This is a high-performance implementation of private information retrieval (PIR) based on distributed point functions (DPF). As this is a multi-server (more specifically a 2-server) PIR, we need two non-colluding servers with identical databases. For our use case, where this DPF-PIR is being used in a Certificate Transparency (CT) log server, we specialize on databases of SHA-256 hash values, which are stored in a hashdatastore object. This aligns nicely with the use of AVX/AVX2 instructions to speed up calculations. We also make use of AES-NI instructions to create a high-performance PRF.
Example execution of microbenchmarks for a tree with 2^22 elements.
mkdir build && cd build
cmake .. -DCMAKE_BUILD_TYPE=Release
make
./dpf_pir 22
Some parts like the AES-NI implementation are taken from Peter Rindal's public domain CryptoTools.
Paper: Daniel Kales, Olamide Omolola, Sebastian Ramacher. Revisting User Privacy for Certificate Transparency. EuroS&P 2019