Duality Labs OpenFHE Experiments for Encrypted Network Measurement/Control and Secure Data Distribution with Proxy Re-Encryption

July 2024: full release 3.1 version - bug fixes for PRE, works with OpenFHE 1.2.0

This repository contains multiple examples of Fully Homomorphic Encryption (FHE) for Proxy Re Encryption and Threshold-FHE encrypted network control functions developed under DARPA funding for the I2O Open, Programmable, Secure 5G (OPS5G) program. Note the utility of these examples are valid for many forms of wireless and wireline networks, not just 5G networks.

Questions should be forwarded to the Duality Principal Investigator, Dr. David Bruce Cousins, email: [email protected]

Synopsis

This repository contains several sample programs for encrypted data processing between cooperating network processes with the goals of:

• Distributing sensitive data throughout a network in a secure manner

• Performing distributed network measurement and control functions using Threshold FHE to increase the work effort required to subvert the system via side-channel attacks etc.

There are several example programs available that show how to use the OpenFHE open-source library to build systems of multiple cooperating heavyweight processes, using the Google RPC system both in a client-server and peer-to-peer framework.

We show the capabilities of OpenFHE's Proxy-Re-encryption (allowing a third party to re-encrypt Alice's encrypted data with Bob's decryption key without involving Alice). We also show the use of OpenFHE's Threshold Encryption (where multiple parties cooperate on a common computation task and all participate in decryption).

Note 1 several of these examples are first prototypes, and may not represent the best way to distribute the responsibility of Crypto context generation, and key distribution. As we develop better examples, we may revise or delete earlier ones. Earlier examples will always be available in prior repository releases.

Note 2 the distribution contains a large number of unit tests for the underlying communications frameworks in the tests directory. For information on these tests (how to add tests, run tests, etc.) visit the README.md file in the tests sub-directory.

Note 3 Earlier releases had Some examples using the RAVEN network simulation framework to emulate a multiple domain network. This system is not well supported, and was difficult to maintain, so we removed support for it this release.

Acknowledgments and Distribution

Distribution Statement ‘A’ (Approved for Public Release, Distribution Unlimited). This work is supported in part by DARPA. The views, opinions, and/or findings expressed are those of the author(s) and should not be interpreted as representing the official views or policies of the Department of Defense or the U.S. Government.

This work is supported by DARPA through contract number HR001120C0157. This work was conducted by Duality Technologies as a subcontractor to University of Southern California / Information Sciences Institute.

Note previous DARPA approved releases of some source code examples contained herin were done under the title "PALISADE Serialization examples". PALISADE versions have been ported to OpenFHE and can be found at the OpenFHE Serial Examples repository. That repository contains basic examples of threshold and proxy re-encryption use cases between multiple parties using basic Inter-process communication (IPC) based on file/mutex and TCP/IP sockets.

The Example Systems

A short description of the various examples systems now follows. All systems are to be found in the src sub-directory of the root directory.

Multi-Hop, Muli-Trust Zone PRE Network For AES Key Distribution Demo using Client-Server based GRPC

Found in the src/pre_grpc_demo directory. This example demonstrates an application to distribute sensitive data such as symmetric keys from producers to consumers through multiple brokers across multiple trust zones. A single trusted server in the first trust zone generates OpenFHE Crypto Contexts for servers in other trust zones, brokers, producers and consumers. The producers and consumers generate their own public key, secret key pairs. The server generates the key pair for each broker in its trust zone and re-encryption keys from upstream broker to downstream broker or consumer. A cipher-text generated by the producer is relayed through the brokers to the consumer. It also includes an example of denying access to unauthorized consumers. Note that the brokers can perform a re-encryption but cannot decrypt.

The PRE Network example is built with the google RPC framework. Please note one has to install gRPC and Google Protobufs before this can be compiled (see section below). Some detailed information on how gRPC is used for client/server examples can be found in the file src/pre_grpc_demo/Grpc_files_explained.md

GRPC also allows authenticated connections between the clients and server using ssl. This is done by generating certificates for the servers and clients using the scripts in scripts/authentication. The folder in which the certificate files are generated (usually the build folder) is passed as a command line argument to the server and the client targets to establish a secure channel for communication. Refer to "Certificate setup for gRPC communications" section below under "Building Instructions".

