + ")";
        } else value = nameValue.toString();

        addField(sb, lbl, value);
      }
    } catch (InvalidNameException ine) {
      addField(sb, R.getI18NString("service.gui.CERT_INFO_CN"), subject.getName());
    }

    // issuer
    addTitle(sb, R.getI18NString("service.gui.CERT_INFO_ISSUED_BY"));
    try {
      for (Rdn name : new LdapName(issuer.getName()).getRdns()) {
        String nameType = name.getType();
        String lblKey = "service.gui.CERT_INFO_" + nameType;
        String lbl = R.getI18NString(lblKey);

        if ((lbl == null) || ("!" + lblKey + "!").equals(lbl)) lbl = nameType;

        final String value;
        Object nameValue = name.getValue();

        if (nameValue instanceof byte[]) {
          byte[] nameValueAsByteArray = (byte[]) nameValue;

          value = getHex(nameValueAsByteArray) + " (" + new String(nameValueAsByteArray) + ")";
        } else value = nameValue.toString();

        addField(sb, lbl, value);
      }
    } catch (InvalidNameException ine) {
      addField(sb, R.getI18NString("service.gui.CERT_INFO_CN"), issuer.getName());
    }

    // validity
    addTitle(sb, R.getI18NString("service.gui.CERT_INFO_VALIDITY"));
    addField(
        sb,
        R.getI18NString("service.gui.CERT_INFO_ISSUED_ON"),
        certificate.getNotBefore().toString());
    addField(
        sb,
        R.getI18NString("service.gui.CERT_INFO_EXPIRES_ON"),
        certificate.getNotAfter().toString());

    addTitle(sb, R.getI18NString("service.gui.CERT_INFO_FINGERPRINTS"));
    try {
      String sha1String = getThumbprint(certificate, "SHA1");
      String md5String = getThumbprint(certificate, "MD5");

      addField(sb, "SHA1:", sha1String);
      addField(sb, "MD5:", md5String);
    } catch (CertificateException e) {
      // do nothing as we cannot show this value
    }

    addTitle(sb, R.getI18NString("service.gui.CERT_INFO_CERT_DETAILS"));

    addField(
        sb,
        R.getI18NString("service.gui.CERT_INFO_SER_NUM"),
        certificate.getSerialNumber().toString());

    addField(
        sb, R.getI18NString("service.gui.CERT_INFO_VER"), String.valueOf(certificate.getVersion()));

    addField(
        sb,
        R.getI18NString("service.gui.CERT_INFO_SIGN_ALG"),
        String.valueOf(certificate.getSigAlgName()));

    addTitle(sb, R.getI18NString("service.gui.CERT_INFO_PUB_KEY_INFO"));

    addField(
        sb,
        R.getI18NString("service.gui.CERT_INFO_ALG"),
        certificate.getPublicKey().getAlgorithm());

    if (certificate.getPublicKey().getAlgorithm().equals("RSA")) {
      RSAPublicKey key = (RSAPublicKey) certificate.getPublicKey();

      addField(
          sb,
          R.getI18NString("service.gui.CERT_INFO_PUB_KEY"),
          R.getI18NString(
              "service.gui.CERT_INFO_KEY_BYTES_PRINT",
              new String[] {
                String.valueOf(key.getModulus().toByteArray().length - 1),
                key.getModulus().toString(16)
              }));

      addField(
          sb, R.getI18NString("service.gui.CERT_INFO_EXP"), key.getPublicExponent().toString());

      addField(
          sb,
          R.getI18NString("service.gui.CERT_INFO_KEY_SIZE"),
          R.getI18NString(
              "service.gui.CERT_INFO_KEY_BITS_PRINT",
              new String[] {String.valueOf(key.getModulus().bitLength())}));
    } else if (certificate.getPublicKey().getAlgorithm().equals("DSA")) {
      DSAPublicKey key = (DSAPublicKey) certificate.getPublicKey();

      addField(sb, "Y:", key.getY().toString(16));
    }

    addField(
        sb,
        R.getI18NString("service.gui.CERT_INFO_SIGN"),
        R.getI18NString(
            "service.gui.CERT_INFO_KEY_BYTES_PRINT",
            new String[] {
              String.valueOf(certificate.getSignature().length), getHex(certificate.getSignature())
            }));

    sb.append("</table>\n");
  }