Command Line Interface

A single command line utility pvss is provided to serve as an example on how to use the API.

Generic usage is pvss <datadir> <command> [ARGS...] where datadir is some directory which contains all public messages from the PVSS workflow.

Help for the available commands is included in the tool: pvss --help

Example

The following sequence of shell commands is executed by six different users who share a data directory. E.g. use git to synchronize it between the users. All files inside datadir are public. All files outside of it are private.

(init)     $ pvss datadir genparams rst255
(alice)    $ pvss datadir genuser Alice alice.key
(boris)    $ pvss datadir genuser Boris boris.key
(chris)    $ pvss datadir genuser Chris chris.key
(dealer)   $ pvss datadir splitsecret 2 secret0.der
(receiver) $ pvss datadir genreceiver recv.key
(boris)    $ pvss datadir reencrypt boris.key
(alice)    $ pvss datadir reencrypt alice.key
(receiver) $ pvss datadir reconstruct recv.key secret1.der

secret0.der and secret1.der should compare equal. The dealer and receiver can encrypt an actual payload by using that file as a shared key.

Directory Structure

The datadir is made up of:

• parameters - Cryptographic group and other parameters (SystemParameters).

• users - Directory with random file names for each user public key (PublicKey).

• shares - Shares of the secret (SharedSecret).

• receiver - Receiver’s public key (PublicKey).

• reencrypted - Directory with random file names for re-encrypted shares (ReencryptedShare).