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/**
* TfishYubikeyAuthenticator class file.
*
* @copyright Simon Wilkinson 2013-2017 (https://tuskfish.biz)
* @license https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html GNU General Public License (GPL) V2
* @author Simon Wilkinson <[email protected]>
* @version Release: 1.0
* @since 1.0
* @package security
*/
// Enable strict type declaration.
declare(strict_types=1);
if (!defined("TFISH_ROOT_PATH"))
die("TFISH_ERROR_ROOT_PATH_NOT_DEFINED");
/**
* Two-factor authentication class.
*
* Handles two-factor authentication via a Yubikey hardware token, available from yubico.com.
* Set up requires obtaining a Client ID and secret key from Yubico, please refer to the manual for
* instructions on how to set it up.
*
* Note that the Yubikey authentication methods within this class are Copyright Tom Corwine and
* distributed under the GPL (V2). Please see the separate copyright block within the class file.
*
* Do not attempt to use this file without reading the manual.
*
* @copyright Simon Wilkinson 2013-2017 (https://tuskfish.biz)
* @license https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html GNU General Public License (GPL) V2
* @author Simon Wilkinson <[email protected]>
* @version Release: 1.0
* @since 1.0
* @package security
*/
class TfishYubikeyAuthenticator
{
// Input.
/** @var int $_id ID of the Yubikey hardware token (first 12 characters of output). */
private $_id;
/** @var string $_signatureKey Yubikey API key obtained from
* https://upgrade.yubico.com/getapikey/ */
private $_signatureKey;
// Output.
/** @var string $_response Response message from last verification attempt */
private $_response;
// Internal.
/** @var array $_curlResult Response from cURL request to Yubico authentication server. */
private $_curlResult;
/** @var string $_curlError Error message. */
private $_curlError;
/** @var int $_timestampTolerance Timeout limit (expiry) for authentication requests. */
private $_timestampTolerance;
/** @var int $_curlTimeout Timeout limit when contacting Yubico authentication server. */
private $_curlTimeout;
/** Initialise default property values and unset unneeded ones. */
public function __construct()
{
if (defined("TFISH_YUBIKEY_ID")) {
$this->_id = (int) TFISH_YUBIKEY_ID;
}
if (defined("TFISH_YUBIKEY_SIGNATURE_KEY")) {
if (mb_strlen(TFISH_YUBIKEY_SIGNATURE_KEY, "UTF-8") === 28) {
$this->_signatureKey = base64_decode(TFISH_YUBIKEY_SIGNATURE_KEY);
}
} else {
trigger_error(TFISH_YUBIKEY_NO_SIGNATURE_KEY, E_USER_ERROR);
return false;
exit;
}
if (defined("TFISH_YUBIKEY_TIMESTAMP_TOLERANCE")) {
$this->_timestampTolerance = (int) TFISH_YUBIKEY_TIMESTAMP_TOLERANCE;
}
if (defined("TFISH_YUBIKEY_CURL_TIMEOUT")) {
$this->_curlTimeout = (int) TFISH_YUBIKEY_CURL_TIMEOUT;
}
}
/////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////
// Yubikey API methods, by Tom Corwine ([email protected])
//
// @license GNU General Public License (GPL) V2
//
// verify(string) - Accepts otp from Yubikey. Returns TRUE for authentication success,
// otherwise FALSE.
// getLastResponse() - Returns response message from verification attempt.
// getTimestampTolerance() - Gets the tolerance (+/-, in seconds) for timestamp
// verification
// setTimestampTolerance(int) - Sets the tolerance (in seconds, 0-86400) - default 600
// (10 minutes). Returns TRUE on success and FALSE on failure.
// getCurlTimeout() - Gets the timeout (in seconds) CURL uses before giving up on contacting
// Yubico's server.
// setCurlTimeout(int) - Sets the CURL timeout (in seconds, 0-600, 0 means indefinitely)
// - default 10.Returns TRUE on success and FALSE on failure.
//////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////
/**
* Returns the timestamp tolerance (seconds).
*
* Timestamp tolerance is how long an authentication request will be accepted after it is
* generated. You need to allow some time for discrepancies between clocks and user delays.
* Default: 10 minutes.
*
* @return int Timestamp tolerance (seconds).
*/
public function getTimestampTolerance()
{
return $this->_timestampTolerance;
}
/**
* Set the timestamp tolerance.
*
* @param int $int Timestamp tolerance (seconds).
* @return bool True on success, false on failure.
*/
public function setTimestampTolerance(int $int)
{
$int = (int) $int;
if ($int > 0 && $int < 86400) {
$this->_timestampTolerance = $int;
return true;
} else {
return false;
}
}
/**
* Get the timeout for cURL requests, in seconds.
*
* @return int cURL timeout (seconds).
*/
public function getCurlTimeout()
{
return $this->_curlTimeout;
}
/**
* Set the cURL timeout.
*
* @param int $int cURL timeout (seconds).
* @return bool True on success, false on failure.
*/
public function setCurlTimeout(int $int)
{
$int = (int) $int;
if ($int > 0 && $int < 600) {
$this->_curlTimeout = $int;
return true;
} else {
return false;
}
}
/**
* Returns response message from last verification attempt.
*
* @return string Last response message.
*/
public function getLastResponse()
{
return $this->_response;
}
/**
* Authenticate using a Yubikey one-time password.
*
* @param string $otp One time password generated by Yubikey hardware token.
