In Mid-2014 Microsoft introduced a new encryption technology to Office 365 that they code named “Fort Knox”. Fort Knox is a blob encryption technology that is applied to SharePoint Online and OneDrive for Business, and as I am primarily an Exchange guy I was not really aware of Fort Knox until recently. After taking a look at this technology, I think it is a pretty nifty bit of security that Office 365 customers, and potential Office 365 customers, should know about.
The technical details of what Fort Knox does are pretty cool. The first thing this process does is split the file stored in SharePoint Online or OneDrive for Business into parts. These different parts of the file are then stored in different containers within the service. This first level of security means that if, for some reason, Office 365 is compromised and bad guys get into some data, what they will end up with is a bunch of file fragments that are of no use.
The next level of protection is that each of these file fragments is encrypted with a different key. This means that even is a bad guy does get into multiple Office 365 storage containers to retrieve entire files, each part of the files are encrypted with different keys. Additionally the file map that tells SharePoint how to assemble these file fragments is also encrypted with its own key.
All of this encryption with separate keys can have the potential to cause problems. The way Microsoft avoids those problems is by using one master key to encrypt all these separate keys. This master key is stored in a separate key store from all the individual keys. All-in-all it seems to be that this Fort Knox encryption system is pretty darn secure.
The one area where this security falls down is in the case of government access. The United States and several other governments are involved in cases with Microsoft and other tech companies demanding various levels of access to customer data stored on cloud services. By and large Microsoft seems to be doing a good job of opposing this sort of government demand, by we can never be completely sure of what is going on behind the scenes. If governments are going forces Microsoft to give up your data without notifying you, then your only protection is going to be to physically control your data yourself.