Guide to Verifying Slack Requests in a Phoenix Application

This article by Benj Reinhart provides a comprehensive guide on how to verify Slack requests in a Phoenix application. It begins by outlining the necessary background, including the setup of initial routes and controllers. The main focus is on verifying the authenticity of requests from Slack’s Events API using cryptography. It details the steps to compute and compare signatures, handle replay attacks, and preserve the unmodified request body for accurate verification. Additionally, the article provides sample code snippets to illustrate the implementation of custom plugs and middleware for verifying timestamps and request signatures. The end goal is to ensure that only legitimate requests from Slack are processed by the server.