Denunciation operation

[sydhds]

Intro

Currently, nothing prevent a user to produce multiple blocks (for the same Slot) or to endorse a block multiple times.
By allowing nodes to produce a new kind of operations: Denunciation; every user will have an incentive of not doing it.
If an invalid Denunciation will just be ignored, a valid Denunciation will slash some locked rolls.
Note that this proposal is to prevent against 'rational' user but cannot do anything against 'pathological' user
that just want to disturb or break the blockclique (at any cost).

Block Denunciation

A "Block Denunciation" is a new kind of "Operation":

• Slot (When what we want to denounce happens)
• PubKey ()
• Proof (So we can verify it really happens)

Proof

The proof will be:

• (Signature1, Hash1)
• (Signature2, Hash2)

Checking that the proof is valid, consists of the following checks:

• Hash1 != Hash2
• Check Signature1 against (Hash1, Slot)
• Check Signature2 against (Hash2, Slot)

Endorsement Denunciation

An "Endorsement Denunciation" is a new kind of "Operation":

• Slot (When what we want to denounce happens)
• Proof (So we can verify it really happens)
• Index (Endorsement index: [0, E-1] where E is the endorsement count (constant))

Proof

The proof will be:

• (Signature1, Hash1)
• (Signature2, Hash2)

Checking that the proof is valid, consists of the following checks:

• Hash1 != Hash2
• Check Signature1 against (Hash1, Slot, Index)
• Check Signature2 against (Hash2, Slot, Index)

Locked rolls (aka Deferred credit)

When a Denunciation is proven valid, we then need to ensure that the user have sufficient funds. If we cannot puncture on node
balance or staked rolls, we will use 'locked' rolls` (or Deferred credit). Selling a roll will lock it for some time (== 4 cycles). Note that it restricts
the time, a denunciation can be produced (A constant value will be defined for this).

When a denunciation is valid (and if balance is not enough), a roll (staked or locked) will be converted back to coins
and then split like:

• 50% will be burned
• 50% will be added to the Block reward (and thus redistributed to the Block creators, Endorsers & Endors'ed)

BlockHeader modifications

For the denunciation proof to be trustable, the BlockHeader signature will be modified like:

• Signature(Hash(serialized header) + slot_serialized)

Endorsement modifications

For the denunciation proof to be trustable, the Endorsement signature will be modified like:

• Signature(Hash(serialized endorsement) + slot_serialized + index)

Bootstrap modifications

Bootstrap needs to be modified to allow to stream some subtracted locked rolls.

[damip]

• Denouncement => Denunciation
• Index for endorsements is from 0 (included) to E-1 (included)
• In the payload, we need to add the public key that created the denounced object
• endorsement proof should contain Index just once (not 3 times)
• stacked => staked

[sydhds]

Done

[sydhds]

As implementation is almost ready and merged into testnet_22. I'm closing this discussion :-)