Amazon Product Advertising API Scratchpad not working
<p>So I've just been fighting shadows in the Amazon labyrinth. Went to use the <a href="http://webservices.amazon.com/scratchpad/index.html" rel="nofollow">Amazon Product Advertising API Scratchpad</a> to test out my <code>Access Key Id</code> and <code>Secret Access Key</code>, as well as entering the <code>Associate Tag</code> which isn't used in critically in the API query, just important if you want credit for the query later.</p>

<p>I kept getting the following error, no matter how many times I went and created a new set of keys or verified them in the download section of the AWS Management Console for the root user - IAM users don't work in the API seemingly.</p>

<blockquote>
  <p>Error! SignatureDoesNotMatch
  HTTP Status 403: Forbidden
  The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details.</p>
</blockquote>

<p>Rinse and repeat. Many, many times. Complete and utter frustration....</p>

<p>Lo and behold, I come across this oasis of sanity - <a href="http://associates-amazon.s3.amazonaws.com/signed-requests/helper/index.html" rel="nofollow">Signed Request Helper</a> - which provides a successful result to my query with the same keys as used above. </p>

<p>So, can anyone else confirm problems with the Scratchpad that didn't bear out in other applications, like the Signed Request Helper or their own code? At this point I'm betting that there is a bug in the Amazon Scratchpad. I guess I will go roll something to test in Python but the apparent craziness of the URL construction makes me wary. Seemingly it's soo hard even the Amazon guys got it wrong...</p>