Open Bitlocker USB stick on OS X

Actually I asked after some success because I thought it would benefit everyone ;-)

Here is the complete process. Some links are missing because I don't have enough reputation to embed them all. Sorry about that.

High-level, we "just" need dislocker.

But to install it, there are some dependencies to resolve... we need:

"Fuse for OS X"
- Simply download the .img on their site, open and run the .pkg installer
Xcode command-line developers tools
- I'm not sure what's the generic answer.
- Open a terminal, and type
```
xcode-select --install
```
  - If you get an error "-bash: xcode-select: command not found", you need to install Xcode from the App store, then start again this command.
  - If an alert windows popup asking if you want to install, click on "install" button.
  - If it prints error "xcode-select: error: command line tools are already installed, [...]", you're all set.
"Homebrew"
- Following instruction on their website, type following in terminal:
```
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
```
- If you get an error about Xcode tools not being installed whereas you did install it, then change the path to Xcode:
```
sudo xcode-select -switch /
```
and obviously dislocker !
- Download ZIP (available in green button "Clone or Download" on the right)
- Extract ZIP content
- Open terminal and change directory to the dislocker-master directory
- Compile and install dislocker:
```
brew install src/dislocker.rb
```
  - If you get an error about Xcode tools not being installed whereas you did install it, then change the path like this:
```
sudo xcode-select -switch /
```

Don't be desperate, it's now time to mount the USB stick !

But it's not gonna be trivial...

Identify the device of the USB stick, using Disk Utility:
- Open Disk Utility and select the USB stick drive. Somewhere you should get something like "disk3s1". Replace this example with your actual value in following lines.
- Keep Disk Utility open, it will be used in next steps
Eject the USB drive for example from Disk Utility (Unmount button)
Create a directory for the decrypted file
```
sudo mkdir /tmp/mydrive
```
Warning: this directory will have strange characteristics: it appears with "ls" but not with "ls -l" and not in the Finder wherever it is, moreover the content can't be listed, and trying to delete it often fails with strange error messages. That's why I put it in /tmp which is cleaned at every reboot.
Decrypt the USB stick with dislocker. If disk is "disk3s1" and the password is "MyPassword", the command will look like:
```
sudo dislocker-file -V /dev/disk3s1 -v -uMyPassword -r -- /tmp/mydrive
```
Add the disk image to Disk Utility and mount it
```
sudo hdiutil attach -imagekey diskimage-class=CRawDiskImage /tmp/mydrive/dislocker-file
```
Note: Don't try to list "/tmp/mydrive/dislocker-file" by yourself. Just assume it is there and write the path as is.

Hourray !!!, the new drive is there !

Because really nothing is easy, to clean-up you need to do the following:

Unmount the drive
- For example from your friend Disk Utility, select its icon and click on "Unmount" button
Get rid of the image
- From "Disk Utility", select the greyed drive, and from the menu "File" select "Eject".
Detach the fuse volume
```
sudo  hdiutil detach /tmp/mydrive/
```

Only now the directory /tmp/mydrive is a plain directory that can be deleted...

As you noticed the process is definitely complex and finally I just get a read-only drive. I'm interested by any better answer.

I'd like to share my experience on High Sierra, as it seems to be even simpler.

Installation

Homebrew

/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

Fuse for macOS

brew cask install osxfuse

Notes

To install and/or use osxfuse you may need to enable their kernel extension in System Preferences → Security & Privacy → General
Make sure to reboot before proceeding further (as osxfuse advises to do so).

dislocker

brew install dislocker

Operation

Mount

# to unlock the dislocker image
sudo dislocker -v -V /dev/disk3s1 -r -uPASSWORD ~/mydrive

# to mount the unlocked image
sudo hdiutil attach /tmp/mydrive/dislocker-file -imagekey diskimage-class=CRawDiskImage -mountpoint /Volumes/mydrive

Unmount

# unmount the unlocked image
sudo hdiutil detach /Volumes/mydrive

# release the unlocked bitlocker
sudo hdiutil detach /tmp/mydrive

Script

I've also created a gist to ease the mount/unmount procedure:

# mount, will be available at /Volumes/bitlocker.disk3s1
sudo mount-bitlocker /dev/disk3s1 PASSWORD

# unmount
sudo umount-bitlocker /dev/disk3s1