Building Secure RESTful APIs with NestJS: A Practical Guide/

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Implement a Login Endpoint with a JWT

Implement a Login Endpoint with a JWT

Build on the fundamentals of JWTs by implementing a login endpoint.

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In this lesson, we’ll explore JWTs and understand their role in NestJS applications. A JWT serves as a secure means to transmit information between parties in the form of a JSON object. This lesson will cover the basics of a JWT, as well as its structure, generation, and implementation in a NestJS application.

What is a JWT?

A JWT is a compact, self-contained method for securely transmitting information between parties. It is widely used for user authentication and authorization in web applications and APIs.

Structure of a JWT

A JWT consists of three main components: a header, a payload, and a signature. These components are Base64-encoded and separated by periods, ensuring secure transmission and storage.

To achieve compactness and safe transmission, all three parts are Base64-encoded. Base64 encoding is a method of encoding binary data into plain text using ASCII string format. This ensures that the encoded data is safe for transmission and storage. In the context of JWTs, Base64-encoded strings are URL-friendly, meaning they do not contain problematic characters in URLs. This makes it easy to include web URLs as query parameters in JWTs.

For example, we can have a JWT with the payload given below:

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{
  "email": "john+doe@example.com",
  "exp": 1677644570
}
// Base64 encode
ewogICJlbWFpbCI6ICJqb2huK2RvZUBleGFtcGxlLmNvbSIsCiAgImV4cCI6IDE2Nzc2NDQ1NzAKfQ==

The payload above contains an email with a “+” character, which might be misinterpreted due to URL encoding. With Base64, the “+” character in the email address is encoded correctly. This ensures that the resulting JWT is URL-safe and can be safely included in the HTTP requests without causing issues. ...