2.4.1 Encrypting File System (EFS)
Windows Server 2003 supports Encrypting File System (EFS) which allows users to encrypt their files and
folders. In Windows Server 2003, users can encrypt files and folders on the local computer and across the
network. In addition, users can also encrypt offline files. However, EFS is only supported on NTFS volumes.
When a user encrypts a file, only that user will be able to use the file. They can use the encrypted file
without having to decrypt the file first. EFS can be implemented from Windows Explorer or from the
command prompt using the Cipher command. The syntax for the cipher command is:
cipher [/e | /d] [/s:folder_name] [/a] [/i] [/f] [/q] [/h] [/k] [file_name [...]]
For a list of Cipher command switches see Table 2.1.
EFS is only supported on NTFS version 5
Compressed files cannot be encrypted using EFS
System files cannot be encrypted
Encrypted files cannot be shared
Encrypted flies or folders that are moved or copied to partitions or volumes that are not formatted with
the NTFS file system will become decrypted
Files and folders on network computers can be encrypted if you have the necessary access permissions
to the network computer’s NTFS volume and if file encryption is enabled on the network computer.
TABLE 2.1: Command-line Switches for the Cipher Command
Encrypts the specified folders and marks them so that files that are
added later will be encrypted.
Decrypts the specified folders. Files that are added to the folder will no
longer be encrypted.
Performs the specified operation on folders in the given folder and all
Performs the specified operation on files and folders.
Continues performing the specified operation even after errors have
Forces the encryption operation on all specified files, even those that
are already encrypted.
Reports only the most essential information.
Displays files with the hidden or system attributes.
Creates a new file encryption key.
Specifies a pattern, file, or folder.
Windows 2003 also supports encryption of offline files. This enables users to use offline file storage while
retaining the ability to protect their files with encryption.