Generating a RFC 4211 compliant valid UUID or GUID string with PHP

15/03/2017 - PHP

You can use class below to generate a RFC 4211 compliant valid Universally Unique IDentifier (UUID) or GUID strings. It is useful if you don't want to use auto-incremented integer IDs for the records in database. This class is taken from UUID so it is not my work. Just keeping a record of it. You never know, it might vanish one day!


Class


class UUID
{
    const COMMON_NAMESPACE = '64566f3d-9c52-4589-b7d9-82d1a22e18a3';

    public static function v3($namespace, $name)
    {
        if (!self::is_valid($namespace)) {
            return false;
        }

        // Get hexadecimal components of namespace
        $nhex = str_replace(array('-', '{', '}'), '', $namespace);

        // Binary Value
        $nstr = '';

        // Convert Namespace UUID to bits
        for ($i = 0; $i < strlen($nhex); $i += 2) {
            $nstr .= chr(hexdec($nhex[$i].$nhex[$i+1]));
        }

        // Calculate hash value
        $hash = md5($nstr.$name);

        return sprintf(
            '%08s-%04s-%04x-%04x-%12s',
            // 32 bits for "time_low"
            substr($hash, 0, 8),
            // 16 bits for "time_mid"
            substr($hash, 8, 4),
            // 16 bits for "time_hi_and_version",
            // four most significant bits holds version number 3
            (hexdec(substr($hash, 12, 4)) & 0x0fff) | 0x3000,
            // 16 bits, 8 bits for "clk_seq_hi_res",
            // 8 bits for "clk_seq_low",
            // two most significant bits holds zero and one for variant DCE1.1
            (hexdec(substr($hash, 16, 4)) & 0x3fff) | 0x8000,
            // 48 bits for "node"
            substr($hash, 20, 12)
        );
    }

    public static function v4()
    {
        return sprintf(
            '%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
            // 32 bits for "time_low"
            mt_rand(0, 0xffff), mt_rand(0, 0xffff),
            // 16 bits for "time_mid"
            mt_rand(0, 0xffff),
            // 16 bits for "time_hi_and_version",
            // four most significant bits holds version number 4
            mt_rand(0, 0x0fff) | 0x4000,
            // 16 bits, 8 bits for "clk_seq_hi_res",
            // 8 bits for "clk_seq_low",
            // two most significant bits holds zero and one for variant DCE1.1
            mt_rand(0, 0x3fff) | 0x8000,
            // 48 bits for "node"
            mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff)
        );
    }

    public static function v5($namespace, $name)
    {
        if (!self::is_valid($namespace)) {
            return false;
        }

        // Get hexadecimal components of namespace
        $nhex = str_replace(array('-', '{', '}'), '', $namespace);

        // Binary Value
        $nstr = '';

        // Convert Namespace UUID to bits
        for ($i = 0; $i < strlen($nhex); $i += 2) {
            $nstr .= chr(hexdec($nhex[$i].$nhex[$i+1]));
        }

        // Calculate hash value
        $hash = sha1($nstr.$name);

        return sprintf(
            '%08s-%04s-%04x-%04x-%12s',
            // 32 bits for "time_low"
            substr($hash, 0, 8),
            // 16 bits for "time_mid"
            substr($hash, 8, 4),
            // 16 bits for "time_hi_and_version",
            // four most significant bits holds version number 5
            (hexdec(substr($hash, 12, 4)) & 0x0fff) | 0x5000,
            // 16 bits, 8 bits for "clk_seq_hi_res",
            // 8 bits for "clk_seq_low",
            // two most significant bits holds zero and one for variant DCE1.1
            (hexdec(substr($hash, 16, 4)) & 0x3fff) | 0x8000,
            // 48 bits for "node"
            substr($hash, 20, 12)
        );
    }

    public static function is_valid($uuid)
    {
        return preg_match(
            '/^\{?[0-9a-f]{8}\-?[0-9a-f]{4}\-?[0-9a-f]{4}\-?[0-9a-f]{4}\-?[0-9a-f]{12}\}?$/i', $uuid
            ) === 1;
    }
}

Usage


// name-based and hashed with MD5
echo $v3uuid = UUID::v3('1546058f-5a25-4334-85ae-e68f2a44bbaf', 'SomeRandomString');
echo $v3uuid = UUID::v3(UUID::COMMON_NAMESPACE, 'SomeRandomString');
echo $v3uuid = UUID::v3(UUID::COMMON_NAMESPACE, 'SomeRandomString');

// name-based and hashed with SHA1
echo $v5uuid = UUID::v5('1546058f-5a25-4334-85ae-e68f2a44bbaf', 'SomeRandomString');
echo $v5uuid = UUID::v5(UUID::COMMON_NAMESPACE, 'SomeRandomString');
echo $v5uuid = UUID::v5(UUID::COMMON_NAMESPACE, 'SomeRandomString');

// Always random
echo $v4uuid = UUID::v4();

Result


643dc989-58e9-3e72-9fd5-e3b4a09b62e9
cbf4f776-76b4-354f-b58b-4e6f40531181
cbf4f776-76b4-354f-b58b-4e6f40531181

c8333619-8220-5b21-b5d9-2bd56713675a
8b731897-178b-5abb-be50-ebb69f9d848c
8b731897-178b-5abb-be50-ebb69f9d848c

e8268b3e-449c-4e49-87ff-82db2da75715