I recently wrote about how to protect important folders using new features in the OneDrive sync client. That story prompted an email from one of our readers who asked me about the encryption of OneDrive files. There are two answers depending on your version of OneDrive.
If you are a consumer OneDrive user, i.e. you have the free version of OneDrive and Office 365 Personal and Home subscribers, then your OneDrive files are only encrypted as they move between your system and Microsoft’s data center. They are also encrypted if that storage is moved between their data centers. In other words, anytime those files you place on OneDrive are transmitted or received, they are encrypted.
This encryption occurs whether you are sending and receiving OneDrive files through your web browser, the sync client or the mobile OneDrive apps on iOS and Android. Once that file is stored in one of Microsoft’s data centers it is not encrypted any further. This is commonly referred to as data being encrypted at rest.
If you are a commercial Office 365 customer, then your OneDrive data is also encrypted during its transit to and from your devices like it is for consumers. However, commercial subscribers also get the added benefit of their data being encrypted at rest as it resides on Microsoft’s data center storage servers.
No action is required on your part for any of this encryption to happen – it is part of the overall OneDrive system/processes.