Beginners Guide to Build a Secure Mobile App

App security isn’t just an additional feature or a benefit – it is a core need. You may lose millions of dollars, trade secrets, intellectual property and foremost the trust of the customers. One breach will dismantle the years of trust. Even the most loyal customers with not give it a second thought before cutting the ties. That is why being proactive against this threat is pivotal from the moment you start writing the first line of code.

Every time you install an app, you end up sharing a lot of data even before you start using it. If you think about it, all types of details like your biometric data, important dates, bank details, interests, dislikes, and what not is floating about in the ether, through multiple apps. Hackers, industrial spies, and data thieves are on the continuous probe to exploit all the forms of sensitive data.

Given their pervasive nature in modern times, cyber threats are also becoming more advanced with technology. Other than personal information of the individuals, attackers are constantly on the prowl for applications exchange within big enterprises. That’s where all the sensitive information is available in bulk.

Suffice to say, with money and reputation at stake, mobile app developers need to be proactive while designing. They need to rise above the bare minimum and think ahead to build enduring security into their apps:

1. Start by penning down a Secure Code

Any hardened attacker will first probe the code for bugs and vulnerabilities to break into an application. All they need is to get their hands on a public copy of your app. From there, they will make an effort to reverse engineer your code and modify it according to their malicious intentions. Studies show that poor coding at the beginner level affects nearly 11.6 million mobile devices at any given time.

Keep the foot on the security pedal of your code while developing and make sweeps to harden your code. Your all purpose and intention should be to make it tough to breakthrough. To counterfeit reverse engineering, complicate and minify your code. Invest a lot of time in testing. Bugs are bound to show up. Fix bugs as and when they are exposed. The modular design of coding is beneficial. It will be easy to update and patch. Make a conscious effort to keep your code agile so it can be updated at the user end post a breach. Do not skimp on code hardening and code signing.

2. Persistent Data Encryption

Take all the help from the most significant mitigating factors in a data breach: encryption and automation. Every single unit of data that is exchanged over your app must be encrypted. Encryption renders plain text unreadable and vague words. Only those who have the key will be able to put it back to make sense. Share the key with only those who you trust. Even if the encrypted data is breached, there’s nothing criminals can read and misuse.

Encryption is a very powerful tool. Even the organizations like FBI and NSA seek permission to enter iPhones and access WhatsApp messages. If they can’t break through willfully, hackers sure can’t.

3. Be Extra Cautious with Libraries

It may seem like an easy way out to use third-party libraries at the time. You need to be extremely solicitous and do not skip testing the code before using them in your app. Some libraries may be poorly coded, not timely updated, and awfully insecure for your app. It is best to use controlled internal repositories. You may block direct components download from the Internet to protect your apps from vulnerabilities in libraries.

4. Authorized APIs Only

Don’t use short cuts when dealing with APIs. It is highly recommended to deploy authorized APIs only. The loosely coded ones can inadvertently grant a hacker access to sensitive information. For example, programmers can easily reuse locally cached authorization information when making API calls. However, attackers may use this loophole to capture privileges. It is easier said than done but still only use centrally authorized APIs for maximum security.

5. High-Level and Strong Authentication

Developers may claim that authentication depends on the end users of your application, but as a developer, you can encourage your users to be more sensitive towards authentication.

You can apply validations for your apps to only accept strong alphanumeric passwords that must be renewed every 45 days or three months. Multi-factor authentication is proving to be more secure. User must input a combination of static password and dynamic OTP. In the case of excessively susceptible apps, you may deploy biometric authentication like a retina scan and fingerprints. To maintain extra caution design the app to auto-sign out after a fixed interval.

6. Incorporate Tamper-Detection Technologies

Update your apps with advanced techniques to set off an alarm as soon as an attempt is made to tamper with your code or inject malicious code. Active tamper-detection works as a first and most important defensive wall against intrusion attempts. It renders the code non-functional if modified even the slightest.

7. Use the Principle of Least Privilege

The principle of least privilege dictates that a subject should gather only those permissions it absolutely needs to function and no more. Don’t go on accessing every privilege thinking just in case. Have a definitive list of minimum permissions required for it to function. If you don’t need access to the user’s media files, don’t ask for it. Refrain from making unnecessary network connections. The list goes on and varies depending on the specifics of your app. In short, perform continuous threat modeling as you update your code.

8. Use Token for Session Handling

As convenient the mobile devices are, they are that insecure. Mobile “sessions” last much longer than on desktops. Hence session handling becomes harder for the server. Instead of device identifiers, use tokens to identify a session. You can revoke both access and refresh tokens at any time, making them more secure in case the device is lost or stolen. Other practices that could be exercised are; send tokens over an encrypted channel only and verify the signature immediately upon receiving it.

9. Use the Best Cryptography Protocols

All of your hard work in encryption will pay off only with secure key management. Never hard code your keys. Use of hard-coded credentials saves time upfront but significantly impacts security. Store keys in secure containers on server and never ever store them locally on the client. As storing credentials on the device provides a stationary target. Only use latest and most trusted APIs, such as 256-bit AES encryption with SHA-256 for hashing. Modern security threats have rendered widely accepted cryptographic protocols like MD5 and SHA1, incompetent.

10. Test Over and Over

Securing your app is a never ending process. Novel threats surface and new solutions are required. Leave no stone unturned while testing your apps for vulnerabilities. Invest in penetration testing, threat modeling, and emulators. Keep an eye on new updates, fix them promptly and issue patches when required.


Data breaches are becoming a common occurrence. Latest data breach reported in October 2020 that a hacker had accessed the personal information of millions of Capital One credit card customers and card applicants probably didn’t shock all that many people. Although affecting millions, sadly it is not even in top 10 data breach incidents. Reason again was poor security standards.

Lay equal emphasis on security of apps as usability and aesthetic appeal. It’s time take notice of the importance of cyber security. Hope you will follow above guidelines to keep your apps as secure as Fort Knox.