Data Encryption in PHP - php

Question

I was hoping someone would be able to clarify something for me. I have a class to encrypt data and I also use the code to make it into functions instead of a class. Now they use the same keys and everything but if I encrypt something using the class I cannot decrypt using the function why is this? is it one way more secure than the other?
this is the class
class Encryption {
var $secret_key;
var $key;
public function __contruct(){
$this->secret_key = 'MYSECRETKEY12345654321';
// hash
$this->key = hash('sha256', $this->secret_key);
}
public function encode($value){
$output = openssl_encrypt($value, 'AES-256-CBC', $this->key, 0, substr(hash('sha256', "0ac35e3825857c810f86e384d1ac59e8"), 0, 16));
$output = base64_encode($output);
return $output;
}
public function decode($value){
return openssl_decrypt(base64_decode($value), 'AES-256-CBC', $this->key, 0, substr(hash('sha256', "0ac35e3825857c810f86e384d1ac59e8"), 0, 16));
}
}
this is the function
function encrypt($value)
{
$secret = 'MYSECRETKEY12345654321';
$key = hash('sha256', $secret);
$output = openssl_encrypt($value, 'AES-256-CBC', $key, 0, substr(hash('sha256', "0ac35e3825857c810f86e384d1ac59e8"), 0, 16));
$output = base64_encode($output);
return $output;
}
function decrypt($value)
{
$secret = 'MYSECRETKEY12345654321';
$key = hash('sha256', $secret);
return openssl_decrypt(base64_decode($value), 'AES-256-CBC', $key, 0, substr(hash('sha256', "0ac35e3825857c810f86e384d1ac59e8"), 0, 16));
}
code example
$encrypt = new Encryption();
$private = $encrypt->encode(10);
$public = decrypt($private);//this will return false;