.NET HMACSHA256加密如何等效转换为PHP实现？

<code class="csharp">public static string hmacsha256(string encrypttext, string encryptkey){
    using var mac = new HMACSHA256(Encoding.UTF8.GetBytes(encryptkey));
    var hash = mac.ComputeHash(Encoding.UTF8.GetBytes(encrypttext));
    var txt = Encoding.UTF8.GetBytes(encrypttext);
    var all = new byte[hash.Length + txt.Length];
    Array.Copy(hash, 0, all ,0 , hash.Length);
    Array.Copy(txt, 0, all ,hash.Length, txt.Length);
    using var md5 = MD5.Create();
    return Convert.ToBase64String(md5.ComputeHash(all));
}</code>

<code class="php"><?php
function hmacsha256_php($encrypttext, $encryptkey) {
    $encrypted = hash_hmac('sha256', $encrypttext, $encryptkey, true);
    $encryptResult = base64_encode(md5($encrypted . $encrypttext, true));
    return $encryptResult;
}

$data = 'hello';
$secret = 'world';
$phpResult = hmacsha256_php($data, $secret);
echo "PHP加密结果: " . $phpResult . "\n";
?></code>