Input Validation: Client-Side & Server-Side Cybersecurity Deterrent

Input Validation

The internet has outperformed expectations multiple times in terms of use-case since its launch on 1st January 1983. In 1995, Robert Metcalfe predicted that “the Internet will soon go spectacularly supernova and in 1996 catastrophically collapse”. As of April 2021, over 4.72 billion people use the internet.  

While we hope that the internet is used only for ethical and legal activities, history has shown us that the internet, though very useful, can be weaponized. One way to prevent cybersecurity compromises of any digital infrastructure is input validation.

Input Validation

an illustrative image of how websites ask you to input information which is then sent forward as a query to the software either after going through input validation or directly

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Input validation (also known as data validation) is the proper testing of any input supplied by a user or application. Input validation prevents improperly formed data from entering an information system. Input validation can be carried out on client-side and server-side code to reinforce infrastructure security.

While client-side validation is faster and favors user experience, it should not be used in isolation because client-side validation relies on the browser (which can be tricked). Client-side validation should always be used along with server-side validation as the latter is more reliable.

Client-Side Validation

Users communicate with a digital platform (mobile, web, or desktop) via forms. To register on a platform, log in, search, post, and do other activities, one has to request information from a platform or send data to a platform using forms. Regardless of how stylish the interface is, it’s still a form.

Client-side validation involves monitoring what you type to ensure that it obeys set guidelines and obtains the expected format or type of data from users. Code written to ensure users don’t deviate from what is expected of them while making requests or interacting with a digital platform is known as client-side validation.

an illustrative image of how websites ask you to input information which is then sent forward as a query to the software either after going through input validation or directly

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Client-side validation exists on the front-end and is part of the front-end secure coding requirements. It responds faster to the user’s input and reduces the latency that would exist if one only used server-side data validation. Note that client-side data validation by itself is not enough to validate data properly as it can be surmounted.

Here is an example of client-side data validation using just HTML: 

Server-Side Validation

While front-end code handles client-side input validation, back-end code handles server-side input validations. Since back-end code is the closest to the database, back-end code serves as an intermediary between the front-end code (that the user sees) and the database, which houses the user data.

When building software solutions capable of accepting and storing input from users, model/entity classes are built as the representatives of a certain category of inputs. These entity classes are present in the database like tables, interact with other tables, and send requested data back to the client.

These classes house property declarations within them (among other things) that form columns within the database tables. The columns contain specific data types, and can be manipulated to produce other data results or perform complex logical processes.

Server-side validation is done in the model/entity class by attaching attributes above the property declaration to dictate the data types that the property can accept. The specifications can encompass a lot of parameters to ensure only refined data is acceptable.

a flow chart depicting how server-side validation and client-side validation are placed within the sequence of actions that take place when a user interacts with an application and how the help secure your application and user data

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Server-side validation is slower than client-side input validation. However, server-side input validation is more reliable than client-side input validation. Thus, it’s safe to say that client-side data validation improves user experience while server-side input validation improves security.

Here’s an example of server-side input validation in Microsoft ASP.NET using C#:

Benefits of Input Validation

1. Improved User Experience

A major source of frustration for users is getting an input error when trying to make a request on a digital platform. These can be avoided by validating inputs so that users send inputs in an acceptable format and are duly warned when their inputs violate the guidelines. 

When done correctly, input validation improves user experience on a digital platform. It is the difference between platforms that users enjoy using and platforms that users avoid.

2. Increased Security

When managing internet resources that collect user data, security is of paramount concern. It can help avoid lawsuits and protect the integrity of the organization that owns the platform. 

Users who access a platform do so with an implicit trust that organizations will protect their data and use it in ethical ways.

3. Improved Error Prevention

Input validation does a lot to prevent errors from occurring. It reduces the ways in which a user can do something wrong on a digital platform, which ensures that the software performs much faster.

With proper input validation, the number of error handling codes and unit tests needed is significantly reduced. Many common mistakes are prevented by restricting the type of user inputs possible to what is expected.

4. Greater Performance

With reduced possibilities of error, a more performant software solution is more or less guaranteed. Because software programming is an exact science, it is vital to ensure the software solution obtains the data type it expects to perform in the way it’s built to operate.

5. Cleaner Data

Deep learning, machine learning, data analytics, and software engineering require a lot of data to perform efficiently. It thereby makes it imperative that clean data is gathered to make the process of feeding this data to the machine easier.

A lot of work is done by data analysts to clean up data before it’s ready for use. With input validation, the data obtained from the software is a lot cleaner, thus saving the data analysts’ time and increasing their efficiency.

Final Thoughts

Input validations are rather easy to set up. However, the impact of these validations cannot be overemphasized. The consequences for a platform without input validation can be far-reaching if compromised. Overall, understanding what validation parameters are required for a particular input is critical to ensuring proper validation is done. The use-case of most validation parameters needs to be adequately understood as it will aid proper input validation both on the client-side and the server-side.