An API, or Application Programming Interface, is a set of protocols that allows different systems and services communicate with each other. An unsecured API can lead to unauthorized access to sensitive data, disruption of services, and substantial financial and reputational damage. Securing APIs is not just important, it's essential for protecting data and maintaining trust.

In this article, we are going to discuss the best practices of API security and why it is important to protect your data in transit.

Importance of data protection in transit

Data is always going to be moved from one point to another, that's the whole basis of building applications. When data is in transit it has to be protected at all times. If unprotected it is vulnerable to interception and tampering by attackers, leading to risks such as exposure of sensitive information and system disruption.

Why protect data in transit?

The following are some of the reasons why data must be protected while in transit.

• Prevent eavesdropping
• Ensure data integrity
• Compliance

Let's expand on these points.

Prevent eavesdropping

Malicious attackers can intercept unprotected data, exposing sensitive information such as:

• Passwords
• Personal information
• Financial details and records
• Private medical records

For instance, imagine a customer making an online purchase. As their credit card information is transmitted to the merchant's system, it could be intercepted by an attacker on the network. This could lead to identity theft, fraudulent charges, and significant financial loss for the victim.

By ensuring use of strong encryption protocols, organizations can render intercepted data unusable, safeguarding sensitive information from attackers.

Data integrity

Data integrity in transit ensures that information remains accurate and untouched as it moves between systems.

Imagine a hacker intercepts a medical prescription transmitted between a doctor and a pharmacy. By subtly altering the dosage or the medication itself, they could potentially endanger a patient's life. This scenario highlights the critical importance of data integrity in transit. Unsecured data is vulnerable to modification, leading to fraudulent transactions, data corruption, and the spread of misinformation. For example, attackers can manipulate financial transactions, compromise critical systems, or even spread false information in sensitive areas like healthcare and finance.

Compliance

Numerous data protection regulations, such as the General Data Protection Regulation (GDPR) impose strict requirements on how organizations handle and transmit personal data. Failure to comply with these regulations can result in hefty fines, legal repercussions, and damage to an organization's reputation.

For example, an European e-commerce company that transmits customer data to a third-party service provider without adequate security measures could face significant fines under GDPR. By prioritizing data protection in transit, organizations can demonstrate their commitment to regulatory compliance and safeguard their operations.

Key elements of API security

Secure authentication and access control

Always make sure only authenticated users can access the API, and enforce that using standard authentication methods and models. The usual suspects include OAuth 2, which is a widely-used authorization framework that provides secure token-based access; API keys, which are unique identifiers that grant access to specific API resources; and basic authentication, which is a simple yet effective method using username and password credentials.

For example, imagine building a financial savings app where users log in to view their account balance. Authentication ensures that the person attempting to access the account is genuinely the account holder. This process verifies identity, ensuring that sensitive information like account balances is only available to the right user.

const authenticateToken = (req, res, next) => {
    const token = req.headers['authorization'];
    if (!token) return res.status(403).json({ error: 'No token provided' });

    jwt.verify(token, process.env.JWT_SECRET, (err, user) => {
        if (err) return res.status(401).json({ error: 'Invalid token' });
        req.user = user;
        next();
    });
};

API key management

Think about API keys like the keys to your house. They provide access to your personal space, so you must manage and protect them with care to keep your home secure.

Firstly, imagine if you left your house key under the welcome mat. It's an obvious spot, making it easy for anyone to find and enter your home without permission. Similarly, hard-coding API keys directly into your application code is like leaving the key in plain sight. Instead, keep them safe in a secure place, like a key safe (environment variables or secrets management systems), to prevent unauthorized access.

If you've ever lost a key or had a break-in at your house, you would obviously want to change your house keys. Regularly rotating your API keys works the same way. By updating your keys periodically, you ensure that, even if an old key is compromised, it can no longer be used reducing the risk of unauthorized access.

You know how you always double-check who you give your house key to? You wouldn't hand it out to just anyone. Instead, you only share it with trusted family members or close friends. In the same way, with API keys, it’s important to implement access controls, allowing only authorized personnel to use them. This limits the risk of someone misusing the key and gaining access to sensitive information.

Managing API keys is much like managing your house keys secure storage, regular updates, and limiting access keep your systems safe and sound.

In our hypothetical financial savings app, you can set up a .env file and manage your keys.

JWT_SECRET=<your_jwt_secret_key>
DATABASE_URL=<your_database_connection_string>
API_KEY=<your_api_key>

Encryption of data in transit

All data must be encrypted during transmission to avoid interception. You can use Transport Layer Security (TLS) a widely-used protocol that encrypts data, ensuring confidentiality and integrity.

A good example where this can be desmostrated is with a mobile banking app that transmits sensitive financial information, such as account balances and transaction history, over the internet. By using TLS, the app encrypts the data during transmission, making it unreadable to any unauthorized party who may intercept the communication. This protects users' sensitive information from any potential cyberattacks.

Additionally, consider implementing HTTPS (HTTP over TLS) to encrypt web traffic, ensuring that all communication between the client and the server is secure.

Best practices for securing data in transit

Using HTTPS (TLS)

To ensure the confidentiality and integrity of data transmitted between your API and clients, HTTPS should always be impelemented. This protocol encrypts data using TLS, rendering it unreadable to eavesdroppers. By implementing HTTPS, you create a secure communication channel that protects sensitive information from interception and manipulation.

