How to Verify Apple App Store JWTs Using Elixir

The content discusses the unique method Apple uses to sign JWTs (JSON Web Signatures), which involves using certificates and a multi-tier signature validation process. It includes a tutorial on how to interact with Apple APIs and verify whether notifications from Apple's App Store are legitimate using the Elixir programming language. Andrea Leopardi shares some code snippets alongside explanations detailing the verification process, which involves first decoding the JWT's header to retrieve the necessary certificate chain. Next, Leopardi guides readers through validating this certificate chain against Apple's root certificate. Finally, the article describes verifying the signature in the JWT with the public key from the leaf certificate. While the author uses helpful Elixir libraries such as `JOSE` and `X509` to streamline the process, he emphasizes error handling and provides a convenient list of steps for the verification method. The aim is to assure developers that the features they're working on connected to the App Store are secure and reliable.