Saved from https://stackoverflow.com/questions/44793365/how-to-use-laravels-validation-rule-in-custom-validation-rule

encrypted_unique

Validator::extend('encrypted_unique', function ($attribute, $value, $parameters, $validator) {
    list ($table, $column, $ignore_id) = $parameters; // or hard-coded if fixed
    $count = $validator->getPresenceVerifier()->getCount($table, $column, encrypt($value), $ignore_id);
    return $count === 0;
});

'identifier' => "encrypted_unique:table,column,$this_id"