Need help with hashclash?
Click the “chat” button below for chat support from the developer who created it, or find similar developers for support.

About the developer

266 Stars 52 Forks Other 85 Commits 3 Opened issues


Project HashClash - MD5 & SHA-1 cryptanalysis

Services available


Need anything else?

Contributors list

Project HashClash - MD5 & SHA-1 cryptanalytic toolbox

Feedback & pingback appreciated!


  • C++11 compiler (e.g. g++)
  • make
  • autoconf & automake & libtool

sudo apt-get install autoconf automake libtool
  • zlib & bzip2 libraries

sudo apt-get install zlib1g-dev libbz2-dev
  • Optional: CUDA

Building (automatic)

  • Run script


Building (manual)

See details

  • local boost C++ libraries (preferable version 1.57.0)


    Override default boost version 1.57.0 and/or installation directory as follows:

    BOOST_VERSION=1.65.1 BOOST_INSTALL_PREFIX=$HOME/boost/boost-1.65.1 ./

  • Build configure script

    autoreconf --install

  • Run configure (with boost installed in $(pwd)/boost-VERSION by

    ./configure --with-boost=$(pwd)/boost-1.57.0 [--without-cuda|--with-cuda=/usr/local/cuda-X.X]

  • Build programs

    make [-j 4]

Create your own chosen-prefix collisions

  • Create temporary working directory (in top directory)

mkdir cpc_workdir

cd cpc_workdir
  • Run script


Create you own identical-prefix collision

  • Create temporary working directory

mkdir ipc_workdir

cd ipc_workdir
  • Run script

echo -n "TEST" > prefix.txt

../scripts/ prefix.txt

Note: the prefix file is expected to be a multiple of 64 bytes and optionally plus a small multiple of 4 bytes. These last bytes will be used as forced message words in steps of 4 bytes inside the first near-collision block. Any remaining 1, 2 or 3 bytes of the prefix file are ignored.

Note: the first time the script is run it will be slower as it needs to create the 'upper' differential path set for the first time.

  • Example output:
$ xxd collision1.bin
0000000: 5445 5354 1789 6de2 c568 339d 8bbf 6269
0000010: 563a c4ab 2fba 7aba 6ec7 e182 8566 8883  V:../.z.n....f..
0000020: b0f2 d716 17d5 8f97 b244 b9ca dcaa af93  .........D......
0000030: 3a33 4552 a9fd 023b 7012 7e5c d644 9646  :3ER...;p.~\.D.F
0000040: 723e 737a 6c3a 66e5 5d51 8e7c 7bc2 ec4f  r>szl:f.]Q.|{..O
0000050: 95a2 349f 0f4b 2540 cbe6 5644 d113 104b  ..4..K%@..VD...K
0000060: 5c39 898d f19a f9e9 e2aa bbad e191 d2d3  \9..............
0000070: a25d 4df0 9058 a873 4ee8 9dc9 47a5 281c  .]M..X.sN...G.(.
  • Make your own attack

Inside there are three example identical-prefix collision attacks, selected by N=1, 2 or 3. You can add your own choice of message word differences here and see if you can make own collision attack!

We use cookies. If you continue to browse the site, you agree to the use of cookies. For more information on our use of cookies please see our Privacy Policy.