Cryptography and Encryption

BitCracker – Open Source BitLocker Password Cracking Tool

BitCracker is the first open source BitLocker password cracking tool. BitLocker is a full-disk encryption feature available in recent Windows versions (Vista, 7, 8.1 and 10) Pro and Enterprise. BitCracker is a mono-GPU password cracking tool for memory units encrypted with the password authentication mode of BitLocker (see picture below).



Our attack has been tested on several memory units encrypted with BitLocker running on Windows 7, Window 8.1 and Windows 10 (both compatible and non-compatible mode). Here we present two implementations: CUDA and OpenCL.



For CUDA implementation, you need at least CUDA 7.5 and an NVIDIA GPU with minimum cc3.5 (i.e. Kepler arch)


How To

Use the script to build 3 executables:

  • hash extractor
  • BitCracker CUDA version
  • BitCracker OpenCL version


The executables are stored in the build directory. Before starting the attack, you need to run bitcracker_hash to extract the hash from the encrypted memory unit.

> ./build/bitcracker_hash -h

Usage: ./build/bitcracker_hash -i <Encrypted memory unit> -o <output file>


  -h, --help		Show this help
  -i, --image		Path of memory unit encrypted with BitLocker
  -o, --outfile		Output file

The extracted hash is fully compatible with the John The Ripper format.

Then you can use the output hash file to run the BitCracker attack.

> ./build/bitcracker_cuda -h

Usage: ./build/bitcracker_cuda -f <hash_file> -d <dictionary_file>


  -h, --help		Show this help
  -f, --hashfile 	Path to your input hash file (HashExtractor output)
  -s, --strict		Strict check (use only in case of false positives)
  -d, --dictionary	Path to dictionary or alphabet file
  -g, --gpu 		GPU device number
  -t, --passthread	Set the number of password per thread threads
  -b, --blocks		Set the number of blocks

Note: In case of false positives you can use the -s option, that is a more restrictive check on the correctness of the final result. Altough this check is empirically verified and it works with the images of this repo encrypted with Windows 7, 8.1 and 10, we can’t guarantee that it doesn’t lead to false negatives. Use -s option only if BitCracker returns several false positives.

In the the script there are several attack examples using the encrypted images provided in this repo:

  • imgWin7: memory unit encrypted with BitLocker using Windows 7 Enteprise edition OS
  • imgWin8: memory unit encrypted with BitLocker using Windows 8 Enteprise edition OS
  • imgWin10Compatible.vhd: memory unit encrypted with BitLocker (compatible mode) using Windows 10 Enteprise edition OS,
  • imgWin10NonCompatible.vhd: memory unit encrypted with BitLocker (NON compatible mode) using Windows 10 Enteprise edition OS,
  • imgWin10CompatibleLong27.vhd: memory unit encrypted with BitLocker (compatible mode) using Windows 10 Enteprise edition OS using the longest possible password (27 characters)


Currently, BitCracker is able to evaluate passwords having length between 8 (minimum password length) and 27 characters (implementation reasons).

BitCracker doesn’t provide any mask attack, cache mechanism or smart dictionary creation; therefore you need to provide your own input dictionary.



Here we report best performance of BitCracker implementations tested on different GPUs

GPU Acronim GPU Arch CC # SM Clock CUDA
GFT GeForce Titan Kepler 3.5 14 835 7.0
GTK80 Tesla K80 Kepler 3.5 13 875 7.5
GFTX GeForce Titan X Maxwell 5.2 24 1001 7.5
GTP100 Telsa P100 Pascal 6.1 56 1328 8.0
AMDM Radedon Malta


Version GPU -t -b Passwords x kernel Passwords/sec Hash/sec
CUDA GFT 8 13 106.496 303 635 MH/s
CUDA GTK80 8 14 114.688 370 775 MH/s
CUDA GFTX 8 24 106.608 933 1.957 MH/s
CUDA GTP100 8 56 458.752 1.363 2.858 MH/s
OpenCL AMDM 32 64 524.288 241 505 MH/s
OpenCL GFTX 8 24 196.608 884 1.853 MH/s


John The Ripper

We released the OpenCL version as a plugin of the John The Ripper (bleeding jumbo) suite:

Download BitCracker

About the author

Mazen Elzanaty

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