secretSalt = $secretSalt; $this->lifetime = $lifetime; $this->skew = $skew; } public function addVerificationData($data) { $this->secretSalt .= '|' . $data; } /** * Calculate the current time offset to the current time slot. * With some amount of time skew */ private function get_offset() { return ( (time() - $this->skew) % ($this->lifetime + $this->skew) ); } /** * Calculate the given time slot for a given offset. */ private function calculate_time_slot($offset) { #echo 'lifetime is: ' . $this->lifetime; $timeslot = floor( (time() - $offset) / ($this->lifetime + $this->skew) ); return $timeslot; } /** * Calculates a token value for a given offset */ private function calculate_tokenvalue($offset) { // A secret salt that should be randomly generated for each installation. #echo 'Secret salt is: ' . $this->secretSalt; #echo '

Calculating sha1( ' . $this->calculate_time_slot($offset) . ':' . $this->secretSalt . ' )
'; return sha1( $this->calculate_time_slot($offset) . ':' . $this->secretSalt); } /** * Generates a token which contains of a offset and a token value. Using current offset */ public function generate_token() { $current_offset = $this->get_offset(); return dechex($current_offset) . '-' . $this->calculate_tokenvalue($current_offset); } /** * Validates a full token, by calculating the token value for the provided * offset and compares. */ public function validate_token($token) { $splittedtoken = explode('-', $token); $offset = hexdec($splittedtoken[0]); $value = $splittedtoken[1]; #echo 'compare [' . $this->calculate_tokenvalue($offset). '] with [' . $value . '] offset was [' . $offset. ']'; return ($this->calculate_tokenvalue($offset) === $value); } }