I need to sign my Amazon Product API request, the accepted code to do this is the following.
base64_encode(hash_hmac('sha256', $request, $key, true));
This works great when I'm on 64bit Linux but fail when I'm on 64bit Windows 7. Has anyone got any ideas how to debug why hash_hmac provides different output between 64bit Linux and 64bit Windows?
Test code:
<?php
$test = "GET
webservices.amazon.com
/onca/xml
AWSAccessKeyId=00000000000000000000&ItemId=0679722769&Operation=ItemLookup&ResponseGroup=ItemAttributes%2COffers%2CImages%2CReviews&Service=AWSECommerceService&Timestamp=2009-01-01T12%3A00%3A00Z&Version=2009-01-06";
#echo $test;
echo base64_encode(hash_hmac('sha256', $test, '1234567890', true));
Edit The correct output of the code above is Nace+U3Az4OhN7tISqgs1vdLBHBEijWcBeCqL5xN9xg=
The incorrect output is X0UTct9XSJ/3k2gu6noyKhTlksx5ZbH4qAbCyW3zX48=
The non-base64-encoded values are 5f451372df57489ff793682eea7a322a14e592cc7965b1f8a806c2c96df35f8f for the incorrect and 35a71ef94dc0cf83a137bb484aa82cd6f74b0470448a359c05e0aa2f9c4df718 for the correct one when converted to hex. (it's raw binary output in the call)
Edit 2 My guess right now is that even though the Windows 7 OS is 64bit the PHP binary is compiled as 32bit as I could not find a 64bit version on the php.net site.
Edit 3 I'm actually pretty sure now that the problem is that the binary is 32bit. Most likely PHP on linux uses an OS version to calculate the hash while PHP on windows implements it's own version which causes the 32/64bit difference even though both OS are 64bit.