+if ( ! function_exists('hash_hmac') ):
+function hash_hmac($algo, $data, $key, $raw_output = false) {
+ $packs = array('md5' => 'H32', 'sha1' => 'H40');
+
+ if ( !isset($packs[$algo]) )
+ return false;
+
+ $pack = $packs[$algo];
+
+ if (strlen($key) > 64)
+ $key = pack($pack, $algo($key));
+ else if (strlen($key) < 64)
+ $key = str_pad($key, 64, chr(0));
+
+ $ipad = (substr($key, 0, 64) ^ str_repeat(chr(0x36), 64));
+ $opad = (substr($key, 0, 64) ^ str_repeat(chr(0x5C), 64));
+
+ return $algo($opad . pack($pack, $algo($ipad . $data)));
+}
+endif;
+
+if ( ! function_exists('mb_strcut') ):
+ function mb_strcut( $str, $start, $length=null, $encoding=null ) {
+ return _mb_strcut($str, $start, $length, $encoding);
+ }
+endif;
+
+function _mb_strcut( $str, $start, $length=null, $encoding=null ) {
+ // the solution below, works only for utf-8, so in case of a different
+ // charset, just use built-in substr
+ $charset = get_option( 'blog_charset' );
+ if ( !in_array( $charset, array('utf8', 'utf-8', 'UTF8', 'UTF-8') ) ) {
+ return is_null( $length )? substr( $str, $start ) : substr( $str, $start, $length);
+ }
+ // use the regex unicode support to separate the UTF-8 characters into an array
+ preg_match_all( '/./us', $str, $match );
+ $chars = is_null( $length )? array_slice( $match[0], $start ) : array_slice( $match[0], $start, $length );
+ return implode( '', $chars );
+}
+