MS Defends Windows 10 Policy to Copy Hard Drive Keys

Microsoft has confirmed it automatically uploads Windows 10 disk encryption keys to its servers. The company says it was a deliberate decision based on weighing up the worst case scenarios.

The encryption key in question is not related to logging into and running Windows itself. Instead its an encryption of the entire hard drive of the device running Windows 10. This means that if somebody physically steals your computer, they can't make any sense of the data, even if it's been copied to another device (using a disk image backup, for example).

Encryption Key Would Help Computer Thieves

The encryption system Microsoft uses includes a recovery key: literally a string of characters which allow access to the files in decrypted form. For users of the Pro and Enterprise editions of Windows 10, there's an option to store the key in a place of your choice, such as on an external hard drive or USB stick, or simply to print it out for future reference.

However, on the ordinary Home edition of Windows 10, the key is automatically uploaded to Microsoft's servers, where it can be accessed via the user's Microsoft log-in. It's possible to delete the key but not to stop it being uploaded to begin with. It's worth noting that the encryption system cannot be enabled unless Windows 10 Pro or higher is running on the system. So, Home users would need to upgrade to Pro to enable the encryption.

In theory at least, having the keys stored on Microsoft's servers could be a security risk if somebody was able to gain physical access to a computer and find the associated encryption key. This could happen if the wrongdoer was able to get hold of the user's Microsoft log-in and access their account. Alternatively, it's possible - though highly unlikely - that Microsoft's server could be compromised, exposing encryption keys in bulk.

Microsoft Defends Automatic Upload

The chances are this is more likely to be a problem for specific targeted attacks on individuals, such as those who deal with particularly sensitive information. Microsoft says it chose this set-up to avoid the problem of a user's computer getting stuck in recover mode and them neither remembering nor being able to get hold of their encryption key. In this case the content of the computer would effectively be lost for good unless backed up.

However, security experts aren't convinced. A professor of cryptography told The Intercept that having encryption keys automatically stored on Microsoft servers "fundamentally changes the security properties of a disk encryption system." (Source: theintercept.com)

Meanwhile Business Insider notes that in some judicial systems, governments may be able to demand a third party such as Microsoft hand over the encryption key, thus allowing officials to access a seized drive without the user's permission. (Source: businessinsider.com)

What's Your Opinion?

Were you aware of the encryption settings in Windows 10? Should Microsoft upload the keys automatically or make it an opt-in system? Is it right to argue that the practical benefits to users outweigh any security concerns?