1 files changed, 164 insertions, 0 deletions
diff --git a/JWT.php b/JWT.php
new file mode 100644
index 0000000..d1704e1
--- /dev/null
+++ b/JWT.php
@@ -0,0 +1,164 @@
+<?php
+
+/**
+ * JSON Web Token implementation
+ *
+ * Minimum implementation used by Realtime auth, based on this spec:
+ * http://self-issued.info/docs/draft-jones-json-web-token-01.html.
+ *
+ * @author Neuman Vong <neuman@twilio.com>
+ */
+class JWT
+{
+    /**
+     * @param string      $jwt    The JWT
+     * @param string|null $key    The secret key
+     * @param bool        $verify Don't skip verification process 
+     *
+     * @return object The JWT's payload as a PHP object
+     */
+    public static function decode($jwt, $key = null, $verify = true)
+    {
+        $tks = explode('.', $jwt);
+        if (count($tks) != 3) {
+            throw new UnexpectedValueException('Wrong number of segments');
+        }
+        list($headb64, $payloadb64, $cryptob64) = $tks;
+        if (null === ($header = JWT::jsonDecode(JWT::urlsafeB64Decode($headb64)))
+        ) {
+            throw new UnexpectedValueException('Invalid segment encoding');
+        }
+        if (null === $payload = JWT::jsonDecode(JWT::urlsafeB64Decode($payloadb64))
+        ) {
+            throw new UnexpectedValueException('Invalid segment encoding');
+        }
+        $sig = JWT::urlsafeB64Decode($cryptob64);
+        if ($verify) {
+            if (empty($header->alg)) {
+                throw new DomainException('Empty algorithm');
+            }
+            if ($sig != JWT::sign("$headb64.$payloadb64", $key, $header->alg)) {
+                throw new UnexpectedValueException('Signature verification failed');
+            }
+        }
+        return $payload;
+    }
+
+    /**
+     * @param object|array $payload PHP object or array
+     * @param string       $key     The secret key
+     * @param string       $algo    The signing algorithm
+     *
+     * @return string A JWT
+     */
+    public static function encode($payload, $key, $algo = 'HS256')
+    {
+        $header = array('typ' => 'jwt', 'alg' => $algo);
+
+        $segments = array();
+        $segments[] = JWT::urlsafeB64Encode(JWT::jsonEncode($header));
+        $segments[] = JWT::urlsafeB64Encode(JWT::jsonEncode($payload));
+        $signing_input = implode('.', $segments);
+
+        $signature = JWT::sign($signing_input, $key, $algo);
+        $segments[] = JWT::urlsafeB64Encode($signature);
+
+        return implode('.', $segments);
+    }
+
+    /**
+     * @param string $msg    The message to sign
+     * @param string $key    The secret key
+     * @param string $method The signing algorithm
+     *
+     * @return string An encrypted message
+     */
+    public static function sign($msg, $key, $method = 'HS256')
+    {
+        $methods = array(
+            'HS256' => 'sha256',
+            'HS384' => 'sha384',
+            'HS512' => 'sha512',
+        );
+        if (empty($methods[$method])) {
+            throw new DomainException('Algorithm not supported');
+        }
+        return hash_hmac($methods[$method], $msg, $key, true);
+    }
+
+    /**
+     * @param string $input JSON string
+     *
+     * @return object Object representation of JSON string
+     */
+    public static function jsonDecode($input)
+    {
+        $obj = json_decode($input);
+        if (function_exists('json_last_error') && $errno = json_last_error()) {
+            JWT::handleJsonError($errno);
+        }
+        else if ($obj === null && $input !== 'null') {
+            throw new DomainException('Null result with non-null input');
+        }
+        return $obj;
+    }
+
+    /**
+     * @param object|array $input A PHP object or array
+     *
+     * @return string JSON representation of the PHP object or array
+     */
+    public static function jsonEncode($input)
+    {
+        $json = json_encode($input);
+        if (function_exists('json_last_error') && $errno = json_last_error()) {
+            JWT::handleJsonError($errno);
+        }
+        else if ($json === 'null' && $input !== null) {
+            throw new DomainException('Null result with non-null input');
+        }
+        return $json;
+    }
+
+    /**
+     * @param string $input A base64 encoded string
+     *
+     * @return string A decoded string
+     */
+    public static function urlsafeB64Decode($input)
+    {
+        $padlen = 4 - strlen($input) % 4;
+        $input .= str_repeat('=', $padlen);
+        return base64_decode(strtr($input, '-_', '+/'));
+    }
+
+    /**
+     * @param string $input Anything really
+     *
+     * @return string The base64 encode of what you passed in
+     */
+    public static function urlsafeB64Encode($input)
+    {
+        return str_replace('=', '', strtr(base64_encode($input), '+/', '-_'));
+    }
+
+    /**
+     * @param int $errno An error number from json_last_error()
+     *
+     * @return void
+     */
+    private static function handleJsonError($errno)
+    {
+        $messages = array(
+            JSON_ERROR_DEPTH => 'Maximum stack depth exceeded',
+            JSON_ERROR_CTRL_CHAR => 'Unexpected control character found',
+            JSON_ERROR_SYNTAX => 'Syntax error, malformed JSON'
+        );
+        throw new DomainException(isset($messages[$errno])
+            ? $messages[$errno]
+            : 'Unknown JSON error: ' . $errno
+        );
+    }
+
+}
+