In our savings app API example, enabling HTTPS involves obtaining a valid TLS certificate from a trusted Certificate Authority (CA). This certificate acts as a digital identity for your server, allowing browsers to verify its authenticity.

const https = require('https');
const fs = require('fs');
const app = require('./app'); // Your API app

const options = {
    key: fs.readFileSync('path/to/private.key'),
    cert: fs.readFileSync('path/to/certificate.crt')
};

https.createServer(options, app).listen(443, () => {
    console.log('Secure API running on port 443');
});

Encrypting sensitive data

While HTTPS offers a foundation for data security in transit, you should consider adding another layer of protection by encrypting sensitive data at the application level before transmission. This provides an extra shield, making intercepted data even more unintelligible to attackers.

Algorithms like AES-256 (Advanced Encryption Standard) are industry-standard for this purpose. AES-256 offers standard encryption with a 256-bit key length, making it extremely difficult to crack through brute force attacks.

Imagine our savings app API needs to transmit user data, including account balances and transaction history. While HTTPS secures the communication channel, we can also encrypt this sensitive data at the application level with AES-256 before sending it over the network.

const crypto = require('crypto');
const encrypt = (data, secretKey) => {
    const cipher = crypto.createCipheriv('aes-256-cbc', secretKey);
    let encrypted = cipher.update(data, 'utf8', 'hex');
    encrypted += cipher.final('hex');
    return encrypted;
};

const sensitiveData = encrypt(JSON.stringify(userData), process.env.SECRET_KEY);
res.json({ data: sensitiveData });

Implementing API threat protection

You should always prioritize protecting your API from potential threats to maintain security and integrity of your application. let's say our savings app API is a gateway for users to access their financial data it is important that the API is protected from various threats. You should adopt a layered security approach.

Start by using API Gateways, which act as a security checkpoint. They enforce access controls to ensure only legitimate users interact with your API. Additionally, API Gateways can implement rate limiting to prevent abuse and help mitigate Distributed Denial of Service (DDoS) attacks by controlling the number of requests a user can make. They also include bot detection to block automated scripts from exploiting your API.

You can also integrate Web Application Firewalls (WAFs) into your security strategy. A WAF is like a shield that filters incoming traffic and blocks malicious requests. It protects your API from common vulnerabilities such as SQL injection, where attackers try to manipulate your database through your API, and cross-site scripting (XSS), where malicious scripts are injected into your application.

You should maintain security monitoring and logging to keep a close watch on API traffic. By continuously monitoring for anomalies and suspicious activity, you can quickly identify and respond to potential threats.

Together, these measures create a strong defense system for your API, ensuring that it remains secure and protected at all times.

API authentication and authorization

Authentication and authorization are two important layers of API security. While authentication ensures that a user is who they claim to be, authorization defines what actions the authenticated user can perform within your API. Implementing this dual-layer security ensures that sensitive data and functionalities are accessed only by users with the right permissions.

In our financial savings app, Role-Based Access Control (RBAC) is a practical approach to manage these permissions. RBAC assigns permissions based on pre-defined roles. For instance, an admin might have the ability to approve transactions, while a regular user can only view their account balance. clearly seprating the roles helps maintain the integrity and security of the system.

Attribute-Based Access Control (ABAC) offers even finer control by considering dynamic attributes such as user role, location, device type, or specific data being accessed. This flexibility allows for more granular permissions tailored to various conditions and scenarios.

Let’s implement this in our financial savings app using Cerbos' RBAC model, which is detailed in our article on how to implement RBAC authorization. Here’s an example of how we can enforce that only admins can approve transactions:

const authorize = (roles) => (req, res, next) => {
    if (!roles.includes(req.user.role)) {
        return res.status(403).json({ error: 'Access denied' });
    }
    next();
};

// Usage: Only admin can approve transactions
app.post('/approve-transaction', authenticateToken, authorize(['admin']), (req, res) => {
    // Transaction approval logic
});

This function checks the user’s role before allowing them to proceed with certain actions. In our case, if the user isn’t an admin, they’ll receive an "Access denied" error. By integrating such RBAC mechanisms, we ensure that only users with the right level of authority can perform sensitive operations, keeping the app secure and well-structured.

Use API rate limiting and throttling

To protect your API from abuse and potential denial-of-service (DoS) attacks, it is important to implement rate limiting and throttling mechanisms. These techniques help control the rate at which clients can make requests to your API, preventing excessive traffic and resource exhaustion.

Rate Limiting

There are many rate limiting techniques. A common technique is "Fixed Window Rate Limiting", which limits the number of requests that can be made within a specific time window, such as 60 seconds. Another is "Sliding Window Rate Limiting", which controls the number of requests within a moving time window, offering more flexibility compared to fixed window. There's also the "Token Bucket Algorithm", which permits short bursts of traffic while maintaining a consistent rate limit over time.

Our hypothetical app we can use the express-rate-limit library in Node.js:

const rateLimit = require('express-rate-limit');

const limiter = rateLimit({
    windowMs: 15 * 60 * 1000, // 15 minutes
    max: 100, // Limit each IP to 100 requests per window
    message: 'Too many requests from this IP, please try again later.'
});

app.use('/api', limiter);

By implementing rate limiting, you can ensure that your API remains responsive and resilient, even under heavy load or malicious attacks.

Conclusion

API security is not optional in modern day application development. Protecting data in transit is a key component of a secure system, and implementing practices like HTTPS, encryption, and secure authentication ensures the integrity and confidentiality of your API. By following these best practices, you can secure your APIs against malicious attacks, safeguard user data, and build trust with your users. Start implementing these best practices in your projects today, and happy coding!