A proof-of-concept cracker for cryptocurrency brainwallets and other low entropy key algorithms.
⚠️ I am not currently maintaining Brainflayer. It has acomplished what I set out to do with it, and the work that went into it brought about a major inflection point in my career, but I have moved on to other things. Someday, I may come back to it, but don’t count on that. ⚠️
I am currently suing the British Government. If you’ve found my work useful…
…please donate to my crowdfunding effort.
Brainflayer is a Proof-of-Concept brainwallet cracking tool that uses
libsecp256k1 for pubkey generation.
It was originally released as part of my DEFCON talk about cracking brainwallets
(slides, video, why).
The name is a reference to Mind Flayers,
a race of monsters from the Dungeons & Dragons role-playing game. They eat
brains, psionically enslave people and look like lovecraftian horrors.
The current release is more than four times faster than the DEFCON release, and
many features have been added.
If brainflayer is useful to you, please get in touch to let me know. I’m very
interested in any research it’s being used for, and I’m generally happy to
collaborate with academic groups.
Just because you can steal someone’s money doesn’t mean you should.
Stealing would make you a jerk. Don’t be a jerk.
No support will be provided at this time, and I may ignore or close issues
requesting support without responding.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS”
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
Precompute the bloom filter:
hex2blf example.hex example.blf
Run Brainflayer against it:
brainflayer -v -b example.blf -i phraselist.txt
or
your_generator | brainflayer -v -b example.blf
Brainflayer’s design is heavily influenced by Unix philosophy.
It (mostly) does one thing: hunt for tasty brainwallets. A major feature it
does not have is generating candidate passwords/passphrases. There are plenty
of other great tools that do that, and brainflayer is happy to have you pipe
their output to it.
Unfortunately, brainflayer is not currently multithreaded. If you want to have
it keep multiple cores busy, you’ll have to come up with a way to distribute
the work yourself (brainflayer’s -n and -k options may help). In my testing,
brainflayer benefits significantly from hyperthreading, so you may want to
run two copies per physical core. Also worth noting is that brainflayer mmaps
its data files in shared memory, so additional brainflayer processes do not
use up that much additional RAM.
While not strictly required, it is highly recommended to use the following
options:
-m FILE Load the ecmult table from FILE (generated with ecmtabgen)
rather than computing it on startup. This will allow multiple
brainflayer processes to share the same table in memory, and
signifigantly reduce startup time when using a large table.
-f FILE Verify check bloom filter matches against FILE, a list of all
hash160s generated with
sort -u example.hex | xxd -r -p > example.bin
Enough addresses exist on the Bitcoin network to cause false
positives in the bloom filter, this option will suppress them.
Brainflayer supports a few other types of input via the -t option:
-t keccak passphrases to be hashed with keccak256 (some ethereum tools)
-t priv raw private keys - this can be used to support arbitrary
deterministic wallet schemes via an external program. Any trailing
data after the hex encoded private key will be included in
brainflayer’s output as well, for reference. See also the -I
option if you want to crack a bunch of sequential keys, which has
special speed optimizations.
-t warp salts or passwords/passphrases for WarpWallet
-t bwio salts or passwords/passphrases for brainwallet.io
-t bv2 salts or passwords/passphrases for brainv2 - this one is very slow
on CPU, however the parameter choices make it a great target for GPUs
and FPGAs.
-t rush passwords for password-protected rushwallets - pass the fragment (the
part of the url after the #) using -r. Almost all wrong passwords
will be rejected even without a bloom filter.
Address types can be specified with the -c option:
-c u uncompressed addresses
-c c compressed addresses
-c e ethereum addresses
-c x most signifigant bits of public point’s x coordinate
It’s possible to combine two or more of these, e.g. the default is -c uc.
An incremental private key brute force mode is available for fans of
directory.io, try
brainflayer -v -I 0000000000000000000000000000000000000000000000000000000000000001 -b example.blf
See the output of brainflayer -h for more detailed usage info.
Also included is blfchk - you can pipe it hex encoded hash160 to check a
bloom filter file for. It’s very fast - it can easily check millions of
hash160s per second. Not entirely sure what this is good for but I’m sure
you’ll come up with something.
Should compile on Linux with make provided you have the required devel libs
installed (at least openssl and gmp are required along with libsecp256k1’s
build dependencies). I really need to learn autotools. If you file an issue
about a build failure in libsecp256k1 I will close it.
Dependencies should install with
apt install build-essential libgmp-dev libssl-dev
Supported build target is currently Ubuntu 20.04 on amd64/x86_64. Issues with
building for other platforms probably won’t be fixed. In particular, Kali Linux
is not supported. Support for operating systems other than Linux would require
extensive refactoring of Brainflayer’s memory optimizations and is not happening.
Redistribution of compiled brainflayer binaries is prohibited, and
unauthorized binaries probably contain malware.
The bulk of Brainflayer was written by Ryan Castellucci. Nicolas Courtois and
Guangyan Song contributed the code in ec_pubkey_fast.c which more than
doubles the speed of public key computations compared with the stock secp256k1
library from Bitcoin. This code uses a much larger table for ec multiplication
and optimized routines for ec addition and doubling.