Problem description
The user is unable to access an encrypted file that was encrypted using inSync Data Loss Prevention feature.
Cause
The issue is caused when the EFS certificate gets updated on the user’s machine.
Validation
Create a new file and encrypt it. Follow the steps:
Right click on the newly created file and go to Properties.
At the bottom right click Advanced.
Select Encrypt contents to secure data.
Click Ok and Apply.
Once a test file is created follow the below steps on the newly created file and the one that does not open due to an Encryption error.
Right click on the file and go to Properties.
At the bottom right click Advanced.
On Advanced Attributes, click on Details.
You will see a Certificate Thumbprint.
Validate if the Certificate Thumbprint is the same or different for both the files.
If the Certificate Thumbprint is different, this may happen due to an EFS certificate update that can be caused due to many reasons, such as User’s Password Change, hostname change, re-imaged operating system.
Resolution
The issue can be resolved in two ways
Change the Default EFS Certificate:
Open Control Panel -> User Accounts -> Manage your file encryption certificates and click Next.
Click on Select certificates -> More options.
Select the correct certificate and click OK.
📝 Note
The above steps will only work if the selected certificate has a backup copy of your encryption key. If there is no backup of the encryption key, the encrypted file may be not accessible.
You can download these files from previous snapshots in inSync.