SCAPI is an open-source general library tailored for Secure Computation implementations. SCAPI provides a flexible and efficient infrastructure for the implementation of secure computation protocols, that is both easy to use and robust. We hope that SCAPI will help to promote the goal of making secure computation practical.

Why Should I Use SCAPI?

  • SCAPI provides uniformity. As of today, different research groups are using different implementions. It is hard to compare different results, and implementations carried out by one group cannot be used by others. SCAPI is trying to solve this problem by offering a modular codebase to be used as the standard library for Secure Computation.
  • SCAPI is flexible. SCAPI’s lower-level primitives inherit from modular interfaces, so that primitives can be replaced easily. SCAPI leaves the choice of which concrete primitives to actually use to the high-level application calling the protocol. This flexibility can be used to find the most efficient primitives for each specific problem.
  • SCAPI is efficient. Most of SCAPI’s low level code is built upon native C/C++ libraries using JNI (the java native interface) in order to run more efficiently. For example, elliptic curve operations in SCAPI are implemented using the extremely efficient Miracl library written in C.
  • SCAPI is built to please. SCAPI has been written with the understanding that others will be using it, and so an emphasis has been placed on clean design and coding, documentation, and so on.


SCAPI is composed of the following three layers:

  1. Low-level primitives: these are functions that are basic building blocks for cryptographic constructions (e.g., pseudorandom functions, pseudorandom generators, discrete logarithm groups, and hash functions belong to this layer).
  2. Non-interactive mid-level protocols: these are non-interactive functions that can be applications within themselves in addition to being tools (e.g., encryption and signature schemes belong to this layer).
  3. Interactive mid-level protocols: these are interactive protocols involving two or more parties; typically, the protocols in this layer are popular building blocks like commitments, zero knowledge and oblivious transfer.

In addition to these three main layers, there is an orthogonal communication layer that is used for setting up communication channels and sending messages.

SCAPI Architecture