STANFORD UNIVERSITY INFORMATION TECHNOLOGY SERVICES Windows Encryption File System (EFS) Tech...

STANFORD UNIVERSITY • INFORMATION TECHNOLOGY SERVICES

Windows Encryption File System (EFS)

Tech BriefingJuly 18th 2008

http://www.stanford.edu/services/efs


04/19/23 Windows Encrypting File System (EFS) page 2

Agenda

Stanford Users• What is EFS

• What does it Protect• Is this for me? • Features• Data Recovery Agent• Getting Started

• Demo - How to Encrypt• Demo – How to backup Key

IT Support Staff• How to setup Data Recovery Agent


What is Encrypting File System (EFS)

The Microsoft Windows Encrypting File System (EFS) is feature built into the file system of the Windows XP and Windows Vista operating systems. It lets you encrypt designated files on a local computer so that no other user can access your data. When a file is encrypted, EFS automatically decrypts the file for use and re-encrypts the file when it is saved.

EFS is particularly useful for protecting data on a computer that might be physically stolen, such as a laptop.



What It Protects

EFS protects files you designated if your computer is lost or stolen.

If someone tries to break in or has access into your system to retrieve files, they will not be able to open the file even if they can see that it exists (as long as they do not have your SUNet ID and password).

Files copied to a Web folder using WebDAV are kept encrypted.



What It Doesn’t Protect or Prevent

It does NOT provide encryption to files that are:• Sent via email• Kept on a separate flash drive/thumb drive/USB

drive/floppy disk • Moved over the network via shared folders (CIFS/AFS)• System and page file• Compress Files• Files moved into folder set to encrypt all files• Files form being deleted

When you are about to move an encrypted file, Windows will warn you that you will lose your EFS encryption. Keep in mind that whenever you move a file off of your computer, it is probably no longer protected by EFS.



Is this for me?

Reasons for using EFS• Want to secure files on your computer incase it is stolen or

lost• You work with or store restricted data on your local computer• You travel and need to work with restricted data

Requirements• Windows XP Professional• Windows Vista Business, Enterprise or Ultimate• Computer is a member if University Windows Infrastructure

(AD)• Users is logged on to the computer with their SUNet ID (WIN

Domain), local computer or child domain accounts will NOT work

• Hard drive is formatted with NTFS



Features

Microsoft Windows Encrypting File System (EFS)• Transparent encryption done at the file-system level • If a folder is marked, every file created or moved into it will

be encrypted• File encryption keys can be archived (USB Flash Drive, File

server)• There is no “back door” • Keys are protected with the users password on the computer• Data Recovery Agent to allow for recovery of files if user’s

key is lost

Future Features Additional Users can be added to a file Group Policy to Auto Encrypt “My Documents” Folder



Data Recovery Options

Once a file is encrypted only the users private key can access the file. Should this key get lost the data will be inaccessible. Options to protect the data include:

User copies key to USB flash drive and store separately from computer

Configure Data Recover Agent (DRA)• Domain Wide DRA• Local/Departmental DRA



Data Recovery Agent (DRA)

These data recovery agents (DRAs) are a separate set of issued recovery certificates with public and private keys that can be used to recover files.

Recommendation for DRAs• Local Systems Administrators• Separate flash drive (Iron Key) stored in secure location

(safe)

Requirements for Recovery• Admin will need read access to files at time of recovery• Password for the DRA Private Key



Getting Starting For End Users

Open a HelpSU Request

Once you have approval from your Local Support Staff that they have setup the DRA you can then choose directories to start encrypting.

Copy your Key to a External USB Drive



Demo 1

How To Encrypt Files



Demo 2

How to back-up Your Keys



Storing User Keys

Export and then Delete Key on local computer

External USB Flash Drive• NOT stored with your computer or in laptop bag• Encrypted (optional)What



Known Issues

DCOM Required1. Start Registry Editor. 2. Locate the following path:

HKEY_LOCAL_MACHINE\Software\Microsoft\OLE

3. Change the EnableDCOM string value to Y. 4. Restart the operating system for the changes to take

effect.

Note: There is a BigFix fixlet to re-enable DCOM

Vista and Symantec Bug – Patch available on ESS



Demo 3

How to Setup DRA



Questions and Answers

Extra Info for users and admins• Stanford Data Classification

http://www.stanford.edu/group/security/securecomputing/dataclass_chart.html

• Windows Desktop File Encryption and EFS


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