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Mimblewimble Privacy Transaction

This article describes specific aspects of how Mimblewimble might be incoperated in Neatcoin.

Status#

Things on this page has not yet been implemented.

Crypto library#

The project does not aim at writing any base-level crypto libraries. We use whatever is available at hands. This means:

  • Curve25519 for all Mimblewimble transaction handlings.
  • Bls12_381 for proof-of-stake pairing operations.

Readers may notice that we do not use the same crypto as in Grin (which uses secp256k1). Thanks to the dalek and schnorrkel project in Rust, curve25519 has already got sufficient support for running operations needed for Mimblewimble.

Mimblewimble#

The transaction format and all mimblewimble operations will mostly resemble what looks like in Grin.

Proof-of-stake#

The Coinbase output and kernel feature is removed. In replacement, we introduce two new features Stake and Reward.

All proof-of-stake data structures live in a place outside of Mimblewimble. We can think of them as a validator set with a BLS public key and current rewards.

Both the Stake and Reward kernel feature will have a reference to a BLS public key.

If an output contains the Stake feature, it initiates an intention to validate. It reveals the staker's BLS public key, but does not reveal the amount. In addition to the normal rangeproof to make sure the amount is a non-negative value, an additional rangeproof is carried out to make sure the amount is greater than 64 NEAT. Otherwise, the block is considered invalid.

All Stake outputs are immediately forbidden to be used as inputs. At the end of the block, their validator keys are added to the proof-of-stake validator set. We use the same strategy as in eth2 to give all validators the same voting rights.

From this point on, the proof-of-stake functions exactly the same as Eth2's beacon chain proof-of-stake specifications.

The proof-of-stake algorithm will accumate rewards. Upon reaching a threshold, validators can send Reward inputs on the Mimblewimble side to mint those coins to be usable.

The proof-of-stake side has specific transactions for sending attestations and handling slashing reportings. Those transactions are not in any way related to Mimblewimble transactions.

Either voluntarily or forced, a validator can exit staking. In this case, the validator set state maintains the data until the exit period. After that, Stake-featured outputs are re-allowed to be used as other transaction's inputs.

Slashing#

A validator can be slashed if it malfunctions. In this case, rewards can go negative. The Stake-featured outputs will continue to be forbidden to be used even when the validator exits.