DriveHQ Encrypted Folder feature is very secure. Your files are encrypted locally using your own encryption key, which is never sent to DriveHQ server. Your files will remain encrypted on DriveHQ server. Without your encryption key, even DriveHQ support team cannot decrypt your files.
Sharing of encrypted folders is more complicated than sharing regular folders. You could use the encrypted folder feature, share to other people and provide the encryption key to them. The challenging part is: you will give the other people your encryption key. This may not be suitable in many cases.
Using DriveHQ Group Account, you can more easily solve the problem. In stead of providing your own encryption key, you can create a sub-user account for sharing files between you and your client. Both you and your client can logon as the same sub-user. You can then set an encryption key for the sub-user's encrypted folder; and give the same encryption to your client.
All files uploaded to the encrypted folder:
\My Documents\My Encrypted Data
are automatically encrypted locally and keep encrypted on server. So you must use DriveHQ FileManager (or DriveHQ Online Backup) to download them. When you download an encrypted file using DriveHQ client software, the file is automatically decrypted locally. (It will prompt you for the encryption key during the first download, if download from a different PC).
If you need to share ultimate secure documents with more people, then you can create a sub-user account for each client. Different users can use different encryption key.
Dependent on your needs, you might use the same sub-user account for multiple clients; or you can delete / edit a sub-user account after you have finished sharing secure files.