> For the complete documentation index, see [llms.txt](https://docs.notcentralised.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.notcentralised.com/circuits/hashreceiver.md).

# HashReceiver

The `HashReceiver` circuit is intended for handling and validating the transfer of amounts to a receiver. It creates hashed versions of the amount transferred and the balance of the receiver before and after the transfer.

### Input Signals

The circuit takes the following inputs:

1. **amount**: The amount to be transferred to the receiver.
2. **receiverBalanceBeforeTransfer**: The receiver's balance before the transfer occurs.

```circom
signal input amount;  
signal input receiverBalanceBeforeTransfer;
```

### Output Signals

The circuit outputs the following signals:

1. **receiverBalanceBeforeTransferHash**: The hash of the receiver's balance before the transfer occurs.
2. **receiverBalanceAfterTransferHash**: The hash of the receiver's balance after the transfer has occurred.
3. **amountHash**: The hash of the amount that is transferred.

```circom
signal output receiverBalanceBeforeTransferHash;
signal output receiverBalanceAfterTransferHash;
signal output amountHash;
```

### Components

The circuit utilizes the following components:

* **comp1**: A comparator to ensure that the `amount` is greater than or equal to zero.

```circom
component comp1 = GreaterEqThan(252);
comp1.in[0] <== amount;
comp1.in[1] <== 0;
comp1.out === 1;
```

* **hashAmount**: A `Poseidon` hashing function to create a hash of the `amount`.

```circom
component hashAmount = Poseidon(1);
hashAmount.inputs[0] <== amount;
amountHash <== hashAmount.out;
```

* **hashBeforeBalance**: A `Poseidon` hashing function to create a hash of the receiver's balance before the transfer.

```circom
component hashBeforeBalance = Poseidon(1);
hashBeforeBalance.inputs[0] <== receiverBalanceBeforeTransfer;
receiverBalanceBeforeTransferHash <== hashBeforeBalance.out;
```

* **hashAfterBalance**: A `Poseidon` hashing function to create a hash of the receiver's balance after the transfer.

```circom
component hashAfterBalance = Poseidon(1);
hashAfterBalance.inputs[0] <== receiverBalanceBeforeTransfer + amount;
receiverBalanceAfterTransferHash <== hashAfterBalance.out;
```

### External Circuit Inclusions

The circuit includes `poseidon` and `comparators` circuits from the `circomlib` library.

```circom
include "../../node_modules/circomlib/circuits/poseidon.circom";
include "../../node_modules/circomlib/circuits/comparators.circom";
```

### Main Component

The main component of this circuit file is the `HashReceiver` template.

```circom
component main = HashReceiver();
```

The `HashReceiver` circuit is used primarily for creating hashed versions of the amount being transferred and the receiver's balance before and after the transfer. This can be used for transaction verification and integrity checks within your application.


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