note 88023 added to function.uniqid

This builds slightly on david's post below. The differences are that it doesn't require Cake anymore and there is a graceful fallback for /dev/urandom in case that isn't available (/dev/urandom is not available on windows systems for example). Since it uses mt_rand(), it is still cryptographically secure. <?php /** * @brief Generates a Universally Unique IDentifier, version 4. * * This function generates a truly random UUID. The built in CakePHP String::uuid() function * is not cryptographically secure. You should uses this function instead. * * @see http://tools.ietf.org/html/rfc4122#section-4.4 * @see http://en.wikipedia.org/wiki/UUID * @return string A UUID, made up of 32 hex digits and 4 hyphens. */ function uuidSecure() { $pr_bits = null; $fp = @fopen('/dev/urandom','rb'); if ($fp !== false) { $pr_bits .= @fread($fp, 16); @fclose($fp); } else { // If /dev/urandom isn't available (eg: in non-unix systems), use mt_rand(). $pr_bits = ""; for($cnt=0; $cnt < 16; $cnt++){ $pr_bits .= chr(mt_rand(0, 255)); } } $time_low = bin2hex(substr($pr_bits,0, 4)); $time_mid = bin2hex(substr($pr_bits,4, 2)); $time_hi_and_version = bin2hex(substr($pr_bits,6, 2)); $clock_seq_hi_and_reserved = bin2hex(substr($pr_bits,8, 2)); $node = bin2hex(substr($pr_bits,10, 6)); /** * Set the four most significant bits (bits 12 through 15) of the * time_hi_and_version field to the 4-bit version number from * Section 4.1.3. * @see http://tools.ietf.org/html/rfc4122#section-4.1.3 */ $time_hi_and_version = hexdec($time_hi_and_version); $time_hi_and_version = $time_hi_and_version >> 4; $time_hi_and_version = $time_hi_and_version | 0x4000; /** * Set the two most significant bits (bits 6 and 7) of the * clock_seq_hi_and_reserved to zero and one, respectively. */ $clock_seq_hi_and_reserved = hexdec($clock_seq_hi_and_reserved); $clock_seq_hi_and_reserved = $clock_seq_hi_and_reserved >> 2; $clock_seq_hi_and_reserved = $clock_seq_hi_and_reserved | 0x8000; return sprintf('%08s-%04s-%04x-%04x-%012s', $time_low, $time_mid, $time_hi_and_version, $clock_seq_hi_and_reserved, $node); } ---- Server IP: 64.71.164.2 Probable Submitter: 64.190.41.126 ---- Manual Page -- http://www.php.net/manual/en/function.uniqid.php Edit -- https://master.php.net/note/edit/88023 Del: integrated -- https://master.php.net/note/delete/88023/integrated Del: useless -- https://master.php.net/note/delete/88023/useless Del: bad code -- https://master.php.net/note/delete/88023/bad+code Del: spam -- https://master.php.net/note/delete/88023/spam Del: non-english -- https://master.php.net/note/delete/88023/non-english Del: in docs -- https://master.php.net/note/delete/88023/in+docs Del: other reasons-- https://master.php.net/note/delete/88023 Reject -- https://master.php.net/note/reject/88023 Search -- https://master.php.net/manage/user-notes.php