- Status: proposed
- Type: enhancement
- Related components:
protocol - Start Date: 22-March-2017
- Discussion: (fill me in with link to RFC discussion - shepherd will complete this)
- Author: hrobeers
Splitting the coinstake transaction into a monetary creation and a coin-age consumption transaction allows multiple improvements on peercoin's protocol. Apart from aligning the coin creation with Proof-of-Work blocks, it does enable to following changes:
- Multi-signature minting, as described in RFC-0003
- Alignment of the transaction format with bitcoin by moving the coinstake timestamp to the coinbase input (RFC to be created).
- Provides easily manageable limitations on the power of minters to make free transactions.
- The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.
- The verb "TO MINT" or "MINTING" refers to the action of trying to create a Block using Proof-of-Stake. "STAKING" is chosen over "MINTING" to avoid confusion with "MINING".
Multiple community members have been asking about cold minting and the power of minters to add free transactions to their blocks. While all this time, a potential solution for both those problems has been sitting in every Proof-of-Stake block, the unused coinbase transaction. Although the splitting of the coinstake transaction has been described extensively by mquandalle [1], it has never been brought up as a possible alternative for cold minting. This RFC focuses on the discussion about splitting the coinstake transaction, the discussion about multi-signature minting is part of RFC-0003.
Minters are able to include transaction data without paying the fee when they create a block, limited only by the blocksize. As a minter of a small number of blocks might not hold many coin at stake, this can be a method by which a bad actor can drastically bloat the chain without much personal loss. When splitting the coinstake transaction, a natural limit of 1 free KB per minted block will provide minters with flexibility to adjust their outputs as desired while preventing spam.
Proof-of-Stake blocks in the original peercoin protocol carry the coinbase transaction as deadweight.
Only the coinbase vin[0] has been used to carry meta-data (e.g. signaling P2SH support). The diagram below illustrates the original block layout.
Splitting the coinstake transaction into a monetary creation and a coin-age consumption transaction, has the side effect of creating small value outputs. Because those outputs are very unlikely to mint new blocks, node implementations are adviced to join them with a future coin-age consumption transaction.
The minter is awarded a budget of 1 KB for the coin-age consumption transaction in order to adjust their UTXO table as they see fit. If the coin-age consumption transaction is greater than 1 KB, it will have to include the standard fee less 1 KB.
The diagram below illustrates the block layout with a splitted coinstake transaction.
- Paving the road for other improvements like multi-signature minting.
- Limiting the power of minters to spam the blockchain.
- Hard fork
The coin-age consumption transaction could be forced to pay the standard transaction fee, which could be recovered in the monetary creation transaction. As mquandalle [1] describes, the coin-age consumption transaction could then be included by blocks on a competing fork, effectively destroying it's coin-age without providing a block reward. This mechanism would penalize minters building on all forks, and would incentive to mint more actively as orphan blocks risk losing their coin-age.
[1] mquandalle, Split the Peercoin coinstake transaction: https://gist.github.com/mquandalle/7fe702a595f07f4b0f81