# JoinSplits

Veilnyx protocol transactions are specifically based on JoinSplit [transactions from ZCash](https://forum.zcashcommunity.com/t/is-my-understanding-of-how-zcash-works-correct/961).  In the overview, in a JoinSplit, a number of existing notes are spent, and new notes are created such that the total value remains conserved.

When a user spends his notes in a transaction, the so-called **nullifiers** of those notes need to be revealed. A nullifier is a unique element that is cryptographically bound to a note and can only be calculated with the knowledge of a note's properties, i.e. by its owner. The spent notes' nullifiers are marked in the application to prevent notes with already marked nullifiers from being spent again. A fresh set of new notes is created such that the total value is conserved in the state of application. The bearer of the newly created notes, however, may change in a transaction. In case of an external deposit/withdrawal of some value, the equivalent value is added/subtracted from newly created notes. Only the **commitments** of newly created notes are publicly shown during the transaction and are inserted into a Merkle tree data structure holding commitments of all notes ever created.

<figure><img src="/files/PNiKOikIYCmFls9e7EaV" alt="" width="563"><figcaption><p>JoinSplit</p></figcaption></figure>

The figure above represents notes involved in a JoinSplit. These transactions can be broadly divided into three types.&#x20;

* **Deposit:** Deposit transaction where a non-zero external amount $$V\_{in}$$ sent with the transaction payload, and equally valued one or more notes ($$N\_3$$ and $$N\_4$$) are created. Any spent notes’ ($$N\_1$$ and $$N\_2$$) value or any external withdrawal amount $$V\_{out}$$ are zero.
* **Withdraw:** Withdraw transaction where non-zero value notes ($$N\_1$$ and $$N\_2$$)  are spent to withdraw some non-zero value  $$V\_{out}$$ less than or equal to the sum of values of spent notes. Any change value left is accounted for by the creation of one or more notes ($$N\_3$$ and $$N\_4$$)  for the user.
* **Transfer:** Transfer transaction where no external value is revealed (i.e. $$V\_{in}$$ = $$V\_{out}$$ = 0). Some notes ($$N\_1$$ and $$N\_2$$) are spent to create some new notes ($$N\_3$$ and $$N\_4$$) such that values remain conserved. However, the bearer of some note ($$N\_3$$ in the figure) may change, which in effect represents a fully private peer-to-peer transfer of value.


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