Vanessa Ramirez commented on Multipass Login Encryption in PHP

UPDATE: I got it working :) ! 

The issue was the way I was creating the encryption keys. Same issue with the signing method, I was not creating binary keys. My constructor now looks like this:

public function __construct($multipass_secret){
    ### Use the Multipass secret to derive two cryptographic keys, 
    ### one for encryption, one for signing

    $key_material = openssl_digest ( $multipass_secret, "sha256", TRUE);
    if($key_material){
        $this->encryption_key = substr($key_material,0,16);
        $this->signature_key = substr($key_material,16,16);
    }
}

I hope this helps someone that was having the same problem.