Ok. Cybersource resolved this issue for me. It's a one-line code fix in your HOP.php that is generated from the Cybersource website:

On (or around) line 32, AFTER
Code:
function cybs_sha1($in)  {
enter this
Code:
return pack ("H*", sha1($in));
I was told that the original HOP.php is appropriate for Windows servers, but this is a bug that can be fixed for Linux servers. Processing orders perfectly now.



Also - I've mentioned in another thread, but for newbs like myself - if you want Cybersource to automatically capture the sale edit the cs.php file:

On (or around) line 310, find
Code:
zen_draw_hidden_field('orderPage_transactionType','authorize') . "\n" .
and change it to
Code:
zen_draw_hidden_field('orderPage_transactionType','sale') . "\n" .
If you leave it as the word 'authorize' instead of 'sale' you'll have to make sure you log-in to Cybersource everytime you make a sale to 'capture' the charge.

Thnx Zen!