go-yosovss: Go implementation of YOSO-style verifiable secret sharing

IMPORTANT DISCLAIMER: This code is just a proof of concept. It is not meant to be production code and has never been audited. It is provided as is. We make absolutely no guarantees or warranties to its correctness, safety, and reliability. In particular, we make absolutely no security guarantees or warranties in regard to any changes/additions to libsodium.

This repository contains a proof-of-concept implementation in Go of the YOSO-style verifiable secret-sharing protocol from the article:

"Threshold Cryptography as a Service (in the Multiserver and YOSO Models)", Fabrice Benhamouda, Shai Halevi, Hugo Krawczyk, Alex Miao, and Tal Rabin ACM-CCS 2022.

The protocol that it implemented here corresponds to an older version of this article than what's in the ACM-CCS proceedings. This old version can be retrieved from this link, it is provided only for the purpose of documenting the code. Implemented here is (a very small variant of) the protocol as described in Section 4.3.3 in this file.

Getting Started

Requirements

• Ubuntu 20.04 (or later) or macOS 11 (or later)
• If on macOS, HomeBrew is recommended
• go version at least 1.15 - tested with 1.17.6
  • on Ubuntu: https://golang.org/doc/install
  • on macOS: brew install go
• libsodium 1.0.18
  • on Ubuntu: sudo apt install libsodium-dev
  • on macOS: brew install libsodium
• swig
  • Used in primitives/vss to interface with NTL
  • on Ubuntu: sudo apt install swig
  • on macOS: brew install swig
• ntl:
  • on Ubuntu: sudo apt install m4 libgmp-dev libntl-dev
  • on macOS: brew install ntl

Running the project

Run:

make test

Benchmarking

Micro-benchmarks of elliptic curve operations

cd primitives/curve25519
go test -bench .

Benchmark of the resharing protocol

See the README for the protocol.

Organization

• communication: communication layer, broadcast channel. Currently this is "fake" using Go channels, there is no actual networking implemented. But it can easily be added.
• msgpack: functions helping for serializing via msgpack
• primitives: cryptographic primitives used by the protocol.
• protocols/resharing: the resharing protocol. See README.md inside

Contribute

Requirements

• golangci-lint
  • on Ubuntu: https://golangci-lint.run/usage/install/#local-installation (note that you must have a single folder in your $GOPATH if you run the proposed command)
  • on macOS: brew install golangci-lint
• gosec
  • on Ubuntu: https://github.com/securego/gosec#local-installation
  • on macOS: brew install gosec
• genny: go get github.com/cheekybits/genny:
  • Used to generate files gen-* except gen-codecgen.go
  • Note that we commit those files too in case genny becomes unavailable
• codecgen: go get -u github.com/ugorji/go/codec/codecgen:
  • Used to improve performance of go-codec
  • Do not forget to update protocol/resharing/auditor/codecgen.go if adding new structures that need to be encoded

Lint code

Run:

make lint

If you have error, you can try to automatically fix them:

make lint-fix

If using Goland or Visual Studio Code, it is recommended to use the Golangci integration: https://golangci-lint.run/usage/integrations/

Fixing common issues

Msgpack decode some struct field into nil

Re-generate the codec file:

make generate

Huge memory use

If using pprof shows nothing, the issue is most likely in the C library (missing free from a malloc).

Fixing common gosec issues

G107: Url provided to HTTP request as taint input

Verify there is no security risk and ignore using // #nosec G107.

G304: File path provided as taint input

Verify there is no security risk and ignore using // #nosec G304.

G307: Deferring a method which returns an error

When reading a file

// #nosec G307
// no need to check error on close when reading file
defer inFile.Close()

When writing a file

Always close the file manually at the end of the function:

outFile, err := os.Create(fileName)
if err != nil {
    return _, fmt.Errorf("error opening file '%s': %v", fileName, err)
}

// #nosec G307
// manually closing on success, so no need to check error again
defer outFile.Close()

// ...

if err := outFile.Close(); err != nil {
    return _, fmt.Errorf("error closing file '%s': %v", fileName, err)
}

Advanced Topics

Test Locally Github Actions

This is only if you are changing Github actions.

Use https://github.com/nektos/act

act

Note the file .actrc that make us use manually the real image instead of the default one. There are 2 reasons: nektos/act#269 and the fact that gcc is not included in the default image (and is needed by cgo) See https://github.com/nektos/act#configuration