PHP byteArray?

gistfile1.php

<?php

/** @link http://madskristensen.net/post/A-shorter-and-URL-friendly-GUID.aspx */
function fromBase64($input) {
    $segments = unpack('C*', base64_decode(str_replace(array('_', '-'), array('/', '+'), $input)));

    array_walk($segments, function(&$segment, $key) {
        $segment = dechex($segment);
    });

    list ($a, $b, $c, $d, $e) = array(
        unpack('I*', pack('H*', implode('', array_slice($segments, 0, 4)))),
        unpack('n*', pack('H*', implode('', array_slice($segments, 4, 2)))),
        unpack('n*', pack('H*', implode('', array_slice($segments, 6, 2)))),
        unpack('n*', pack('H*', implode('', array_slice($segments, 8, 2)))),
        array(hexdec(implode('', array_slice($segments, 10)))),
    );

    $result = '';
    foreach (array($a, $b, $c, $d, $e) as $segment) {
        $result .= dechex(end($segment));
        $result .= '-';
    }

    return rtrim($result, '-');
}

function toBase64($input) {

    $segments = explode('-', $input);

    list ($a, $b, $c, $d) = array(
        pack('I*', hexdec($segments[0])),
        pack('n*', hexdec($segments[1])),
        pack('n*', hexdec($segments[2])),
        pack('n*', hexdec($segments[3])),
    );

    $e = str_split($segments[4], 2);
    array_walk($e, function(&$byte, $key){
        $byte = pack('c', hexdec($byte));
    });

    $e = implode('', $e);

    $result = implode('', array($a, $b, $c, $d, $e));
    $result = base64_encode($result);
    $result = str_replace(array('/', '+'), array('_', '-'), $result);
    $result = rtrim($result, '=');

    return $result;
}

// Main

$options = getopt("edt");

if (isset($options['e'])) {
    printf("Input => %s => Output => %s\n", $argv[2], toBase64($argv[2]));
    exit(1);
} elseif (isset($options['d'])) {
    printf("Input => %s => Output => %s\n", $argv[2], fromBase64($argv[2]));
    exit(1);
} elseif (isset($options['t'])) {
    $dataProvider = array('c9a646d3-9c61-4cb7-bfcd-ee2522c8f633');
    for ($i = 30; 0 !== $i; --$i) {
        $dataProvider[] = sprintf(
            '%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
            mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff),
            mt_rand(0, 0x0fff) | 0x4000,
            mt_rand(0, 0x3fff) | 0x8000,
            mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff)
        );
    }

    foreach ($dataProvider as $guid) {
        $encoded = toBase64($guid);
        $decoded = fromBase64($encoded);
        $mask = "%30s >> %-0.40s << %40.40s = %2s\n";
        printf($mask, $guid, $encoded, $decoded, ($decoded === $guid) ? "\033[0;32m ✓ \033[0m" : "\033[0;31m ✘ \033[0m");
    }

    exit(1);
} else {
    printf("Usage: %s [-d|-e|-t] [string]\n", ltrim($argv[0], './'));
    exit(0);
}