A single thread test bench program pre is used to test parameter settings. A Python script scripts/multihop_params.py and associated support files provide the means to determine the appropriate crypto parameters to use for a given configuration. Instructions for running a multi-hop example are provided below. An additional script multi_pre_test_singlethread.sh in the benchmarks folder can be used to run the target benchmarks/pre_d.cpp (needs to be moved to pre_grpc_demo/targets to be built) multiple times in order to conduct decryption failure rate experiments.

Peer-to-Peer Network Communication Framework

Found in src/peer_to_peer_framework that defines the communication framework (based on GRPC) to send and receive messages between multiple nodes without an intermediate server. The code defines a node object. The nodes are initialized as a GRPC server that can receive messages from other node servers, with internal message queuing and broadcast. To send a message to another node, the local node creates an internal client instance and sends the message. There is simple handshaking to detect failed nodes. There are no examples within this directory. Rather, all peer-to-peer examples use this code.

The following files define the different functionalities of the Node object.

1. node.h : the node implementation class and the functions that are invoked in the applications to register a node, create message queues and send and get messages

2. node_internal_client.h : create a client instance within the node server to send messages to other node servers.

3. node_request.h: The node server side processing of the messages received from other nodes and assigning it to the correct message queues.

4. node_server_async_base.h : gRPC object for the node server to handle async requests

5. comm_utils(.h,.cpp) : utilities for creating the message structure, message queue objects and processing command line arguments.

Threshhold FHE with Abort Recovery Examples

There are a few different versions of this example:

• src/threshold_fhe_aborts contains single file implementations used for benchmarking the core crypto operations without any socket communications. The file threshold_fhe.cpp runs without testing aborts, and threshold_fhe_aborts.cpp tests the abort recovery system.

• src/threshnet_aborts_grpc_demo is a client-server version.

• src/threshnet_aborts_p2p_demo is a peer-to-peer version.

Both client-server and peer-to-peer use GRPC for secure socket communications, but are coded in a completely different manner.

All these examples implement multiparty a threshold FHE computation service using gRPC. Demo scripts to run a threshold example with 5 parties in both client-server and peer-to-peer settings are in the demos folder (see below). Additional files for running the examples with 3 and 7 parties can be found in the benchmarks folder.

Network Adjacent Co-Measurement Client-Server Examples

Found in the src\threshnet_adjacent_measure_demo directory, this example demonstrated two nodes comparing the data from a common measurement via a controller that randomizes the ciphertexts from both nodes. The only information extracted is whether the measurements are the same or not.

Note a peer-to-peer example of this can be found in the src/network_measure_examples as network_measure and network_measure_with_controller for versions with and without a controller.

Network Measurement Examples (are built using the peer to peer framework for GRPC communication)

Found in src/network_measure_examples. The two examples include

1. an adjacent network measure, where two nodes take measurements of a shared integer value (such as the bandwidth between them) and determine if the measurement is the same or different in a secure manner. There are configurations with and without a third party controller node.

2. Measurement of values along a path. This example accumulates values in a vector from each node in a path, and computes some operations on the accumulated data. This is done using threshold FHE.

The current path measurement example allows for computation of some statistics (such as mean, squares of mean and cubes of mean as of now) by accumulating encrypted data along a path of nodes. A trusted controller receives the partial decryption shares and does the computation. The same ciphertext is used to accumulate data from multiple nodes (treated as a register). The following files are specific to the path measurement example

1. register_functions.h : functions used for accumulation of data into the ciphertext.

2. path_measure_crypto_functions.h, .cpp : The cryptographic functions such as joint public key, evaluation keys generation along a path.

Building Instructions

Here are instructions for building each of the examples.

Building Examples with gRPC

Several examples use gRPC as their interprocess communications system. They require gRPC and Google protobufs to be installed on your system. Based on suggestions from Google's documentation, we recommend installing gRPC locally if it is not pre-installed in your system.

Detailed instructions for this can be found in the file Installing_gRPC.md located in the root directory. Please refer to those and isntall gRPC on your system before proceeding to the remainder of the build instrutions below.

