[Protocol Study #4] Transactions Unpacked: JoinSplit to Actions

​We now have the note primitives: a commitment goes into a tree, a nullifier is revealed on spend, a zk-SNARK proves the link. Session 4 threads them into the thing that actually moves value, the transaction, and follows how the shape of a shielded transfer changed across three eras of Zcash.

​The whole session hangs on one question asked three times: how does a transfer prove it created exactly as much value as it destroyed?

• ​Sprout answers it inside one bundled JoinSplit.

• ​Sapling splits the transfer apart and answers across the whole transaction.

• ​Orchard re-merges it into a single Action.

​Reading: Spec §3.4 to §3.7
Where: https://discord.gg/zcash (Zcash Global Discord Stage)

​Recorded and translated by Zcash Brazil