I'm trying to utilize the Amazon Product Advertising API. They provided me with a .wsdl file which I consumed and generated wrapper classes for via Visual Studio 2008's "Add Service Reference" option. This wrapper class works just fine as is and I've been successfully sending requests and receiving responses from Amazon.
However, they are now requiring that all partners start authenticating their requests. They have provided me with two .pem files (one which they call my X.509 certificate file, and one which they call my private key file). I'm not entirely sure what to do with these files. Amazon states the following:
"Each SOAP request must be signed with the private key associated with the X.509 certificate. To create the signature, you sign the Timestamp element, and if you're using WS-Addressing, we recommend you also sign the Action header element. In addition, you can optionally sign the Body and the To header element."
I realize that much more information may need to be provided here, so please let me know if I need to provide further detail in order to get an answer to this question.