Thanks @Renaissance, but it took @cwdsl so long to figure out that
solution, and it's so complicated, it scared me off. It took me a few
days just to get @stw's far simpler solution to work :-(
For our DPM website, we used @stw's solution, instead of @Renaissance's,
because Renaissance's requires the latest AuthorizeNet PHP library,
which requires PHP version 5.6, which would require re-writing our
entire website. In step 1, stw's solution ...
Here's a correction to @stw's PHP SIM solution In step 1, base_convert
does not work. For PHP 5.4+, use instead:hex2bin(SIGNATURE_KEY);as
suggested by @Renaissance For earlier versions of PHP, you can
use:pack("H*" , SIGNATURE_KEY)
