Sign Amazon Product Advertising API REST Requests with PHP and Python published: 08 May 2009, last updated: 29 Dec 2012 The Amazon® Product Advertising API (formerly know as Amazon Associates Webservices) can be used to access Amazon's product data for advertising purposes. By August 15, 2009, all calls to the API must be signed (with HMAC and SHA-256) to authenticate the request. I have written a