PHP AES 256 CBC : Decrypt Plain Text

<?php

    $key = "74b8d8e7f552f49a9f59642db34ce5601dcb726b52e0";

    $ciphertext = "OeNa+bCeII57X0hSf0IBZLSYed5SUGSEOZMocYDzyTNlO0MRervabo/CbIbHsv3vpVaLhFHBd9j06MuR9VMQmmNp8N9h4f8HIC5m768RbDXi1O05Yxky7gl4EPTMYphnsBu3flqUQwzjJd3YBJJf/Q==";

    $c = base64_decode($ciphertext);

    $ivlen = openssl_cipher_iv_length($cipher="AES-256-CBC");

    $iv = substr($c, 0, $ivlen);

    $hmac = substr($c, $ivlen, $sha2len=32);

    $ciphertext_raw = substr($c, $ivlen+$sha2len);

    $original_plaintext = openssl_decrypt($ciphertext_raw, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);

    $calcmac = hash_hmac('sha256', $ciphertext_raw, $key, $as_binary=true);

    if (hash_equals($hmac, $calcmac)){

        echo $original_plaintext."\n";
    }


?>