Demo for Signature generation: Coordinator CLI

[mpguerra]

Motivation

We want to simulate a simple execution of FROST to show potential FROST implementers how to use the FROST library.

Scope

Build a simple CLI to demo signature aggregation by a coordinator in a 2-round FROST signature generation protocol, given a number of key shares and commitments from signature participants.

All other actions that the coordinator entity would perform, prior to signature aggregation, during the FROST signature generation can be done by the person running the FROST demo, e.g by entering in the relevant details when prompted by the participant CLI instances in ZcashFoundation/frost#239.

Specification

Round 2: Signature Aggregation

To perform signature aggregation, the CLI will prompt for the following data to be entered:

• The list of signature shares, sig_shares, for each participant in the signature generation.
• The message, msg, to be signed
• The list of commitments, commitment_list.

The CLI will first validate each signature share, sig_share_i, by running DeserializeScalar.

If all signature shares are valid, the Coordinator CLI can proceed to aggregate them and produce the final signature by running, aggregate, with the previously entered data (sig_shares, msg and commitment_list) to generate the final Schnorr signature, (R,z) and output this to the terminal.

[mpguerra]

Hey team! Please add your planning poker estimate with Zenhub @conradoplg @dconnolly @natalieesk