Multiparty computation with SPDZ online phase and MASCOT offline phase
C++ Python Other

(C) 2016 University of Bristol. See License.txt

Software for the SPDZ and MASCOT secure multi-party computation protocols. See Programs/Source/ for some example MPC programs, and for a basic tutorial. More examples and documentation will be available in the coming weeks.

See also


  • GCC
  • MPIR library, compiled with C++ support (use flag --enable-cxx when running configure)
  • CPU supporting AES-NI and PCLMUL
  • Python 2.x, ideally with gmpy package (for testing)


  • g++ might actually refer to clang, in which case you need to change CONFIG to use GCC instead.
  • It has been reported that MPIR has to be compiled with GCC for the linking to work: ./configure CC=<path to GCC gcc> CXX=<path to GCC g++> --enable-cxx

To compile SPDZ:

1) Optionally, edit CONFIG and CONFIG.mine so that the following variables point to the right locations:

  • PREP_DIR: this should be a local, unversioned directory to store preprocessing data (defaults to Player-Data in the working directory)

2) Run make (use the flag -j for faster compilation with multiple threads)

To setup for the online phase



This sets up parameters for the online phase for 2 parties with a 128-bit prime field and 40-bit binary field, and creates fake offline data (multiplication triples etc.) for these parameters.

Parameters can be customised by running

Scripts/ <nparties> <nbitsp> <nbits2>

To compile a program

To compile the program in ./Programs/Source/tutorial.mpc, run:

./ tutorial

This creates the bytecode and schedule files in Programs/Bytecode/ and Programs/Schedules/

To run a program

To run the above program (on one machine), first run:

./Server.x 2 5000 &

(or replace 5000 with your desired port number)

Then run both parties' online phase:

./Player-Online.x -pn 5000 0 tutorial

./Player-Online.x -pn 5000 1 tutorial (in a separate terminal)

Or, you can use a script to do the above automatically:

Scripts/ tutorial

To run a program on two different machines, firstly the preprocessing data must be copied across to the second machine (or shared using sshfs), and secondly, Player-Online.x needs to be passed the machine where Server.x is running. e.g. if this machine is name diffie on the local network:

./Player-Online.x -pn 5000 -h diffie 0 tutorial

./Player-Online.x -pn 5000 -h diffie 1 tutorial

Compiling and running programs from external directories

Programs can also be edited, compiled and run from any directory with the above basic structure. So for a source file in ./Programs/Source/, all SPDZ scripts must be run from ./. The script must also be run from ./ to create the relevant data. For example:

spdz$ cd ../
$ mkdir myprogs
$ cd myprogs
$ mkdir -p Programs/Source
$ vi Programs/Source/test.mpc
$ ../spdz/ test.mpc
$ ls Programs/
Bytecode  Public-Input  Schedules  Source
$ ../spdz/Scripts/
$ ls
Player-Data Programs
$ ../spdz/Scripts/ test

Offline phase (MASCOT)

In order to compile the MASCOT code, the following must be set in CONFIG or CONFIG.mine:


It also requires SimpleOT:

git submodule update --init SimpleOT
cd SimpleOT

If SPDZ has been built before, any compiled code needs to be removed:

make clean

HOSTS must contain the hostnames or IPs of the players, see HOSTS.example for an example.

Then, MASCOT can be run as follows:

host1:$ ./ot-offline.x -p 0 -c

host2:$ ./ot-offline.x -p 1 -c