private function addAppSecretProofModifier($appSecret)
    {
        $accessToken = $this->getModifier(static::PARAM_ACCESS_TOKEN);
        if (!$accessToken) {
            return;
        }

        $this->modifiers([
          static::PARAM_APP_SECRET_PROOF => hash_hmac('sha256', $accessToken, $appSecret),
        ]);
    }
private function addAppSecretProofModifier($appSecret)
    {
        $accessToken = $this->getModifier(static::PARAM_ACCESS_TOKEN);
        if (!$accessToken) {
            return;
        }

        $this->modifiers([
          static::PARAM_APP_SECRET_PROOF => hash_hmac('sha256', $accessToken, $appSecret),
        ]);
    }
private function addAppSecretProofModifier ( $ appSecret ) { $ accessToken = $ this -> getModifier ( static :: PARAM_ACCESS_TOKEN ) ; if ( ! $ accessToken ) { return ; } $ this -> modifiers ( [ static :: PARAM_APP_SECRET_PROOF => hash_hmac ( 'sha256' , $ accessToken , $ appSecret ) , ] ) ; }
Generate an app secret proof modifier based on the app secret & access token.

@param string $appSecret
Generate an app secret proof modifier based on the app secret & access token .