The documentation is very misleading then. This page, for example,
states that accept hosted requires the use of a signature key:
https://support.authorize.net/s/article/Authorize-Net-Integration-Methods-Explained
Also, the integration documentation ...
I'm trying to use the accept hosted product with an embedded iframe, and
because this method sends its response via the iframe communicator I
need to use the transHashSha2 value to protect against spoofing (e.g. by
injection from a malicious customer...
