Add a way to broadcast signatures onchain

[colin-axner]

Problem

There currently exists no way to send confirmation signatures to all nodes without spending the utxo's.

Proposal

This can be implemented in the same way as include-deposit, though I think users should still have the option to spend utxo's without confirm signatures being broadcasted first.

[hamdiallam]

Also requires a design doc/spec before implementing regarding how this fits into the data store.

[wesgraham]

Thoughts on implementation approach below.

Sample Usage:

./plasmacli tx broadcast-sigs
./plasmacli tx broadcast-sigs <input1, input2>
./plasmacli tx broadcast-sigs --confirmSigs0 --confirmSig1

Broadcasting Steps as follows:

1. Retrieve confirm sigs from local storage (iterating over inputs - accessing via clistore)
2. Parse confirm sigs (checking for --confirmSig flag usage overwriting confirm sigs)
3. Create new sigMsg containing confirm Signatures
4. Validate sigMsg
5. Broadcast using cli.BroadcastAndAwaitCommit()

Validate sigMsg includes:
{
plasma.Input1
plasma.Input2
}

Handling Steps as follows:
AnteHandler defines sigMsgHandler

1. Retrieves sigMsgSigner
2. Validates Inputs
   2a) validateConfirmSignatures() already exists
   • Checks signer of confirmhash = signer of sigMsg

Add route for sigMsgHandler

1. Receives validated sigMsg
2. Stores Signature type in DataStore - contains {signature, inputs, signer}

@hamdiallam would appreciate insight on other things needed here

[hamdiallam]

We don't need the signer because we want to allow anyone to broadcast the confirm signature. The ante handler would check that the confirm signature is correctly constructed.

Looks good to me