Encrypting cookies with Angular Universal and Node.js is a crucial step in protecting user data from unauthorized access. By using encryption techniques, developers can ensure that sensitive information, such as authentication tokens and user secrets, are protected from being compromised by malicious users. In this post, Maciej Treder demonstrates how to encrypt cookies in an Angular Universal and Node.js application, using the cryptography library in OpenSSL to perform the encryption and decryption. The author provides a step-by-step guide on how to implement cookie encryption, including generating a private RSA key, encrypting the authentication cookie, and decrypting the user's secret data. By following these steps, developers can protect their applications from unauthorized access and ensure that user data remains confidential.