Amazon Simple Queue Service
Developer Guide

Query Request Authentication

When you programmatically call the functionality exposed by the Amazon SQS API, all calls sent to Amazon SQS must be signed. If you use an AWS SDK, the SDK handles the signing process for you so that you don't have to manually complete the tasks. On the other hand, if you submit a Query request over HTTP/HTTPS, then you must include a signature in every Query request.

Amazon SQS supports Signature Version 4. Signature Version 4 provides improved security and performance over previous versions. If you're creating new applications that use Amazon SQS, then you should use Signature Version 4.