Hi Ben,
The server protocol does not specify the format that is to be used for input.
In order to understand the syntax of "{input}", you can have a look at the Conventions paragraph:
{...}: utf8 strings or raw data, suffixed with a \00 byte. To avoid confusion with this end-of-string byte, all transferred \00 and \FF bytes are prefixed by an additional \FF byte.
Maybe you don’t take care of 00 and FF bytes in the input yet?
Best, Christian