How can you validate mobile app user input securely?

1 What is user input validation?

User input validation is the process of checking and filtering the data that users enter or submit through your app's interface. It ensures that the input is valid, relevant, and safe for your app's logic and backend. User input validation can be performed on both the client-side (the app itself) and the server-side (the app's backend or API). Ideally, you should use both methods to provide a better user experience and a stronger security layer.

2 Why is user input validation important?

User input validation is important for several reasons. First, it helps you prevent errors and bugs that can affect your app's performance and functionality. For example, if you expect a user to enter a numeric value, you should validate that the input is indeed a number and not a text or a symbol. Second, it helps you protect your app from malicious attacks that can compromise your app's security and integrity. For example, if you allow users to enter comments or reviews, you should validate that the input does not contain any code or commands that can execute on your app or backend. Third, it helps you comply with the mobile app security standards and guidelines that are required by the platforms, the regulations, and the best practices in the industry.

4 How to validate user input on the server-side?

Server-side validation is the validation that occurs on the app's backend or API, after receiving the input from the client. It can be done using various techniques, such as sanitization, which is the process of removing or replacing any potentially harmful characters or symbols from the input; escaping, which is the process of adding or modifying characters or symbols that have a special meaning in the input's context; and validation rules, which are the rules that define the acceptable and unacceptable values for the input. This type of validation can enhance security by preventing or mitigating any attacks that can exploit the input. However, it can also affect performance and scalability due to increased processing and communication with the server. Therefore, it's important to optimize server-side validation by using efficient and secure methods and frameworks.

5 How to test and monitor your user input validation?

User input validation is not a one-time task, but an ongoing process that requires testing and monitoring. You should test your user input validation regularly and thoroughly, using different tools and techniques such as unit testing to verify that your validation works as expected, integration testing to check that your validation is consistent and compatible with the rest of your app, and penetration testing to assess the security and resilience of your validation and your app. Additionally, you should monitor your user input validation continuously and proactively, using tools such as logging to track and analyze your validation performance and behavior, and alerting to detect any potential problems or threats. By testing and monitoring your user input validation, you can ensure that it is effective and reliable, and that your app is secure and functional.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?