Readme.md

Privately Connecting Mobility to Infectious Diseases via Applied Cryptography

This repository contains the source code of the paper Privately Connecting Mobility to Infectious Diseases via Applied Cryptography. [1, 2]

Source code

The code is based on Microsoft SEAL (version 3.6.6) and is compatible with Windows and Linux. This repository contains a demo application (using random data) to perform the matrix multiplication on encrypted data, including the proving mask, noise flooding, and differential privacy. Use params.h for a parametrization of the code.

Compilation

Requirements

The source code just requires basic building tools (git, make, cmake) to compile. Use the following command to install these packages on Ubuntu:

sudo apt install git build-essential cmake

Compiling Instructions

Execute the compile.sh script (which contains the following commands) to compile the source code:

git submodule update --init --recursive
cd SEAL
mkdir build
cd build
cmake ..
make -j 6
cd ../..
mkdir build
cd build
cmake ..
make -j 6

The binaries can then be found in the bin folder:

Executable	Parameter	Description
main		Executes the whole protocol including the client and the server
client	enc	Creates keys, encrypts an input string, and stores everything on the file system
server		Takes ciphertexts and keys from the file system and executes the protocol
client	dec	Takes ciphertexts from the file system and decrypts the result of the protocol

Docker

One can use docker to compile and run the code. The following command creates a docker container with the compiled executables being present in the app folder:

docker build -t heatmap .

Use the following command to get a bash shell inside the app folder of the container, which contains all executables:

docker run -it heatmap

Binaries can then directly be executed from the current folder.

Benchmarks in the Paper

The benchmarks in the paper create a heatmap for 8 million subscribers and were thus executed on Amazon AWS using a EC2 instance with 96 vCPU's @ 3.6 GHz. To reproduce these benchmarks, modify the values in params.h to:

// matrix dimensions
constexpr uint64_t N = (1ULL << 23); // phone numbers
constexpr uint64_t k = (1ULL << 15); // cell sites

// Multithreading
constexpr uint64_t NUM_THREADS = 96;

Additionally, modify the following variables, if you want to use the 60-bit plaintext modulus instead of a 42-bit one:

// BFV parameters
constexpr uint64_t PLAIN_MODULUS = 1103311814658949121ULL;  // 60 bit
constexpr uint64_t MAX_PRIME_SIZE = ((1ULL << 60) - 1);

// Server Mod_Switch
constexpr uint64_t LEVELS_FROM_LAST = 0;

// circuit privacy
constexpr uint64_t NOISE_FLOODING_BITS = 368;

Then, after compilation, to run the client and the server either run (in the bin folder, or directly in the docker):

./main # runs the client and the server and outputs the runtimes and noise budgets

or

./client enc # encrypts the input from the client and stores the results on the file system
./server # gets the client inputs from the file system and executes the protocol. Stores the result on the file system
./client dec # gets the server output from the file system and decrypts the result.

Both options perform the benchmarks, output the runtimes and noise budgets and should output "Test passed!" if the protocol produces a correct result.

Acknowledgements

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 825225.

https://safe-deed.eu/

Citing our work

Please use the following BibTeX entry to cite our work in academic papers.

@article{APIR,
  author    = {Alexandros Bampoulidis and
              Alessandro Bruni and
              Lukas Helminger and
              Daniel Kales and
              Christian Rechberger and
              Roman Walch},
  title     = {Privately Connecting Mobility to Infectious Diseases via Applied Cryptography},
  journal   = {CoRR},
  volume    = {abs/2005.02061},
  year      = {2020}
}

[1] https://eprint.iacr.org/2020/522

[2] https://arxiv.org/abs/2005.02061