What is API encryption?

Melinda Gutermuth

February 6, 2024

API encryption is the process of encoding data that is sent between a client and an API in order to prevent unauthorized access or tampering. API encryption, which typically uses cryptographic algorithms, secures the API by safeguarding its data from interception, hacking, and other cyberattacks.

In this blog post, we’ll discuss the important role that API encryption plays in an API-first world, common challenges with API encryption, and how Postman can help you implement a strong API encryption strategy.

How does API encryption work?

API encryption prevents unauthorized parties from reading data that is transmitted between a client (like a web browser or mobile app) and an API server. This process usually involves cryptographic protocols, with Secure Sockets Layer/Transport Layer Security (SSL/TLS) being the most widely used. When a client sends a request to an API, the SSL/TLS protocol creates a secure communication channel by performing a “handshake.”

How does a TLS handshake work?

1. Client hello: The client initiates the handshake by sending a message to the server, specifying which TLS versions and cipher suites it can support. A cipher suite includes the client’s preferred encryption algorithms (such as AES, DES, or RC4), message authentication code (MAC) algorithms, key exchange methods such as RSA, Diffie-Hellman (DH), or Elliptic Curve Diffie-Hellman (ECDH), and hashing algorithms.
2. Server hello: In response to the client’s message, the server chooses a cipher suite that is compatible with both the client and the server. This message also includes the server’s SSL certificate along with a public key to verify its authenticity.
3. Verifying the certificate: The client checks the server’s SSL certificate to ensure that it was issued by a trusted Certificate Authority (CA). This confirms that the server has the private key that corresponds to its public key, indicating that the server is who it claims to be.
4. Exchanging keys: Depending on the exchange method they choose, either the client generates a pre-master secret, encrypts it with the server’s public key, and sends it to the server (RSA), or the client and server exchange parameters to compute a shared secret (DH or ECDH).
5. Deriving session keys: The client and server use the pre-master secret (if using RSA) or the shared secret (if using DH or ECDH) to derive session keys. These session keys include the master secret, which is used to derive all other session keys; encryption keys, which encrypt and decrypt the data; and MAC keys, which handle message authentication and data integrity checks.
6. Completing the handshake: The client and server exchange a message that is encrypted using the derived session keys to confirm that the handshake is complete. At this point, data can be exchanged between the client and the server.

Whether a request is made to the API directly by a user or via a mobile or web application, the TLS handshake process remains the same. The TLS handshake is a key component of API encryption, as it enables secure communication between clients and API servers by establishing encrypted connections, verifying server authenticity, and protecting data during transmission. This ensures that sensitive information exchanged through APIs is kept confidential and safe from interception or tampering by unauthorized parties.

What is the difference between API encryption and API authentication?

When it comes to securing APIs, authentication and encryption are separate but related concerns. API encryption protects data in transit between a client and an API server to make sure the data remains confidential and unchanged. On the other hand, API authentication is about verifying the identity of the users or systems that are trying to access the API. Using technologies like JSON Web Tokens (JWT), OAuth tokens, and API keys, authentication determines whether a request is coming from a valid source.

Authentication acts as a gatekeeping mechanism by guaranteeing that only authorized users can access the API, while encryption protects data from being intercepted or tampered with. Both are necessary for API security, as they address different security needs within the ecosystem.

Why is API encryption important?

Encryption is an essential tool for protecting sensitive information, especially when dealing with financial transactions, personal details, and confidential business data. It protects against unauthorized parties reading, intercepting, or tampering with this data during transmission. If this data were not encrypted, it would be open to common cyberattacks such as man-in-the-middle attacks, data breaches, and eavesdropping.

In addition to being a technical requirement, API encryption is a legal or compliance mandate in many industries. Encryption plays a crucial role in promoting and maintaining consumer trust in digital services while also ensuring that privacy standards are met. Secure API encryption is an absolute necessity for establishing confidence in API-based services.

Why do APIs get attacked?

APIs are often the target of cyberattacks because they serve as entry points to valuable and sensitive data. APIs handle a wide range of data, including financial information, business-critical data, and personal user details, acting as intermediaries between various software applications and services. Because of this, attackers looking to exploit weaknesses for fraud, data theft, or service interruption find them to be lucrative targets.

Modern digital infrastructures rely on APIs, which makes them more vulnerable due to their prevalence and importance. Many APIs are susceptible to attacks because they are publicly accessible via the internet. APIs can also have security weaknesses that attackers can exploit, such as inadequate authentication, insufficient input validation, or flawed business logic. Because APIs are increasingly used for core business functions, compromising an API can cause significant operational and reputational damage to a company.

What are the challenges of API encryption?

One of the primary challenges of API encryption is the complexity of implementation and management. In particular, it can be difficult to ensure that encryption protocols are configured and maintained correctly. This includes choosing the right encryption methods, managing encryption keys, and maintaining compatibility across different systems and platforms. Because the process of encrypting and decrypting data increases response times and consumes more resources, encryption can also affect performance. Balancing security and performance is critical, especially for high-traffic APIs.

Another challenge is staying ahead of new security threats and vulnerabilities. Outdated encryption can become a security liability, so staying up-to-date requires ongoing vigilance and adaptability. Managing and consistently implementing encryption in distributed environments, such as microservices, can increase the complexity even further. A proactive and cautious approach to API encryption can assist in overcoming these obstacles and ensuring efficient and effective data protection.

What are some best practices for API protection?

This section describes some best practices for protecting an API that go beyond API encryption.

• Use authentication and authorization to verify user identities and restrict access to resources and data. For authentication, confirm user identities with tokens, OAuth, or API keys. For authorization, configure roles and permissions to control what authenticated users can do.
• Encrypt API data with SSL/TLS to prevent interception and tampering. Secure data transfers over HTTPS by deploying an SSL/TLS certificate on the server.
• Implement API quotas and throttling to manage server load and prevent abuse and service disruptions. Quotas limit the number of requests a user can make in a given timeframe, while throttling controls the rate of incoming requests.
• Use tokens to maintain session information. JWT can store user information and permissions, providing a stateless way to verify user identities and manage access rights.
• Use an API gateway to centralize API security, traffic, and authentication. An API gateway streamlines rate limiting, request routing, and access control, improving security and performance.
• Use API auditing and logging to track user, request, and system behavior. This practice records API transaction details like access times, request types, and user identities to identify operational and security risks.
• Keep your APIs up-to-date. Updates often fix security vulnerabilities and boost performance, protecting the API from new threats and exploits while ensuring its security and efficiency.
• Use a web application firewall (WAF) to filter and monitor HTTP traffic. A WAF runs rules on incoming traffic to prevent common threats like SQL injection and XSS.

How can Postman help with API encryption?

The Postman API Platform can help with API encryption in a variety of ways. For example, Postman allows developers to easily set up and test HTTPS requests. HTTPS applies SSL/TLS encryption to safeguard data while it is being transmitted between the client and the server, which ensures that any sensitive data is encrypted and less vulnerable to interception or tampering.

In addition, Postman has tools that can safely manage and store environment variables. Any sensitive information needed for encrypted API interactions, such as API keys or tokens, can be stored in these variables. By using variables, developers can avoid hard-coding sensitive information into their requests, reducing the risk of exposure. Postman also enables sharing collections and environments with other team members without exposing sensitive information, which is essential for secure development practices.

Postman improves API encryption capabilities by facilitating secure request handling, enabling collaboration while protecting sensitive data, and ensuring that encryption standards such as HTTPS are correctly implemented and tested.