Using encrypted files and drives is normally something you can do without even thinking about it. In most cases, simply logging into your computer is all that is needed to access the data. However, in some cases you may need a special USB drive inserted into your computer before you log in. Of course, if the files or the encryption keys are lost or corrupted, getting in can be more difficult.
There are three ways to encrypt data on a Windows PC: using Windows' Encrypting File System (EFS), Windows' BitLocker, or by using a third-party software. Accessing the files will depend on which method was used to encrypt them.
How to Open Encrypted Files USING EFS
EFS comes with Windows 10 Pro, Enterprise, and Education editions. With EFS, you can encrypt individual files or folders. Encrypted files do not have a special file extension, but they do have a lock displayed on the icon.
To unlock these files, all you have to do is log into your computer using your password. If someone else logs into your computer, the files cannot be opened. EFS encryption keys are stored on your computer and are also encrypted. Someone with the know-how could eventually unlock those keys and gain access to the encrypted files.
How to Open Bitlocker-Encrypted Drives
Bitlocker is also available on Windows 10 Pro, Enterprise, and Education editions. Bitlocker encrypts the entire storage drive. Most computers using Bitlocker have a special chip built into the motherboard, called a Trusted Platform Module, or TPM. This chip stores parts of the encryption keys and if it detects someone is trying to get unauthorized access to the computer, it will lock them out.
The method of unlocking the drive to access its files depends on how Bitlocker was set up. In some cases, you simply have to enter your password to access the drive. In other cases, you will need to insert a pre-configured USB drive before turning on the computer. If the USB drive is not connected to the computer, you will be locked out.
How to Decrypt EFS Without a Certificate
Sometimes files and encryption keys can become corrupt due, for example, to a hard drive failure. It's also possible to lose access to an encrypted file because you have moved files or upgraded your computer.
If you have used EFS or a third-party software to encrypt a file, you may be able to unlock it using its file properties. Right-click the file in File Explorer, select Advanced and then clear the Encrypt Contents to Secure Data check box. If this does not work, contact the software provider.
Adding Users to an Encrypted File EFS Permissions List
Software developers or network engineers with knowledge of the C++ language can add additional users to an encrypted file's permission list. Microsoft has the sample code available that will add a new Data Recovery Field to the encrypted file using the AddUsersToEncryptedFile function. The new user must have had access to the file before in order for this to work, such as being someone who owned the file or made changes to it in the past.
How to Access Encrypted Files From Ransomware
Ransomware continues to be a serious threat for businesses, consumers and local governments. If your computer or computer network has been attacked, there's a strong possibility that you may never be able to get access to them again. There are, however, tools available from reputable companies that may be able to decrypt some or all of your files. The success of using these tools will depend on which version of malware has been used to attack your systems.
Of course, the best defense against ransomware is to practice good security habits:
- Make regular backups of your most important files and store them offline (disconnected from your computer or network) or store them with a cloud storage solution.
- Always install critical updates and patches to your operating system and software.
- Use reliable antivirus and anti-malware software and keep it up-to-date.
- Do not open email attachments or click links if you are uncertain of the contents.