* @return bool True for successful authentication, false if fail.
*/
public function verify(string $otp)
{
$otp = TfishFilter::trimString($otp);
unset($this->_response);
unset($this->_curlResult);
unset($this->_curlError);
$otp = mb_strtolower($otp, "UTF-8");
if (!$this->_id) {
$this->_response = "ID NOT SET";
return false;
}
if (!$this->otpIsProperLength($otp)) {
$this->_response = "BAD OTP LENGTH";
return false;
}
if (!$this->otpIsModhex($otp)) {
$this->_response = "OTP NOT MODHEX";
return false;
}
$urlParams = "id=" . $this->_id . "&otp=" . $otp;
$url = $this->createSignedRequest($urlParams);
// Returns 0 on success.
if ($this->curlRequest($url)) {
$this->_response = "ERROR CONNECTING TO YUBICO - " . $this->_curlError;
return false;
}
foreach ($this->_curlResult as $param) {
if (mb_substr($param, 0, 2, "UTF-8") === "h=")
$signature = substr(trim($param), 2);
if (mb_substr($param, 0, 2, "UTF-8") === "t=")
$timestamp = substr(trim($param), 2);
if (mb_substr($param, 0, 7, "UTF-8") === "status=")
$status = substr(trim($param), 7);
}
// Concatenate string for signature verification
$signedMessage = "status=" . $status . "&t=" . $timestamp;
if (!$this->resultSignatureIsGood($signedMessage, $signature)) {
$this->_response = "BAD RESPONSE SIGNATURE";
return false;
}
if (!$this->resultTimestampIsGood($timestamp)) {
$this->_response = "BAD TIMESTAMP";
return false;
}
if ($status != "OK") {
$this->_response = $status;
return false;
}
// Everything went well - We pass
$this->_response = "OK";
return true;
}
/**
* Create URL with embedded and signed authentication request for Yubico authentication server.
*
* @param string $urlParams URL parameters.
* @return string URL to Yubico authentication server with query string parameters attached.
*/
protected function createSignedRequest(string $urlParams)
{
$urlParams = TfishFilter::trimString($urlParams);
if ($this->_signatureKey) {
$hash = urlencode(base64_encode(hash_hmac("sha1", $urlParams, $this->_signatureKey,
true)));
return "https://api.yubico.com/wsapi/verify?" . $urlParams . "&h=" . $hash;
} else {
return "https://api.yubico.com/wsapi/verify?" . $urlParams;
}
}
/**
* Make cURL request.
*
* @param string $url Target URL.
* @return string Error message.
*/
protected function curlRequest(string $url)
{
$url = TfishFilter::trimString($url);
if (!TfishFilter::isUrl($url)) {
trigger_error(TFISH_ERROR_NOT_URL, E_USER_ERROR);
}
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_TIMEOUT, $this->_curlTimeout);
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, $this->_curlTimeout);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, false);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);
$this->_curlResult = explode("\n", curl_exec($ch));
$this->_curlError = curl_error($ch);
$error = curl_errno($ch);
curl_close($ch);
return $error;
}
/**
* Check Yubikey one time password is expected length.
*
* @param string $otp Yubikey one-time password.
* @return bool True if length is ok, otherwise false.
*/
protected function otpIsProperLength(string $otp)
{
$otp = TfishFilter::trimString($otp);
if (mb_strlen($otp, "UTF-8") === 44) {
return true;
} else {
return false;
}
}
/**
* Check Yubikey one time password is modhex encoded.
*
* @param string $otp Yubikey one-time password.
* @return bool True if modhex encoded, otherwise false.
*/
protected function otpIsModhex(string $otp)
{
$otp = TfishFilter::trimString($otp);
$modhexChars = array("c", "b", "d", "e", "f", "g", "h", "i", "j", "k", "l", "n", "r", "t",
"u", "v");
foreach (str_split($otp) as $char) {
if (!in_array($char, $modhexChars))
return false;
}
return true;
}
/**
* Check timestamp is within tolerance.
*
* @param string $timestamp Timestamp to check.
* @return bool True if timestamp is within tolerance, otherwise false.
*/
protected function resultTimestampIsGood(string $timestamp)
{
$timestamp = TfishFilter::trimString($timestamp);
// Turn times into 'seconds since Unix Epoch' for easy comparison
$now = date("U");
$timestampSeconds = (int) (date_format(date_create(mb_substr($timestamp, 0, -4, "UTF-8")), "U"));
// If date() functions above fail for any reason, so do we
if (!$timestamp || !$now)
return false;
if (($timestampSeconds + $this->_timestampTolerance) > $now &&
($timestampSeconds - $this->_timestampTolerance) < $now) {
return true;
} else {
return false;
}
}
/**
* Validate result signature.
*
* @param string $signedMessage Signed message.
* @param string $signature Signature.
* @return bool True if signature is good, otherwise false.
*/
protected function resultSignatureIsGood(string $signedMessage, string $signature)
{
$signedMessage = TfishFilter::trimString($signedMessage);
$signature = TfishFilter::trimString($signature);
if (!$this->_signatureKey)
return true;
if (base64_encode(hash_hmac("sha1", $signedMessage, $this->_signatureKey, true))
=== $signature) {
return true;
} else {
return false;
}
}
///////////////////////////////////////////////////////////////////////
///// END Yubikey API methods by Tom Corwine ([email protected]) /////
///////////////////////////////////////////////////////////////////////
}