openssl_decrypt($encrypted_content, 'aes-256-cbc', $key, 0, $iv)
I have noticed that when the wrong $key is given, the result is false. php.net says
Return Values: The decrypted string on success or FALSE on failure.
What does success and failure mean? Is it guaranteed that if the wrong key is provided, the function will always return FALSE?
In other words, is it possible that a wrong key be given, and the result be a wrongly decrypted string?