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

# Reusing arguments

This document explains how to reuse encrypted arguments in applications where the same arguments are used repeatedly.

Encrypting data can be resource-intensive, especially when the same argument or set of arguments is used multiple times. In such cases, it’s inefficient to encrypt and transfer the arguments repeatedly. Instead, you can encrypt the arguments separately and reuse them as needed. By encrypting the arguments once and reusing them, you can optimize performance by reducing encryption time, memory usage, and network bandwidth.

Here is an example:

```python
from concrete import fhe

@fhe.compiler({"x": "encrypted", "y": "encrypted"})
def add(x, y):
    return x + y

inputset = [(2, 3), (0, 0), (1, 6), (7, 7), (7, 1), (3, 2), (6, 1), (1, 7), (4, 5), (5, 4)]
circuit = add.compile(inputset)

sample_y = 4
_, encrypted_y = circuit.encrypt(None, sample_y)

for sample_x in range(3, 6):
    encrypted_x, _ = circuit.encrypt(sample_x, None)

    encrypted_result = circuit.run(encrypted_x, encrypted_y)
    result = circuit.decrypt(encrypted_result)

    assert result == sample_x + sample_y
```

Note when you use `encrypt` method:

* If you have multiple arguments, the `encrypt` method would return a `tuple`.
* If you specify `None` as one of the arguments, `None` is placed at the same location in the resulting `tuple`.
  * For example, `circuit.encrypt(a, None, b, c, None)` returns `(encrypted_a, None, encrypted_b, encrypted_c, None)`.
* Each value returned by `encrypt` can be stored and reused anytime.

{% hint style="warning" %}
The order of arguments must be consistent when encrypting and using them. Encrypting an `x` and using it as a `y` could result in undefined behavior.
{% endhint %}


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