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Belenios is a verifiable voting system that partly implements the Helios-C protocol described here, which is itself derived from Helios.

It consists of a command-line tool and a web server. Both use the same backend and can be used to organize elections and perform verifications. They employ messages formatted in a common format, a specification of which is available in doc/specification.tex.

Compilation instructions are provided in

Election overview

An election involves several roles: an administrator, a credential authority, trustees and voters. For maximum security, each of these roles must be performed by a different entity. An election can be summarized as follows:

  1. The administrator initiates the process.
  2. The credential authority generates one credential per voter; he sends the private part to each voter and all public parts to the administrator.
  3. Each trustee generates a keypair and sends his/her public key to the administrator.
  4. The administrator collects all public credentials and trustees' public keys and sets up the election.
  5. The administrator opens the election.
  6. Each voter votes; the administrator collects, checks and publishes all the ballots.
  7. The administrator closes the election.
  8. Trustees collectively decrypt the result.
  9. The administrator announces the result of the election.

The command-line tool

Each step can be performed with the help of the command-line tool. The tool is also the most convenient way to exercise the verifiability capabilities of the system.

More information in doc/

The web server

The whole process can be executed using the web server. Each step can be done with a browser. In this case, the formal "administrator" role above is typically shared between the server and a human operator. The server can also assume the roles of credential authority and trustee. Therefore, in its simplest (and weakest) form, an election involves only an operator henceforth called "election administrator" (usually distinct from the person who sets up and administrates the server itself) and voters. In its strongest form, an election involves the election administrator, a credential authority, (at least) two trustees and voters.

More information in doc/


Internal code

By "internal code", we mean everything that is not in the ext/ directory.

Copyright © 2012-2023 Inria, CNRS

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version, with the additional exemption that compiling, linking, and/or using OpenSSL is allowed.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.

External code

Please refer to each file for accurate copyright and licensing information.