ZIP-209: Validate transaction value balances - Implementation

[teor2345]

Motivation

Specifications

Transparent

Transparent inputs to a transaction insert value into a transparent transaction value pool associated with the transaction, and transparent outputs remove value from this pool. As in Bitcoin, the remaining value in the pool is available to miners as a fee.

Consensus rule: The remaining value in the transparent transaction value pool MUST be nonnegative.

https://zips.z.cash/protocol/protocol.pdf#transactions

Sprout

vold takes value from the transparent transaction value pool and vnew adds value to the transparent transaction
value pool . As a result, vold is treated like an output value, whereas vnew is treated like an input value.

As stated in § 4.3 ‘JoinSplit Descriptions’ on p. 36, either vold or vnew MUST be zero.

https://zips.z.cash/protocol/protocol.pdf#joinsplitbalance

Sapling

A positive Sapling balancing value takes value from the Sapling transaction value pool and adds it to the transparent transaction value pool . A negative Sapling balancing value does the reverse. As a result, positive vbalanceSapling is treated like an input to the transparent transaction value pool , whereas negative vbalanceSapling is treated like an output from that pool.

https://zips.z.cash/protocol/protocol.pdf#saplingbalance

Orchard

vbalanceOrchard is encoded in a transaction as the field valueBalanceOrchard. If a transaction has no Action descriptions, vbalanceOrchard is implicitly zero. Transaction fields are described in § 7.1 ‘Transaction Encoding and Consensus’ on p. 116.

A positive Orchard balancing value takes value from the Orchard transaction value pool and adds it to the transparent transaction value pool . A negative Orchard balancing value does the reverse. As a result, positive vbalanceOrchard is treated like an input to the transparent transaction value pool , whereas negative vbalanceOrchard is treated like an output from that pool.

https://zips.z.cash/protocol/protocol.pdf#orchardbalance

Designs

Solution

Alternatives

Related Work