Amazon Associate Web Services will start requiring API Requests to contain a cryptographic signature on August 15th. Any website that uses their Product API’s will need to be modified to correctly sign the requests using their Secret Key.
I’ve just created AmazonAPISigning.com which is a website that offers services to help in making the transition to the signed requests. Specifically, it offers a programming service to modify websites code to implement the required changes. It also offers a free API Signing service for those websites that aren’t able to implement the signatures within their own code for whatever reason. The signing service is specifically intended for widgets and tools that are implemented completely via JavaScript, and thus aren’t able to keep their private key hidden from the Javascript Source code.
The signing service may also serve as a really quick solution for webmasters to be able to start signing requests. Their website code simply needs to change the hostname used in the Amazon API requests, and the service will start calculating the signatures on their behalf.