Is Encryption The Solution To Cloud Computing Security And Privacy?

Encrypt your data after storing it in the cloud.

By Erik J. Heels

First published 8/4/2011; CloudSwitch Blog; publisher: CloudSwitch

Wikipedia defines “cloud computing” as “the logical computational resources (data, software) accessible via a computer network (through WAN or Internet etc.), rather than from a local computer. Managing local computers is hard: there are security issues, computer lifecycle issues, accessibility issues. Cloud computing, ideally, is easy: set it and forget it, access your data from anywhere, outsource your IT headaches to your service provider. To end users, whether individuals or companies, “the cloud” is an abstraction, a computing environment that can expand to suit users’ needs.

What’s The Problem?

One problem with cloud computing is that both cloud computing providers and law enforcement agencies can access your files, usually more easily than if your stored the files on your own computer.

Also, security breaches, like the much-publicized Dropbox security breach, during which all Dropbox accounts were accessible to all users without any password protection, can occur in the cloud.

For users, it is important to know whether your data is secure, who can access it, and what happens when there is a security breach.

For service providers, it is important to comply with both US and non-US laws including (1) data retention laws, which are ostensibly designed to help law enforcement entities do their job and (2) data disclosure laws, which are ostensibly deigned to help users know when their private information has been compromised.

Is Encryption The Answer?

Most cloud computing providers (1) authenticate (e.g. transfer usernames and password) via secure connections and (2) transfer (e.g. via HTTPS) data securely to/from their servers (so-called “data on the wire”), but, as far as I can tell, none (3) encrypts stored data (so-called “data at rest”) automatically.

So if you want your data to be secure in the cloud, then consider encrypting the stored data. And don’t store your encryption keys on the same server! It is unclear whether a cloud computing provider could be compelled by law enforcement agencies to decrypt data that (1) it has encrypted or that (2) users have encrypted, but if the provider has the keys, decryption is at least possible.

I have used and abandoned both Microsoft’s Encrypting File System (EFS) and Apple’s FileVault for encrypting data on my desktop computers. But desktop encryption is painfully slow!

Perhaps cloud computing providers can leverage the power of their data centers to make the performance hit of encryption-decryption imperceptible to the user. That would be cool. And would make the benefits of cloud computing greatly outweigh the risks.

Here are three security questions you should ask of your cloud computing provider:

  1. Data On The Wire. Are files transferred to/from cloud servers encrypted by default?
  2. Data At Rest. Are files stored on cloud servers encrypted by default?
  3. Data Retention. If files on cloud servers are encrypted and there is a request from law enforcement to decrypt the data, then what do you do? Bonus question: What if you have the key(s)?

I searched for answers to these questions for four cloud computing providers (sourced in part from TechTarget’s list of top cloud computing providers and Wikipedia’s list of cloud computing providers) that are popular with small businesses like mine:

Simple Google searches of these providers’ websites provided more questions than answers on the topic of encryption:

Cloud service providers need to do a much better job of communicating what is and what is not secure about their offerings. For example, I would characterize Dropbox’s security page as misleading at best.

“Your files are actually safer while stored in your Dropbox than on your computer in some cases. We use the same secure methods as banks and the military…. Like most online services, we have a small number of employees who must be able to access user data for the reasons stated in our privacy policy (e.g., when legally required to do so). But that’s the rare exception, not the rule.”

Just because your files are transferred securely to Dropbox does not mean they are stored in an encrypted format on Dropbox’s servers. And it is the “rare exception” that is, or should be, the concern of users.

For More Information


As more individuals and companies move their computer files and computer applications from local client computers (over which they have a great deal of control) to remote server computers (over which they have limited control), security becomes a bigger concern – both for users and for service providers.

Erik J. Heels is an MIT engineer; trademark, domain name, and patent lawyer; Red Sox fan; and music lover. He blogs about technology, law, baseball, and rock ‘n’ roll at His law firm, Clock Tower Law Group represents cool companies such as CloudSwitch

One Reply to “Is Encryption The Solution To Cloud Computing Security And Privacy?”

Leave a Reply

Your email address will not be published. Required fields are marked *