> For the complete documentation index, see [llms.txt](https://docs.mazze.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.mazze.io/shielded-space/legacy-pool/transactions.md).

# Pool transactions

{% hint style="warning" %}
This page documents the **legacy Groth16 pool**, superseded by the [shielded space](/shielded-space/privacy.md). See [Legacy pool](/shielded-space/legacy-pool.md).
{% endhint %}

Shielded transfers are encoded as native transactions with a special payload that targets the shielded pool contract.

## Transaction type

* Shielded transactions are represented as `TypedNativeTransaction::Shielded`.
* The payload (`data`) contains the encoded shielded proof and bundle inputs.

## Validation rules

The verifier enforces these constraints for shielded transactions:

* The transaction must be unsigned.
* The action must be `Call` to the shielded pool address.
* `value` must be zero (transfers happen inside the pool).
* `gas_price` must be zero (the proof includes a fee field).
* The payload must not be empty.

The RPC call request builder also enforces recipient, value, and payload checks before building a shielded transaction.

## Sender derivation

Shielded transactions are unsigned. The node derives a synthetic sender address from the transaction hash (`SignedTransaction::new_shielded`).

## Transaction pool behavior

* Shielded transactions are stored in a dedicated `shielded_pool` map (no nonce ordering).
* The packer selects shielded transactions after packing normal native and EVM transactions, respecting remaining gas and block size limits.