Build instructions for Ubuntu

Please note that we have not tried installing and running these examples on windows or macOS. If anyone does try this, please update this file with instructions and generate a merge request. It's recommended to use at least Ubuntu 19 gnu g++ 7 or greater.

1. Install prerequisites (if not already installed): g++, cmake, make, boost and autoconf. Sample commands using apt-get are listed below. It is possible that these are already installed on your system.

   sudo apt-get install build-essential #this already includes g++

   sudo apt-get install autoconf

   sudo apt-get install make

   sudo apt-get install cmake

   sudo apt-get install libboost-all-dev

   Note that sudo apt-get install g++-<version> can be used to install a specific version of the compiler. You can use g++ --version to check the version of g++ that is the current system default. The version of boost installation required might be 1.71 or higher for compatibility.

2. Install OpenFHE on your system. The examples codes here require using the v1.2.0 tag of the OpenFHE development repository to be found here.

   Full instructions for installing OpenFHE are to be found in the README.md file in the OpenFHE repo.

   Run make install at the end to install the system to the default location (you can change this location, but then you will have to change the CMakefile in this repo to reflect the new location).

   Note you may have to execute the following on your system to automatically find the installed libraries and include files:

   sudo ldconfig

3. Clone this repo onto your system.

4. Create the build directory

   mkdir build

5. Move to that directory and run cmake.

   cd build

   If you have not added them to your $PATH environement variable, specify the directories where you have installed gRPC an Protobufs to the cmake command. For example if I installed it in /home/thisuser/opt/grpc then you need to run this as:

cmake -DProtobuf_DIR=/home/thisuser/opt/grpc/lib/cmake/protobuf -DgRPC_DIR=/home/thisuser/opt/grpc/lib/cmake/grpc ..

Note if you used a different install directory for OpenFHE (for
example if I installed it in `/home/thisuser/opt/openfhe64_1_2_0` then I would need to
run this as 

> `cmake -DOPENFHE_INSTALL_DIR=/home/thisuser/opt/openfhe64_1_2_0/ -DProtobuf_DIR=/home/thisuser/opt/grpc/lib/cmake/protobuf -DgRPC_DIR=/home/palisade/opt/grpc/lib/cmake/grpc ..`

Note: If you have multiple versions (revisions) of OpenFHE on
your system, `cmake` may find the wrong one and cause build errors
(`cmake` uses an elaborate set of search rules to find a library,
and it may not be the version you expect). If you have strange
build errors, consider using the above `-DOPENFHE_INSTALL_DIR` to
point specifically to the correct version. Refer to the main `CMakeLists.txt` for more details. 

1. Build the examples using make. Please note that OpenFHE serialization uses the CEREAL system for crypto object serialization which can result in some long compile times.

   make

   Executables for all the examples will be in the build/bin directory. If you have a multicore system make -j will speed up the build process.

Certificate setup for GRPC communications

GRPC allows to enable communications with ssl if needed. When ssl is enabled, the nodes use certificates to authenticate each other. A test certificate setup is provided for the examples using the scripts in authentication folder. Each example built with GRPC has a folder in the authentication folder and lists the nodes needed for the example in the nodes file.

To generate certificates, run the following command from the build directory:

sh ../scripts/authentication/create_root_cert.sh

sh ../scripts/authentication/create_nodes_cert.sh <example_directory_name>

For example, to run the adjacent measure example without controller, run

sh ../scripts/authentication/create_nodes_cert.sh adjacent_network_measure

Please make sure that the node names listed in the nodes file is the same as the process name when a GRPC process is triggered in command line with the -n flag. Remove the node folders, *.crt and *.key files in the build directory after running each example to be sure there is no overlap of nodes between examples.

Please look at the scripts/authentication directory to determine the appropriate directory names to use.

If you are going to generate all the demo scripts then you can run the file

sh ../scripts/authentication/create_all_demo_certs.sh

Several Examples are available for each feature. Please see the file Running_Examples.md for complete detailed instructions.

Note some classes of examples are still currently being worked on. If a class has been completed, it will be marked Verified in the tile.