How to lock a folder on a USB drive?

Question

I have a requirement to implement a feature (in C#) to lock a folder on a USB drive. After locking, in any PC without my software, this folder is inaccessible (or better inv

Answer 1

Have you had a look at TrueCrypt?

In general you shouldn't try to reinvent the wheel, especially with security requirements. This is a heavy topic and messing around with the file system on your own should be the last option to consider.

TrueCrypt uses two different modes of operation:

• File-hosted (container)
• Partition/device-hosted

Note: In addition to creating the above types of virtual volumes, TrueCrypt can encrypt a physical partition/drive where Windows is installed (for more information, see the chapter System Encryption).

A TrueCrypt file-hosted volume is a normal file, which can reside on any type of storage device. It contains (hosts) a completely independent encrypted virtual disk device.

A TrueCrypt partition is a hard disk partition encrypted using TrueCrypt. You can also encrypt entire hard disks, USB hard disks, USB memory sticks, and other types of storage devices.

Answer 2

I have used this software before, which is open source, so you might get something out of it. http://www.truecrypt.org/

However, I think it works at the partition level rather than the drive level (I think it formats the partition using its own file system).

Answer 3

For the data to be inaccessible, you would need to create an encrypted container which your program would represent as a virtual folder on existing disk or a virtual disk (drive letter). The first is possible with Pismo File Mount, the second - with our product (Solid File System OS edition). Both approaches require installation of the kernel-mode driver to the system. This is not an application requirement but OS architecture requirement.

From technical point of view our approach is more robust because Pismo File Mount uses a filter driver, while SolFS uses a file system driver and filter drivers are more complicated and more prone to compatibility issues (we have filter-based product as well, so I have experience with both approaches).

(Note: TrueCrypt has nothing to do with C#. So that isn't applicable here.)