Using EFS with Offline Files

Windows 2000 introduced Encrypting File System (EFS) and Offline Files. EFS lets users encrypt files and folders on NTFS partitions. Offline Files lets users access files offline when their connection to the file server is interrupted. In Windows XP Professional, Microsoft has joined these technologies to enable administrators to encrypt offline files for added security. Let's take a look at how you can use this new capability to encrypt the offline file cache folder.

EFS 101
EFS lets users employ a combination of asymmetric and symmetric key cryptography to encrypt files. When a user first encrypts a particular file, Windows determines whether a Public Key Infrastructure (PKI) certificate server, such as Microsoft's Certificate Services provides, is available. If so, the PKI server will give the user a new EFS digital certificate with a 2-year life. If Windows can't detect a PKI server capable of distributing EFS certificates, Windows will generate a self-signed EFS certificate for the user with a life of 100 years. . . .