Plexi

Plexi is a flexible auditor for Key Transparency systems.

Tables of Content

• Features
• Installation
• Usage
  • Configure your auditor remote
  • List monitored Logs
  • Audit a signature
• Conduct
• License

Features

• Verify authenticity of a signature, to confirm it has been signed by a given public key
• Verify the validity of facebook/akd proofs
• List Logs an Auditor monitors

Installation

Environment	CLI Command
Cargo (Rust 1.81+)	cargo install plexi

Usage

Use the --help option for more details about the commands and their options.

plexi [OPTIONS] <COMMAND>

Configure your auditor remote

plexi does not come with a default remote auditor, and you will need to choose your own.

You can do so either by passing --remote-url=<REMOTE> or setting the PLEXI_REMOTE_URL environment variable.

A common remote is provided below:

Name	Remote
Cloudflare	https://plexi.key-transparency.cloudflare.com

If you have deployed your own auditor, you can add a remote by filing a GitHub issue.

List monitored Logs

An auditor monitors multiple Logs at once. To discover which Logs an auditor is monitoring, run the following:

plexi ls --remote-url 'https://plexi.key-transparency.cloudflare.com'
whatsapp.key-transparency.v1

Audit a signature

The Key Transparency Auditor vouches for Log validity by ensuring epoch uniqueness. and verifying the associated proof

plexi audit provides information about a given epoch and its validity. It can perform a local audit to confirm the auditor behaviour.

For instance, to verify WhatsApp Log auditted by Cloudflare Auditor, run the following:

> plexi audit --remote-url 'https://plexi.key-transparency.cloudflare.com' --namespace 'whatsapp.key-transparency.v1' --long
Namespace
  Name                	: whatsapp.key-transparency.v1
  Ciphersuite         	: ed25519(protobuf)

Signature (2024-09-23T16:53:45Z)
  Epoch height      	: 489193
  Epoch digest      	: cbe5097ae832a3ae51ad866104ffd4aa1f7479e873fd18df9cb96a02fc91ebfe
  Signature         	: fe94973e19da826487b637c019d3ce52f0c08093ada00b4fe6563e2f8117b4345121342bc33aae249be47979dfe704478e2c18aed86e674df9f934b718949c08
  Signature verification: success
  Proof verification	: success

If you already know the auditor verifying key, you can pass it via --verifying-key. Plexi will verify that the key is advertised by the auditor, and that the signature is valid against it.

plexi audit \
  --remote-url 'https://plexi.key-transparency.cloudflare.com' \
  --namespace 'whatsapp.key-transparency.v1' \
  --verifying-key '2bbfbb39997fdb95feee40ef9f8827de0256732be06f64ed6408cc7e97c7f4d4'

Conduct

Plexi and Cloudflare OpenSource generally follows the Contributor Covenant Code of Conduct. Violating the CoC could result in a warning or a ban to Plexi or any and all repositories in the Cloudflare organization.

License

This project is Licensed under Apache License, Version 2.0.