Nowadays more and more people inclined to backup their documents to cloud such as Dropbox, CloudLayer Storage of softlayer, Google docs, Windows Live SkyDrive, Box.net, virtual private servers, etc.
Although your data is encrypted on the server side, it’s not guaranteed to be 100% secure, the employers of the corporation or hackers could grab your password and subsequently download your files to his own computer.
You can encrypt your files and folders on local hard drive with TrueCrypt, but the file container of the virtual volume created with TrueCrypt is usually very large, thus it’s not suitable for online delivery( However, if you own a VPS server, it’s a good idea to encrypt your files with TrueCrypt and upload it to your own server, because it offers you the ability to verify the integrity of it by computing and comparing the MD5 checksum value of the original file and the backup file easily with the md5sum command in Linux and free MD5 checkers for Windows. ).
Imagine that you are a Dropbox user, it’s a better solution to encrypt the files on your local computer individually before uploading them to Dropbox. You can achieve the effect with SecretSync or Boxcryptor, but they are not ideal.
All we need is an offline software which is capable of monitoring or watching a specific folder for file/folder creation or overwriting, when a change is detected, it will encrypt and copy the modified file to the correspondence directory, in a short word, it’s a utility for folder backup and synchronization in real time with support for encryption, however, to my sadness, most of them are not free.
But Cobian Backup Boletus may help you, it’s a free folder backup and sync software which supports encryption and scheduled tasks, you can set its schedule type to “Timer” and turn on the encryption, once you’ve installed it and set up a task, it’s will encrypt and copy the changed/added files to your specified folder regularly, you can set the destination folder to your Dropbox folder, then all files will be encrypted before they are uploaded to Dropbox.
Cobian Backup Boletus has an embedded decryption tool which allows you to decrypt the encrypted files with ease.
Cobian Backup Boletus supports most common Windows OSes.
Cobian Backup Boletus is a 14.77MB download available from CNET.