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Application Level Encryption Security Guarantees

At first glance, encrypting data at the application level may seem like the best strategy for securing data. It requires you to implement specific data protections within each application rather than simply encrypting all data on a disk, database, or file system. Wouldn’t it be simpler and less risky to apply encryption at higher levels of your software stack?

The answer is that encrypting data at layers other than the application may be simpler, but it’s not always as secure. Application-level encryption delivers benefits that other types of encryption strategies cannot.

To understand why, keep reading for an overview of the special security guarantees that application-level encryption provides.

What Is Application-Level Encryption?

Application-level encryption is the use of data controls within an application to encrypt information that is stored, managed, or processed by the application.

Put another way, application-level encryption is the opposite of encrypting data at the network transport layer using a protocol like TLS, or encrypting it at the database or file system layer through schemes like AES.

It’s worth noting that application-level encryption can be implemented in a variety of ways, some of which overlap with other encryption techniques. For instance, application-level encryption could involve using application logic to encrypt data that is processed or stored on client devices, in which case it would also be a form of client-side encryption. Or, application-level encryption that encrypts data on both servers and client devices would be an example of end-to-end encryption.

Thus, don’t think of application-level encryption as an alternative to other popular encryption techniques. Instead, it’s a complement to them, or a means of implementing them.

The Growing Interest in App-Level Encryption

Historically, application-level encryption was not a common data encryption technique. The main reason why is that devising a means of encrypting data within each application can increase the amount of work that developers need to perform: you have to build data protection logic into the app and maintain the code associated with it indefinitely.

In comparison, simply deploying a tool that can encrypt all data that passes over the network and all data that is stored at rest in a file system or database is relatively simple. It requires no special coding, and the tools are easier to maintain over time.

That’s why, traditionally, few applications implemented built-in encryption.

Why Application-Level Encryption? And Why Now?

However, several factors have changed over the past decade, leading to a surge of interest in application-level encryption.

  • Fast-changing environments: Modern applications typically run in highly dynamic, distributed environments. The specific servers that host an application could change from one moment to the next. So could its network configurations and routes. Under these conditions, trying to manage encryption at the infrastructure level is challenging, because the infrastructure is not very static.
  • Dynamic storage models: Ten years ago, most data lived in one of two places: a file system or a database. Today, data could also live in an object storage bucket in the cloud, a container storage volume, or even a blockchain. Given this diversity of data storage techniques, relying on data-level encryption alone makes less sense. You need a way to encrypt data no matter how or where it is stored.
  • Open source security risks: Bugs like Heartbleed have highlighted vulnerabilities in the open source libraries that are typically used for transport-layer encryption. While these libraries are still viable, teams have recognized that it’s beneficial to implement additional layers of encryption in case the open source tools they use turn out to be flawed.

Security Benefits of Application-Level Encryption

Encrypting data at the application level provides a variety of benefits that help to address these challenges.

Infrastructure- and Architecture-Agnostic Encryption

When you encrypt data at the application level, it doesn’t matter how your overall application stack is designed or where it’s hosted. Whether you’re running an app in containers on Kubernetes, on-prem, or in the cloud, or whether you store data using a conventional file system, cloud object storage, storage volumes, or another technique, app-level encryption will protect your data.

Encrypt Data Without “Trusting” Infrastructure

Application-level encryption secures data even if you can’t trust your infrastructure to do the same. You may not have total control over who can access the servers and storage media that your application uses, especially if you use the cloud or another type of shared hosting environment. With app-level encryption, this doesn’t matter, because you are not relying on infrastructure-level security controls.

Guard Against Open Source Vulnerabilities

Although you may choose to use open source encryption libraries to help implement application-level encryption, it typically won’t be as obvious to outsiders that you are using those libraries as it is if you use an open source transport-layer encryption protocol. Only your development team will know how your application implements encryption internally. In this respect, app-level encryption can mitigate some of the risks associated with the exploitation of known vulnerabilities in open source encryption libraries.

More Flexibility in Key Management

Building encryption into your application provides you with more control over how that encryption is implemented. In turn, it gives you more flexibility with regard to how you manage encryption keys.

If you encrypt data at the database or network level, the encryption keys typically need to be stored somewhere that is external to your applications – which is riskier because it makes it easier for unauthorized users to access it. With encryption built into the app, however, you can manage keys via external application logic as well, providing another layer of protection.

Granular Access Control

Last but not least, one of the most powerful benefits of application-level encryption is that it makes it easier to implement highly granular controls over which applications and users can access which data.

With traditional encryption approaches, all data that passes through a network or is stored in a certain place on your infrastructure is typically secured in the same way. As a result, any application or user with an encryption key for that data can access the data. It’s hard to give only certain users or apps access to certain data, especially if access requirements change continuously (which would require updating and redistributing keys).

With app-level encryption, however, each application can encrypt data in its own way. It can also use Role-Based Access Control (RBAC) systems to determine which users should be able to access which data, and decrypt it accordingly.

Application-Level Encryption Is an Essential Component of Modern Encryption

None of the above means that application-level encryption is a replacement for or alternative to other forms of encryption. In many cases, teams should also use infrastructure-level and transport-layer encryption alongside application-level encryption.

However, application-level encryption solves certain data security and protection challenges that other types of encryption don’t address – at least not as efficiently or flexibly. That’s especially true for teams that deliver complex, distributed applications running on cloud-native infrastructure. For any business modernizing its software stack, investing in application-level security is a wise choice.